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JHUAPL Interstellar probe study (2019)
by
AegeanBlue
on 21 Nov, 2018 21:36
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I did not find a relevant thread so I am starting one here. I think it belongs more here than at Advanced Concepts, because the study tries no to be one. As part of the studies for the next Heliophysics Decadal Survey JHUAPL is studying a probe to get to 1,000 AU within 50 years. I became aware of the effort through a FISO telecon, which slides I have attached. The probe will weight 300-800 kg of which 40 kg will be instruments. By comparison New Horizons is a 478 kg with 30.4 kg of instruments, Parker Solar Probe 685 kg with 50 kg of instruments, while Pioneer 10/11 and Ulysses were lighter. The current mission plan is for an SLS launch to Jupiter, reverse gravity assist to reduce speed, plunge into the Sun at 4 solar radii (Parker Solar Probe will reach 8 solar radii) and use an Oberth maneuver to achieve 8 AU per year or twice the heliospheric escape speed of Voyager 1. Since they will be in the area, they are also proposing that a Kuiper Belt target is also target for a fast flyby.
For the Oberth maneuver this requires a solid stage with at least twice the power of STAR 48. Now there are first stage solid boosters out there much stronger than the STAR 48, but whether they can survive several years of the cold in space and the heat at 4 solar radii, I do not know. The FISO telecon mentions that there will be a follow up at a session at the Fall AGU and a final report will be submitted to the NASA director in February 2019 to decide if to proceed to Phase II.
AGU already has its sessions up. One relevant session is SH33C: The Interstellar Probe Mission: Study Findings and Next Steps Posters, available at
https://agu.confex.com/agu/fm18/prelim.cgi/Session/48708There is also session SH029, which has its abstracts up here:
https://fallmeeting.agu.org/2018/pio-abstract-search/?proposed_session_abbreviation=SH029&l=%252F2018%252Fpio-abstract-search%252F&abstract_search=1&simian_search=1&abstract_search_paged=1I am hoping that someone takes notes about what is told at that session and gives us the gist. Also it would be nice if anyone has more information to share about the project. I remember Voyager scientists mentioning how Heliophysics proposes such a mission on a regular basis but it gets shot down due to technological immaturity. From what I can tell, after the recent launch of Parker Solar Probe and the upcoming launch of ESA's Solar Orbiter to which NASA is contributing instruments, NASA heliophysics no longer has a flagship mission.
Please do NOT start discussing the merits of various launchers. This is a circa 2030 launch date mission, and we have had this discussion here ad nauseam.
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#1
by
Hobbes-22
on 22 Nov, 2018 14:17
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#2
by
Eric Hedman
on 22 Nov, 2018 20:07
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It looks like we are in no danger of running out of creative ideas for exploring space. THat's one reason I find it so fascinating. Even though many of us won't be around if and when this gets out to 1,000 AU, this idea is worth looking into. The coming generations of space enthusiasts will have even more new discovers to witness.
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#3
by
RotoSequence
on 22 Nov, 2018 20:22
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Seems like a good opportunity for an Oumuamua flyby, too.
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#4
by
russianhalo117
on 22 Nov, 2018 23:39
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I did not find a relevant thread so I am starting one here. I think it belongs more here than at Advanced Concepts, because the study tries no to be one. As part of the studies for the next Heliophysics Decadal Survey JHUAPL is studying a probe to get to 1,000 AU within 50 years. I became aware of the effort through a FISO telecon, which slides I have attached. The probe will weight 300-800 kg of which 40 kg will be instruments. By comparison New Horizons is a 478 kg with 30.4 kg of instruments, Parker Solar Probe 685 kg with 50 kg of instruments, while Pioneer 10/11 and Ulysses were lighter. The current mission plan is for an SLS launch to Jupiter, reverse gravity assist to reduce speed, plunge into the Sun at 4 solar radii (Parker Solar Probe will reach 8 solar radii) and use an Oberth maneuver to achieve 8 AU per year or twice the heliospheric escape speed of Voyager 1. Since they will be in the area, they are also proposing that a Kuiper Belt target is also target for a fast flyby.
For the Oberth maneuver this requires a solid stage with at least twice the power of STAR 48. Now there are first stage solid boosters out there much stronger than the STAR 48, but whether they can survive several years of the cold in space and the heat at 4 solar radii, I do not know. The FISO telecon mentions that there will be a follow up at a session at the Fall AGU and a final report will be submitted to the NASA director in February 2019 to decide if to proceed to Phase II.
AGU already has its sessions up. One relevant session is SH33C: The Interstellar Probe Mission: Study Findings and Next Steps Posters, available at https://agu.confex.com/agu/fm18/prelim.cgi/Session/48708
There is also session SH029, which has its abstracts up here: https://fallmeeting.agu.org/2018/pio-abstract-search/?proposed_session_abbreviation=SH029&l=%252F2018%252Fpio-abstract-search%252F&abstract_search=1&simian_search=1&abstract_search_paged=1
I am hoping that someone takes notes about what is told at that session and gives us the gist. Also it would be nice if anyone has more information to share about the project. I remember Voyager scientists mentioning how Heliophysics proposes such a mission on a regular basis but it gets shot down due to technological immaturity. From what I can tell, after the recent launch of Parker Solar Probe and the upcoming launch of ESA's Solar Orbiter to which NASA is contributing instruments, NASA heliophysics no longer has a flagship mission.
Please do NOT start discussing the merits of various launchers. This is a circa 2030 launch date mission, and we have had this discussion here ad nauseam.
A newish STAR-92 series kick stage or larger would do the trick id think.
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#5
by
theinternetftw
on 23 Nov, 2018 00:10
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A newish STAR-92 series kick stage or larger would do the trick id think.
From the
June 2018 NGIS product catalog [PDF]:
The STAR 92 is a derivative of our successful STAR and CASTOR series of motors. It incorporates the motor heritage of both systems and can be used in either a third-stage or an upper-stage application. This design progressed to the point at which a preliminary design review (PDR) was held.
This page of information is untouched from the
2008 ATK product catalog.So if this is accurate, it needs to be dusted off and given a bit of work.
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#6
by
AegeanBlue
on 24 Nov, 2018 05:39
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I did not know about the STAR 92. Getting NASA to pay for its development would be a major coup for NGIS. Of course 30-95 F will not cut it in this case, so would that mean that it could go in a pressurized vessel Soviet style until it is time to use it? I think not.
All information about this proposal is welcome. Is this just a paper study, to be shelved, or is it a real effort this time? Does heliophysics have another large and less risky priority? Reading this forum you get a sense of how planetary science and astrophysics work. Earth science and heliophysics @ NASA, not so much
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#7
by
theinternetftw
on 24 Nov, 2018 09:18
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I did not know about the STAR 92. Getting NASA to pay for its development would be a major coup for NGIS. Of course 30-95 F will not cut it in this case
The mass is the bigger problem. I was caught up in finding the thing and missed that minor detail. 37,000 lbs that you have to deliver to the sun.
As McFly would say, "This is heavy."
Having now actually had time to look through the entire STAR catalog, it looks something the size of the STAR 63F would be what you would want thrust-wise. But it also looks like the only STARs that have been designed for long-term space thermal loads are the Mars Pathfinder / MER deceleration motors, and those things are tiny.
So the idea I suppose would be to make a STAR 63F sized booster that is rated for cruise like a MER decelerator, then have the rest be up to the Parker-derived TPS seen in the slide deck.
Now all you have to do is throw 5 tons at the sun. Which is about seven times more than Parker. And you have to get twice as close.
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#8
by
Blackstar
on 24 Nov, 2018 12:08
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All information about this proposal is welcome. Is this just a paper study, to be shelved, or is it a real effort this time? Does heliophysics have another large and less risky priority? Reading this forum you get a sense of how planetary science and astrophysics work. Earth science and heliophysics @ NASA, not so much
This is a study that will feed into the next heliophysics decadal survey. Astrophysics has been funding four studies of major telescope projects that will feed into Astro 2020, which is starting up now. Helio will start up in a few years, and they are funding this study, and probably several other large ones. So yeah, it's still at the paper stage, meaning not approved for development. And it won't be approved for development until after the decadal survey says that it should be, and NASA gins up the money for it.
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#9
by
K-P
on 24 Nov, 2018 19:08
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Seems like a good opportunity for an Oumuamua flyby, too.
As this will still be on a powerpoint-stage if and when Planet 9 is found, I'd rather morph it into Planet 9 flyby mission than start a separate project for it.
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#10
by
hektor
on 24 Nov, 2018 20:16
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Pick your favorite Transneptunian.
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#11
by
K-P
on 25 Nov, 2018 19:08
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Pick your favorite Transneptunian.
Voyager 1.
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#12
by
AegeanBlue
on 28 Nov, 2018 05:54
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#13
by
Blackstar
on 14 Dec, 2018 16:51
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#14
by
AegeanBlue
on 14 Dec, 2018 22:27
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Thank you Blackstar. Was there any discussion in the session?
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#15
by
AegeanBlue
on 14 Dec, 2018 22:51
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#16
by
vjkane
on 15 Dec, 2018 15:32
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It appears that for the early studies, the team is using the New Horizons design as its strawman. I presume that a real design would include multiple RTGs -- Pu-238 has a half life of 87.74 years; the nominal 50 year mission is a significant fraction of that.
From presentations that I've read, the driving factor in loss of power for current missions is the degradation of the thermo- electric couples. The eMMRTG development program would use a new design for the couples that at the end of a nominal 14 year mission increases power by 50%. A 50 year mission might want to further address this issue.
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#17
by
Blackstar
on 09 Jan, 2019 14:49
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#18
by
K-P
on 09 Jan, 2019 15:23
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Besides politics, why use single launch SLS as a baseline launcher? (per slides)
How about launching cruise stages/modules separately (with cheaper yet capable launchers) and dock them autonomously in Earth orbit before departure? Could be less expensive yet more capable mission?
Why it seems docking and multiple launch scenarios are limited only to human missions planning...?
And while we go down this road, why not create a fleet of similar mini probes (economy of volumes) and launch them together and let them take their unique trajectories to various KBO targets only at the point of JGA? We have plenty of examples of having great "1-2 punches" of succesful probe twins in solar system exploration.
edit: removed alternative launcher names to avoid too obvious amazing peopleism...
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#19
by
Blackstar
on 09 Jan, 2019 17:57
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#20
by
AegeanBlue
on 27 Feb, 2019 23:19
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#21
by
AegeanBlue
on 13 May, 2019 22:21
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#22
by
gosnold
on 14 May, 2019 15:43
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There was a presentation at the most recent OPAG (April 2019):
https://www.lpi.usra.edu/opag/meetings/apr2019/presentations/Paul.pdf
So reading page 21, the fastest way out of the Solar system seems to be doing a Jupiter anti gravity assist to drop the perigee to 4 solar radius, then do an Oberth maneuver at the perigee with a Castor 30XL. That gets 12.5 AU/year.
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#23
by
redliox
on 14 May, 2019 21:37
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Is there a preferred direction as to where an Interstellar probe should head? I don't refer to a specific star, but the "nose" versus "tail" directions the Sun is traveling...not to mention the Ice Giants and KBOs a few scientists hope to mix in as a bonus. There appears to be a slightly richer mix of targets toward the "tail," like Uranus (ironically) and 5 KBOs, the later including Eris and Varuna as a stretch. Once the probe has a direction post gravity-assists (be it Solar or Jovian), it will be stuck with that direction on way or another. How will they decide this?
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#24
by
JH
on 14 May, 2019 21:50
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The heliotail is thousands of AU long, so it would take hundreds of years to escape the heliosphere, even at 12.5 AU/year.
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#25
by
AegeanBlue
on 14 May, 2019 22:42
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Is there a preferred direction as to where an Interstellar probe should head? I don't refer to a specific star, but the "nose" versus "tail" directions the Sun is traveling...not to mention the Ice Giants and KBOs a few scientists hope to mix in as a bonus. There appears to be a slightly richer mix of targets toward the "tail," like Uranus (ironically) and 5 KBOs, the later including Eris and Varuna as a stretch. Once the probe has a direction post gravity-assists (be it Solar or Jovian), it will be stuck with that direction on way or another. How will they decide this?
If you see the presentation they are actively exploring several destinations. The probe will flyby an outer solar body beyond Jupiter. It is simply not that often that something gets sent so far out and they would like the support of the planetary community considering the probe will most likely come with a $1+ bn price tag. All of the workshops are intended to build a consensus among various communities as what would be the best target and trajectory.
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#26
by
AegeanBlue
on 01 Nov, 2019 15:04
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#27
by
AegeanBlue
on 13 Nov, 2019 18:04
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#28
by
AegeanBlue
on 14 Mar, 2021 05:27
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#29
by
vjkane
on 14 Mar, 2021 17:15
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The presentations from this conference last fall has a lot of information on the current thinking.
They are currently thinking of a spinning spacecraft (makes sense for a mission so focused on fields and particles). The downside is that it would compromise any studies of a dwarf planet by an imager or spectrometer. They are investigating a camera that would be placed at at the rear of the spacecraft (opposite side of the antenna) on the spin axis. That would enable approach imaging, but there would likely be smear problems limiting resolution.
http://interstellarprobe.jhuapl.edu/Resources/Meetings/agenda.php?id=112
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#30
by
russianhalo117
on 14 Mar, 2021 19:02
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The presentations from this conference last fall has a lot of information on the current thinking.
They are currently thinking of a spinning spacecraft (makes sense for a mission so focused on fields and particles). The downside is that it would compromise any studies of a dwarf planet by an imager or spectrometer. They are investigating a camera that would be placed at at the rear of the spacecraft (opposite side of the antenna) on the spin axis. That would enable approach imaging, but there would likely be smear problems limiting resolution.
http://interstellarprobe.jhuapl.edu/Resources/Meetings/agenda.php?id=112
they are also weighing the option of a spin table for certain instruments while the rest of the spacecraft is not spun to carry the remaining instruments.
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#31
by
vjkane
on 14 Mar, 2021 22:40
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They are currently thinking of a spinning spacecraft (makes sense for a mission so focused on fields and particles). The downside is that it would compromise any studies of a dwarf planet by an imager or spectrometer. They are investigating a camera that would be placed at at the rear of the spacecraft (opposite side of the antenna) on the spin axis. That would enable approach imaging, but there would likely be smear problems limiting resolution.
http://interstellarprobe.jhuapl.edu/Resources/Meetings/agenda.php?id=112
they are also weighing the option of a spin table for certain instruments while the rest of the spacecraft is not spun to carry the remaining instruments.
I had forgotten about the potential spin (or despin) table; more recent presentations I've seen haven't mentioned it, but I don't know if it's been dropped from consideration.
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#32
by
AegeanBlue
on 15 Mar, 2021 07:16
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While I have not read each and every presentation, those that I read paint a pretty mature design compared to 2018/9 when I started this thread. The solar Oberth manuever is the least mature/least desirable option, though they will give it a few more months for trade space studies. Still, my feeling is that if the mission does not get approved now and they decide to punt towards the next astrophysics decadal in another decade, then it might happen because they will do studies and experiments inbetween to increase TRL. Otherwise we are talking about a mission launched on SLS Block 2 plus Centaur plus possibly a STAR48. Jupiter Gravity Assist either powered or not means a spacecraft that moves 7 to 8 AU per year. Most likely TNO target seems to be Quaoar, which it will encounter 7 years after launch. Spin or non spin selection affects quality of data at the flyby target AND the telecommunications option, Ka band requires too high a pointing precision for a spinning spacecraft compared to X band. Primary pointing target seems to be the IBEX ribbon, which is compatible with a Quaoar flyby. Honestly with sufficient engineering and science conservatism this can be built without turning into the next JWST. The question is would JHUAPL be available to build or would it get oversubscribed as JPL currently is should this be approved. I read with interest on the Uranus/Neptune threads how JPL is simply incapable of doing those missions on top of everything else it is already doing.
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#33
by
Blackstar
on 15 Mar, 2021 14:41
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Still, my feeling is that if the mission does not get approved now and they decide to punt towards the next astrophysics decadal in another decade
This is a heliophysics mission. It can only happen if the heliophysics decadal survey ranks it a high priority, and even then, it's too expensive for the heliophysics budget alone to fund it. In order to get a sense of the potential timeline, you might work out when the next helio decadal will take place and work from there.
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#34
by
gosnold
on 15 Mar, 2021 17:56
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Still, my feeling is that if the mission does not get approved now and they decide to punt towards the next astrophysics decadal in another decade
This is a heliophysics mission. It can only happen if the heliophysics decadal survey ranks it a high priority, and even then, it's too expensive for the heliophysics budget alone to fund it. In order to get a sense of the potential timeline, you might work out when the next helio decadal will take place and work from there.
Could a mission designed for a KBO flyby launch sooner, with the support of the planetary community?
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#35
by
Blackstar
on 15 Mar, 2021 18:04
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Still, my feeling is that if the mission does not get approved now and they decide to punt towards the next astrophysics decadal in another decade
This is a heliophysics mission. It can only happen if the heliophysics decadal survey ranks it a high priority, and even then, it's too expensive for the heliophysics budget alone to fund it. In order to get a sense of the potential timeline, you might work out when the next helio decadal will take place and work from there.
Could a mission designed for a KBO flyby launch sooner, with the support of the planetary community?
It's the other way around--this is a heliophysics mission that would need the support of the planetary and astro communities to get funding. And those communities are going to ask if the cost they would be asked to pay is worth whatever science they would get out of the mission.
(Sidenote: I'm currently involved in both of those decadal surveys, and I also know one of the IP leaders, so I have some perspective on this stuff.)
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#36
by
lrk
on 15 Mar, 2021 21:21
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Has solar thermal propulsion been considered for this mission? Basically the idea is to use heat from the sun to boil and superheat liquid hydrogen. Could allow for a nuclear thermal-like Isp for the near-sun Oberth effect burn, instead of pushing a heavy, low-Isp solid motor all the way to Jupiter and back.
TRL is lower than using a solid kick stage, as keeping the LH2 from boiling off during the multi-year coast and approach to the sun would be a challenge, but the actual solar thermal engine should be pretty straightforward (heat exchanger + nozzle). And with more than double the potential Isp of a solid it seems to merit consideration.
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#37
by
jbenton
on 16 Mar, 2021 00:19
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Has solar thermal propulsion been considered for this mission? Basically the idea is to use heat from the sun to boil and superheat liquid hydrogen. Could allow for a nuclear thermal-like Isp for the near-sun Oberth effect burn, instead of pushing a heavy, low-Isp solid motor all the way to Jupiter and back.
TRL is lower than using a solid kick stage, as keeping the LH2 from boiling off during the multi-year coast and approach to the sun would be a challenge, but the actual solar thermal engine should be pretty straightforward (heat exchanger + nozzle). And with more than double the potential Isp of a solid it seems to merit consideration.
Yes, they're considering it right now. According to my interpretation of the article posted upthread, (which could be mistaken) they're not sure that they could do the Solar Oberth maneuver without it. It also has the added benefit of cooling the thermal shield to within acceptable parameters:
JHUAPL is testing materials for an Oberth maneuver around the Sun and solar thermal propulsion at the JHU campus using the same solar simulator they used for Parker Solar Probe:
https://hub.jhu.edu/magazine/2021/spring/apl-interstellar-probe/
EDIT: I wanted to quote a part of the article:
To cool and preserve the integrity of the heat shield, the researchers made the conceptual breakthrough of incorporating tiny channels filled with hydrogen gas into the shield's bulk. During the probe's searing slingshot around the sun, the gas would heat up, expand, and course through the channels that all lead to a single exhaust nozzle. "The idea is to absorb all this heat with hydrogen," Benkoski says, "and shoot it out the back of the probe." In this way, the cooling setup also opportunistically doubles as an engine, thus supplying the thrust needed to complete the Oberth maneuver in the first place.
...
With this theoretical solution, the researchers had actually stumbled onto an old idea, called solar thermal propulsion. Although kicked around since the 1960s as a combustion-free way to enable space travel, it has never panned out. Thanks to advances in materials science and engineering, Benkoski and colleagues newly demonstrated the concept's feasibility with the first-ever solar thermal propulsion engine prototype.
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#38
by
AegeanBlue
on 16 Mar, 2021 21:10
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Mea cupla, it is heliophysics, not astrophysics. Considering the Greek Solar (sorry, need to stop here for a second and just say that I have to use stupid words to get my point across. I know that means I must have a weak argument, but that's why I use bad words)., I could offer to help translate any petition from the general public into Greek, but then again all of them do speak and read English and from what I understand, they are not the ones that need convincing.
In the previous decadal Parker Solar Probe, that had not yet been named after Eugene Parker, was consuming community resources. Nowadays my understanding is that there are no heliophysics flagships being actively developed, so I see this more likely to happen than 10 years. Then again I am a member of the public, not an insider.
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#39
by
AegeanBlue
on 27 Apr, 2021 05:48
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#40
by
jbenton
on 27 Apr, 2021 22:57
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This Interstellar Probe Would Go Deeper Into Space Than Anything Before it
https://gizmodo.com/this-interstellar-probe-would-go-deeper-into-space-than-1846767272
Apparently there was a presentation at the EGU
The article seems to suggest that they're no longer considering a Solar gravity assist, is this the case?
To get out there at such a clip, the team proposes slingshotting the probe around Jupiter, in a manner akin to Cassini. That beats shooting the probe past the Sun, where it would need a massive heat shield to survive, cutting down the number of scientific instruments the craft could take on its journey.
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#41
by
vjkane
on 27 Apr, 2021 23:43
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The article seems to suggest that they're no longer considering a Solar gravity assist, is this the case?
That seems to be the case. Here's a statement from the abstract for a talk from the EGU meeting: "Together with the Space Launch System (SLS) Office at the NASA Marshall Space Flight Center, the team has analyzed dozens of launch configurations and demonstrate that asymptotic speeds in excess of 7.5 Astronomical Units (AU) per year can be achieved using existing or near-term propulsion stages with a powered or passive Jupiter Gravity Assist (JGA). These speeds are more than twice that of the fastest escaping man-made spacecraft to date, which is Voyager 1 currently at 3.59 AU/year. An Interstellar Probe would therefore reach the Termination Shock (TS) in less than 12 years and cross the Heliopause into the VLISM after about 16 years from launch."
Depending on SLS or similar capacity commercial vehicles certainly seems to be lower risk than a close, powered flyby of the sun.
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#42
by
Blackstar
on 28 Apr, 2021 02:35
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Depending on SLS or similar capacity commercial vehicles certainly seems to be lower risk than a close, powered flyby of the sun.
Also, if they do a close, powered slingshot past the sun there is a risk that they could travel back in time. That's fine if you need to retrieve a couple of humpback whales, but that's not their mission.
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#43
by
Redclaws
on 28 Apr, 2021 02:45
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Depending on SLS or similar capacity commercial vehicles certainly seems to be lower risk than a close, powered flyby of the sun.
Also, if they do a close, powered slingshot past the sun there is a risk that they could travel back in time. That's fine if you need to retrieve a couple of humpback whales, but that's not their mission.
And it’s the past anyway - we’ve still got humpbacks.
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#44
by
Vultur
on 28 Apr, 2021 05:17
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Depending on SLS or similar capacity commercial vehicles certainly seems to be lower risk than a close, powered flyby of the sun.
Will there be any SLS available for non-Artemis missions?
I guess they could probably use Starship, though.
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#45
by
b0objunior
on 28 Apr, 2021 06:08
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Depending on SLS or similar capacity commercial vehicles certainly seems to be lower risk than a close, powered flyby of the sun.
Will there be any SLS available for non-Artemis missions?
I guess they could probably use Starship, though.
An empty moon starship would give you a hell of a boost fully fuelled.
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#46
by
lrk
on 28 Apr, 2021 16:22
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Depending on SLS or similar capacity commercial vehicles certainly seems to be lower risk than a close, powered flyby of the sun.
Will there be any SLS available for non-Artemis missions?
I guess they could probably use Starship, though.
An empty moon starship would give you a hell of a boost fully fuelled.
Elon has previously mentioned potentially developing a kick stage powered by a single R-vac that could be deployed from Starship in a highly elliptical orbit. Can't recall how recently that was suggested, though.
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#47
by
Star One
on 08 May, 2021 10:35
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EGU Press Release:
Probing deep space with InterstellarMUNICH -- When the four-decades-old Voyager 1 and Voyager 2 spacecraft entered interstellar space in 2012 and 2018, respectively, scientists celebrated. These plucky spacecraft had already traveled 120 times the distance from the Earth to the sun to reach the boundary of the heliosphere, the bubble encompassing our solar system that's affected by the solar wind. The Voyagers discovered the edge of the bubble but left scientists with many questions about how our Sun interacts with the local interstellar medium. The twin Voyagers' instruments provide limited data, leaving critical gaps in our understanding of this region.
NASA and its partners are now planning for the next spacecraft, currently called the Interstellar Probe, to travel much deeper into interstellar space, 1,000 astronomical units (AU) from the sun, with the hope of learning more about how our home heliosphere formed and how it evolves.
"The Interstellar Probe will go to the unknown local interstellar space, where humanity has never reached before," says Elena Provornikova, the Interstellar Probe heliophysics lead from the Johns Hopkins Applied Physics Lab (APL) in Maryland. "For the first time, we will take a picture of our vast heliosphere from the outside to see what our solar system home looks like."
Provornikova and her colleagues will discuss the heliophysics science opportunities for the mission at the European Geosciences Union (EGU) General Assembly 2021.
The APL-led team, which involves some 500 scientists, engineers, and enthusiasts -- both formal and informal -- from around the world, has been studying what types of investigations the mission should plan for. "There are truly outstanding science opportunities that span heliophysics, planetary science, and astrophysics," Provornikova says.
Some mysteries the team hopes to solve with the mission include: how the sun's plasma interacts with interstellar gas to create our heliosphere; what lies beyond our heliosphere; and what our heliosphere even looks like. The mission plans to take "images" of our heliosphere using energetic neutral atoms, and perhaps even "observe extragalactic background light from the early times of our galaxy formation -- something that can't be seen from Earth," Provornikova says. Scientists also hope to learn more about how our sun interacts with the local galaxy, which might then offer clues as to how other stars in the galaxy interact with their interstellar neighborhoods, she says.
The heliosphere is also important because it shields our solar system from high-energy galactic cosmic rays. The sun is traveling around in our galaxy, going through different regions in interstellar space, Provornikova says. The sun is currently in what is called the Local Interstellar Cloud, but recent research suggests the sun may be moving toward the edge of the cloud, after which it would enter the next region of interstellar space -- which we know nothing about. Such a change may make our heliosphere grow bigger or smaller or change the amount of galactic cosmic rays that get in and contribute to the background radiation level at Earth, she says.
This is the final year of a four-year "pragmatic concept study," in which the team has been investigating what science could be accomplished with this mission. At the end of the year, the team will deliver a report to NASA that outlines potential science, example instrument payloads, and example spacecraft and trajectory designs for the mission. "Our approach is to lay out the menu of what can be done in such a space mission," Provornikova says.
The mission could launch in the early 2030s and would take about 15 years to reach the heliosphere boundary -- a pace that's quick compared to the Voyagers, which took 35 years to get there. The current mission design is planned to last 50 years or more.
https://www.eurekalert.org/pub_releases/2021-04/egu-pds042221.php
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#48
by
AegeanBlue
on 15 Nov, 2021 21:10
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#49
by
Orionwillstay
on 14 Dec, 2021 04:05
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#50
by
Blackstar
on 14 Dec, 2021 11:47
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Fresh from the oven - Interstellar Probe Mission Concept Report (Dec 13, 2021)
https://interstellarprobe.jhuapl.edu/Interstellar-Probe-MCR_V4_for-posting.pdf
I know the main author on that study and have worked with him on a number of projects. Nice guy. He has a big collection of studies of this concept going back decades. Now that the heliophysics community has its solar probe, this is the next big mission on their wish list. But I suspect that this is just not a realistic mission. The cost is high, the timeline is really long (decades before it returns data), and the heliophysics program is not funded at the level required to build such a mission.
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#51
by
Welsh Dragon
on 14 Dec, 2021 12:28
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I love this concept but are they seriously expecting SLS-Centaur to be a thing? I'm not being facetious, just wondering about the thought process. What is the purpose of a study when it assumes a launch vehicle that is very unlikely to materialise? Just to show what could be possible? Or to influence the powers that be into nudging that launch vehicle configuration closer to reality? Or are they actually working on the assumption it'll be a thing?
(Note, haven't yet gone through the whole thing, only seen that all three trajectory options considered had the same launch vehicle assumption, maybe others are addressed elsewhere.)
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#52
by
Blackstar
on 14 Dec, 2021 15:44
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Don't get caught up on launch vehicles. In studies like this, they are intended to be representative, not literal.
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#53
by
Eric Hedman
on 14 Dec, 2021 18:52
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The issue I have with this is the timeline. The document said that this could be sending data for fifty years. It will take ten years to get where its real mission starts. In that time frame there might be higher speed options available options and newer probes might be shooting past it twenty five to thirty years out. I know we have a couple of probes sending data 40+ years out. But that is a secondary unexpected bonus to those missions.
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#54
by
gosnold
on 14 Dec, 2021 19:09
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It's very interesting to see how it has matured over the years. They started with innovative ideas like solar thermal propulsion, ie running some liquid propellant through a heat shield to get an Oberth boost with a perihelion of 2 solar radii or less, and in the end they go for a super simple solution of just kicking the probe out of Earth orbit as fast as possible and using an unpowered Jupiter gravity assist. Similarly they have removed the optical comms package.
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#55
by
briantipton
on 14 Dec, 2021 20:49
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The issue I have with this is the timeline. The document said that this could be sending data for fifty years. It will take ten years to get where its real mission starts. In that time frame there might be higher speed options available options and newer probes might be shooting past it twenty five to thirty years out. .
I have the same concern. Given that this is not a cheap mission ($1.7B + launch costs, which would be very high using the notional concept described), I find the proposed 7AU/yr exit velocity underwhelming. 60 years after Voyager and the best we can do is twice as fast? Maybe that is true for a conservatively design mission today, but if we wait 10 years to develop a proposal around the expected capabilities for a mid 2040s launch, maybe an exit velocity of 10-15 AU/yr would be achievable (I'd like to believe it will be). Granted, if I were a member of the heliophysics community, I probably wouldn't advocate doing nothing in the near term because something better might be coming, but in a world of budget constrained science, this just doesn't seem like the opportune time for this mission.
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#56
by
Blackstar
on 14 Dec, 2021 22:24
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The issue I have with this is the timeline. The document said that this could be sending data for fifty years. It will take ten years to get where its real mission starts. In that time frame there might be higher speed options available options and newer probes might be shooting past it twenty five to thirty years out. I know we have a couple of probes sending data 40+ years out. But that is a secondary unexpected bonus to those missions.
Except that we live in the real world with current physics. One can always posit that maybe
someday in the future we'll have faster transportation options. But that's an argument for sitting around doing nothing. Someday I'll have a flying car, so why should I walk to the store today to buy milk?
There are other problems with the timeline, however. One is how long it will take before the spacecraft starts returning meaningful data. Will the principal investigators still be alive? Another problem is the political support for something that takes so long to return data. When you add in how long it will take to develop the spacecraft (10-15 years?) and then how long until it returns data, the timeline starts to work against you for political support. Somebody will ask if there are other things that could be funded and flown faster.
Note that heliophysics is not the only field facing this. Look at the astrophysics decadal survey and their calculations of how long it will take to fund things for development. Look at the travel times to the outer planets for planetary science. These projects are increasingly generational, because we've done the closer and easier things.
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#57
by
briantipton
on 14 Dec, 2021 23:21
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The issue I have with this is the timeline. The document said that this could be sending data for fifty years. It will take ten years to get where its real mission starts. In that time frame there might be higher speed options available options and newer probes might be shooting past it twenty five to thirty years out. I know we have a couple of probes sending data 40+ years out. But that is a secondary unexpected bonus to those missions.
Except that we live in the real world with current physics. One can always posit that maybe someday in the future we'll have faster transportation options. But that's an argument for sitting around doing nothing. Someday I'll have a flying car, so why should I walk to the store today to buy milk?
Or it is an argument for
developing the capabilities so that future missions can use them. The Astrophysics Decadal Survey recommended that developing the capabilities for the next Flagship observatory to fly in the 2040s makes more sense than building a compromised Flagship in the 2030s. Elon wants to colonize Mars, so he invests in drastically reducing the cost of transport to Mars with Starship, rather than trying to colonize Mars with Falcon Heavy. Maybe the priority right now should be on developing the capability for high C3 missions, not launching one with what we have. This is NOT, of course, any one group of scientists can cause to happen, so of course they need to propose missions compatible with "near-existing" launch vehicles, as the report puts it.
Of course, getting political support for NASA to work on this capability would be a huge challenge, but maybe if the money gets spent in the right congressional districts if could happen
. I don't know what the best solution for high C3 missions in the middle of this century should be - something exotic like NEP or the solar Oberth proposal? Or something more mundane? I haven't taken the time to do the math myself, or search the web for someone who has, but what would something like a fully fueled Centaur V+Star48G launched to C3~40km^2/s^2 by a Starship refueled in LEO be capable of? That doesn't seem anymore of a stretch than the notional launcher in the JHUAPL study, and I think it would be more capable.
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#58
by
zubenelgenubi
on 14 Dec, 2021 23:55
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The issue I have with this is the timeline. The document said that this could be sending data for fifty years. It will take ten years to get where its real mission starts. In that time frame there might be higher speed options available options and newer probes might be shooting past it twenty five to thirty years out. I know we have a couple of probes sending data 40+ years out. But that is a secondary unexpected bonus to those missions.
Except that we live in the real world with current physics. One can always posit that maybe someday in the future we'll have faster transportation options. But that's an argument for sitting around doing nothing. Someday I'll have a flying car, so why should I walk to the store today to buy milk?
Or it is an argument for developing the capabilities so that future missions can use them.
Two issues, neither trivial nor insurmountable.
One
New propulsion systems are beyond the scope of a scientific spacecraft study, and studies on the bureaucratic level of a decadal survey.
It verges on or crosses over into national or supranational political directives, requiring steady support for years or decades.
The project is now a semi-permanent fixture on the national or world stage, something that will consume a multitude of career-lives, but neither protects citizens from their foes, nor feeds the several endless versions of Great Society programs in First World nations.
Welcome aboard.
Two
Who pays for the development costs? It could total billions of dollars or euros. No scientific discipline will willingly surrender their funding for years or longer for this.
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#59
by
briantipton
on 15 Dec, 2021 00:03
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Note that heliophysics is not the only field facing this. Look at the astrophysics decadal survey and their calculations of how long it will take to fund things for development. Look at the travel times to the outer planets for planetary science. These projects are increasingly generational, because we've done the closer and easier things.
Yes, outer planets proposals are also just begging for a better high C3 launch capability. It is always going to take a long time to get to the outer planets, but I find it particularly frustrating to see proposals that add 4 or more years to that time in the inner solar system grabbing delta V with multiple gravity assists because we lack the capability to send them on more direct paths (NOT looking at you Europa Clipper - 3 extra years to avoid the cost/availability risk of SLS seems a smart trade). I'm excited by the idea of the proposed outer planets missions, but right now I'd rather we focus on inner solar system missions while we invest in capabilities that enable better (bigger and/or faster) outer system missions.
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#60
by
briantipton
on 15 Dec, 2021 00:15
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The issue I have with this is the timeline. The document said that this could be sending data for fifty years. It will take ten years to get where its real mission starts. In that time frame there might be higher speed options available options and newer probes might be shooting past it twenty five to thirty years out. I know we have a couple of probes sending data 40+ years out. But that is a secondary unexpected bonus to those missions.
Except that we live in the real world with current physics. One can always posit that maybe someday in the future we'll have faster transportation options. But that's an argument for sitting around doing nothing. Someday I'll have a flying car, so why should I walk to the store today to buy milk?
Or it is an argument for developing the capabilities so that future missions can use them.
Two issues, neither trivial nor insurmountable.
One
New propulsion systems are beyond the scope of a scientific spacecraft study, and studies on the bureaucratic level of a decadal survey.
It verges on or crosses over into national or supranational political directives, requiring steady support for years or decades.
Two
Who pays for the development costs? It could total billions of dollars or euros. No scientific discipline will willingly surrender their funding for years or longer for this.
Absolutely agree with both points. In the world we live in, with the decision making process we have, everyone is doing what they can to get the best science done with the funds available. What I suggest is, if NASA wants to step up to the challenge, then money invested in some increased capability for high energy trajectories might be money well spent. It's not like this is unheard of - SEP was once a "wouldn't it be nice to have" technology, but now it is on the table for any mission that would benefit from it. It just seems to me that our high C3 capability is becoming a limitation on pushing on to the next level mission. Compare this to our capability to launch to LEO, which has become much more affordable in recent years for both large and small sats due certain new space companies.
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#61
by
VSECOTSPE
on 15 Dec, 2021 01:23
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The length of many NASA programs vice the political cycle is an issue. In the early aughts (200X), I had a boss at OMB who complained that it was easy to get White House political appointees excited about a new mission, but he’d lose their interest as soon as the schedule was discussed.
Partly to mitigate this issue, we did fund an advanced propulsion program within NASA’s old Space Science Enterprise. It was led by Les Johnson out of MSFC and looked at everything from electrodynamic tethers to nuke thermal and nuke electric in an effort to, among other things, get mission trip times down. (Les is also a published sci-fi author.)
But the perennial problem with advanced propulsion and other technology investments at NASA is that overruns on flight programs in development and operation usually eat that seed corn before it can bear fruit. This is largely what happened to the advanced propulsion initiative. When STS fly out costs kept rising after the VSE and ESAS carved out an even larger funding wedge for Ares I/Orion than what was made available in the VSE, advanced propulsion in the Space Science Enterprise was one of many longer-term investments that felt the axe.
To Les’s credit, a little of that prior investment is seeing the light of day in a couple solar sail missions: Solar Cruiser and the NEA Scout. But that’s more low-hanging fruit than the technology push envisioned by that initiative to address the C3/trip time issues mentioned in this thread.
Nowadays, long-term propulsion investment at NASA is haphazard or non-existent. Today’s Space Technology Mission Directorate should have an integrated, funded plan in this (and other technology) areas. But they can’t seem to set priorities or get funding traction, so their budget mostly consists of SBIR grants and a few outsized earmarks. (One of these earmarks is for nuke thermal research at MSFC, but it is level-funded, opposed by the current and prior Administration, and going nowhere fast, as most earmarks do.)
I may be naive, but I think an argument could be made to stakeholders that the MSFC workforce could be much healthier and stable pursuing long-term propulsion investments that industry is not making, vice competing very poorly against industry HLVs. Similar arguments could be made in other technology areas for other field centers. But no NASA Administrator has come forward with such an argument, and strategic workforce planning is practically nonexistent in the agency.
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#62
by
Don2
on 16 Dec, 2021 19:41
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I think you need to be careful about developing highly specialized technology for a very small market. How many missions a decade fly to the outer solar system? Maybe two. There isn't a big demand for high C3 capabilities, and much of the needs can be met by gravity assists. Those aren't free when you account for the additional operational costs of longer missions, but they tend to be very cheap compared to propulsion systems.
Scientists will always spend money on science rather than tech development when they can. The interstellar probe team has found a way to do the science they want without too much new technology. Interstellar probe does offer quite a lot for the money. Orcus has a diameter of 910km and show signs of fresh ice on the surface, indicating recent cyrovolcanism. It has a large moon Vanth, diameter 434km, making it similar to a smaller version of the Pluto-Charon system. To collect data would require adding modernized equivalents of LORRI and Ralph from New Horizons, which would need 19.1 kg out of the total probe payload of 87 kg. If planetary science cancelled a Discovery competition, maybe then they could buy in to Interstellar Probe for $800 million. Getting a look at a KBO for $800 million might be attractive relative to other Discovery program opportunities. Or maybe not, given how creative Discovery proposers tend to be.
As I see it, the main problem for Interstellar probe has nothing to do with technology. It is competition from other projects. Ice Giants are more important than KBOs, so an ice giant orbiter will be funded ahead of a KBO mission. Cometary sample return has been a desire for decades, and it now seems to be possible with a New Horizons class budget. That probably also gets funded ahead of KBOs.
If Congress decides that new propulsion technology is a strategic need like they decided that SLS is a strategic need then an interstellar probe would be an excellent opportunity to demonstrate the capabilities of the technology. However, science shouldn't pay for it because science can make do without it, just like science is making do without SLS.
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#63
by
Blackstar
on 16 Dec, 2021 20:31
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As I see it, the main problem for Interstellar probe has nothing to do with technology. It is competition from other projects. Ice Giants are more important than KBOs, so an ice giant orbiter will be funded ahead of a KBO mission. Cometary sample return has been a desire for decades, and it now seems to be possible with a New Horizons class budget. That probably also gets funded ahead of KBOs.
It's more complex than that--all these big projects don't compete with each other. It's not like NASA decides "now we will build a big telescope and we won't build an expensive planetary mission." That kind of trade-off used to happen more often in the 1970s and 1980s when NASA could really only put up one big expensive new start at a time.
Nowadays, these projects are all happening within their specific space science areas that are
mostly walled off from each other. (Yeah, JWST ultimately took some money from other areas, but I would not go too far down that argument.) The problem for solar and space physics--aka heliophysics--is that it has a much smaller overall budget. That means that any really big project that comes along is harder to fund in heliophysics. The proponents of this interstellar probe mission have been making the case for a long time now that they can get support for it from astrophysics and planetary science. But it's not clear that those other areas will actually agree to spend their own money on this mission. That's where something like imaging a new KBO comes into play--the planetary scientists may not be all that interested in doing that.
Something that I've mentioned before in the astro decadal thread is that one of the reasons these missions may have big price tags is not because the scientists advocating them are delusional, but because the projects are
aspirational. They know that they won't get more money if they don't ask for more money. And in fact, that has been an issue for heliophysics in the past. There's a view by some well-placed and knowledgeable people (I'll let you guess) that the last heliophysics decadal survey made a major error by not aiming higher and proposing a big expensive mission. Because they did not do that, their budget did not grow. So the people preparing mission proposals for the next heliophysics decadal survey may be hearing the message that they should aim higher and not feel so constrained by budgets as in the past.
Now naturally this is a balancing act. One of the problems that happened during the 2010 planetary decadal survey was that the Jupiter Europa Orbiter mission that was proposed was just too big to fund. It couldn't get past the decadal survey. The steering committee could not propose something that expensive because it was simply too big compared to the rest of the planetary budget (I was in those decadal survey meetings and I still remember the hand-wringing). So the decadal survey told NASA to de-scope that mission before approving it, and that's how we got to Europa Clipper.
So yeah, there's a on-the-one-hand-on-the-other-hand aspect to how much these proposed missions can cost.
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#64
by
VSECOTSPE
on 16 Dec, 2021 23:34
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I think you need to be careful about developing highly specialized technology for a very small market. How many missions a decade fly to the outer solar system? Maybe two. There isn't a big demand for high C3 capabilities, and much of the needs can be met by gravity assists. Those aren't free when you account for the additional operational costs of longer missions, but they tend to be very cheap compared to propulsion systems.
As always, it depends on the cost/benefit. Propulsion that costs a dime, enables planetary science trip times that stakeholders will buy, and is applicable/scalable to other missions and uses? Sure, bring it on. Propulsion that carries huge fixed costs and enables only one or two potential missions? Probably not.
That’s why we started investing in a portfolio back in the aughts. We didn’t presume to know the winner(s) five or ten years out. (I’ve also been on the other side and advocated for specific propulsion technologies and solutions in competitive selection processes, but that’s where those judgements should be made.)
As I see it, the main problem for Interstellar probe has nothing to do with technology. It is competition from other projects. Ice Giants are more important than KBOs, so an ice giant orbiter will be funded ahead of a KBO mission. Cometary sample return has been a desire for decades, and it now seems to be possible with a New Horizons class budget. That probably also gets funded ahead of KBOs.
IP does not compete with planetary missions. IP competes with other solar and space physics missions that mainly measure the Sun and its interactions with the Earth. For better or worse, those missions will almost always be ranked more important than the Sun’s interactions with the interstellar medium, will almost always have more interest from the community, and will almost always be a lot less expensive.
If Congress decides that new propulsion technology is a strategic need like they decided that SLS is a strategic need then an interstellar probe would be an excellent opportunity to demonstrate the capabilities of the technology. However, science shouldn't pay for it because science can make do without it, just like science is making do without SLS.
Despite the claims of the annoying pop-up ads on SpaceNews, let’s not pretend that there is anything strategic about SLS.
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#65
by
LouScheffer
on 17 Dec, 2021 01:10
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I think you need to be careful about developing highly specialized technology for a very small market. How many missions a decade fly to the outer solar system? Maybe two. There isn't a big demand for high C3 capabilities, and much of the needs can be met by gravity assists.
Maybe just use existing technology in a brute force way? Take an entire
Minotaur-C solid rocket booster and stuff it in the StarShip cargo bay. It's 73 tonnes, and while StarShip could not take it to GTO (Elon estimates 40-50 tonnes to GTO) it can likely do LEO + 1000 m/s. The Minotaur can add about 9000 m/s more, giving LEO + 10000 m/s (C3 = 200) with a 1500 kg payload. Without doing the analysis, this seems about a zillion times easier than a SLS-Centaur-Star48 solution. It's not quite as powerful, but it's close, and it's built from two commercially available parts.
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#66
by
DanClemmensen
on 17 Dec, 2021 01:16
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I think you need to be careful about developing highly specialized technology for a very small market. How many missions a decade fly to the outer solar system? Maybe two. There isn't a big demand for high C3 capabilities, and much of the needs can be met by gravity assists.
Maybe just use existing technology in a brute force way? Take an entire Minotaur-C solid rocket booster and stuff it in the StarShip cargo bay. It's 73 tonnes, and while StarShip could not take it to GTO (Elon estimates 40-50 tonnes to GTO) it can likely do LEO + 1000 m/s. The Minotaur can add about 9000 m/s more, giving LEO + 10000 m/s (C3 = 200) with a 1500 kg payload. Without doing the analysis, this seems about a zillion times easier than a SLS-Centaur-Star48 solution. It's not quite as powerful, but it's close, and it's built from two commercially available parts.
Starship can take a 100 t payload to anywhere in the Solar system. It just needs one or more supporting tanker missions to refuel in LEO. So where do you want your Minotaur-C?
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#67
by
LouScheffer
on 17 Dec, 2021 01:45
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Maybe just use existing technology in a brute force way? Take an entire Minotaur-C solid rocket booster and stuff it in the StarShip cargo bay. It's 73 tonnes, and while StarShip could not take it to GTO (Elon estimates 40-50 tonnes to GTO) it can likely do LEO + 1000 m/s. The Minotaur can add about 9000 m/s more, giving LEO + 10000 m/s (C3 = 200) with a 1500 kg payload. Without doing the analysis, this seems about a zillion times easier than a SLS-Centaur-Star48 solution. It's not quite as powerful, but it's close, and it's built from two commercially available parts.
Starship can take a 100 t payload to anywhere in the Solar system. It just needs one or more supporting tanker missions to refuel in LEO. So where do you want your Minotaur-C?
This option gives you more delta-V (maybe LEO + 16000 m/s or so) but you throw away a StarShip to do so. My option leaves the StarShip in a 200 x 10000 km orbit, or thereabouts. It then lands and lives to launch another day. Typical cost vs delta-V trade.
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#68
by
DanClemmensen
on 17 Dec, 2021 02:16
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Maybe just use existing technology in a brute force way? Take an entire Minotaur-C solid rocket booster and stuff it in the StarShip cargo bay. It's 73 tonnes, and while StarShip could not take it to GTO (Elon estimates 40-50 tonnes to GTO) it can likely do LEO + 1000 m/s. The Minotaur can add about 9000 m/s more, giving LEO + 10000 m/s (C3 = 200) with a 1500 kg payload. Without doing the analysis, this seems about a zillion times easier than a SLS-Centaur-Star48 solution. It's not quite as powerful, but it's close, and it's built from two commercially available parts.
Starship can take a 100 t payload to anywhere in the Solar system. It just needs one or more supporting tanker missions to refuel in LEO. So where do you want your Minotaur-C?
This option gives you more delta-V (maybe LEO + 16000 m/s or so) but you throw away a StarShip to do so. My option leaves the StarShip in a 200 x 10000 km orbit, or thereabouts. It then lands and lives to launch another day. Typical cost vs delta-V trade.
An expendable SS is cheap. The SH will be reusable. The expendable SS could also launch at least two Minotaurs if you need them.
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#69
by
Blackstar
on 17 Dec, 2021 03:01
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And once again, a science thread becomes a "this can be solved with a Starship" thread.
The science section on NSF is increasingly pointless.
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#70
by
DanClemmensen
on 17 Dec, 2021 03:10
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And once again, a science thread becomes a "this can be solved with a Starship" thread.
The science section on NSF is increasingly pointless.
Sorry, I'm somewhat new here. Starship shows up whenever a science thread starts discussing launchers instead of payloads. Maybe you should remind us when the discussion starts to drift into launchers, before the dreaded "Starship" rears its head.
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#71
by
baldusi
on 17 Dec, 2021 03:16
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And once again, a science thread becomes a "this can be solved with a Starship" thread.
The science section on NSF is increasingly pointless.
In their defense, you were arguing whether to invest on new propulsion technology for this mission was worthwhile or not. Name propulsion or delta-v and you get nail as the answer of all the hammers.
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#72
by
Robotbeat
on 17 Dec, 2021 03:55
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I’m a bit sad that a powered solar swingby isn’t the thing. Could get up to 20AU/year.
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#73
by
Hobbes-22
on 17 Dec, 2021 08:10
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As I see it, the main problem for Interstellar probe has nothing to do with technology. It is competition from other projects. Ice Giants are more important than KBOs, so an ice giant orbiter will be funded ahead of a KBO mission. Cometary sample return has been a desire for decades, and it now seems to be possible with a New Horizons class budget. That probably also gets funded ahead of KBOs.
It's more complex than that--all these big projects don't compete with each other. It's not like NASA decides "now we will build a big telescope and we won't build an expensive planetary mission." That kind of trade-off used to happen more often in the 1970s and 1980s when NASA could really only put up one big expensive new start at a time.
Nowadays, these projects are all happening within their specific space science areas that are mostly walled off from each other. (Yeah, JWST ultimately took some money from other areas, but I would not go too far down that argument.) The problem for solar and space physics--aka heliophysics--is that it has a much smaller overall budget. That means that any really big project that comes along is harder to fund in heliophysics. The proponents of this interstellar probe mission have been making the case for a long time now that they can get support for it from astrophysics and planetary science. But it's not clear that those other areas will actually agree to spend their own money on this mission. That's where something like imaging a new KBO comes into play--the planetary scientists may not be all that interested in doing that.
Something that I've mentioned before in the astro decadal thread is that one of the reasons these missions may have big price tags is not because the scientists advocating them are delusional, but because the projects are aspirational. They know that they won't get more money if they don't ask for more money. And in fact, that has been an issue for heliophysics in the past. There's a view by some well-placed and knowledgeable people (I'll let you guess) that the last heliophysics decadal survey made a major error by not aiming higher and proposing a big expensive mission. Because they did not do that, their budget did not grow. So the people preparing mission proposals for the next heliophysics decadal survey may be hearing the message that they should aim higher and not feel so constrained by budgets as in the past.
Now naturally this is a balancing act. One of the problems that happened during the 2010 planetary decadal survey was that the Jupiter Europa Orbiter mission that was proposed was just too big to fund. It couldn't get past the decadal survey. The steering committee could not propose something that expensive because it was simply too big compared to the rest of the planetary budget (I was in those decadal survey meetings and I still remember the hand-wringing). So the decadal survey told NASA to de-scope that mission before approving it, and that's how we got to Europa Clipper.
So yeah, there's a on-the-one-hand-on-the-other-hand aspect to how much these proposed missions can cost.
I've liked a bunch of your posts, but the thumbs-up icon doesn't seem sufficient. So:
Thanks for your continuing contributions to this type of discussion. Your inside perspective elevates these threads from speculation by outsiders (like me) to informative, and I appreciate the effort you're putting into your posts.
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#74
by
edzieba
on 17 Dec, 2021 10:35
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The issue I have with this is the timeline. The document said that this could be sending data for fifty years. It will take ten years to get where its real mission starts. In that time frame there might be higher speed options available options and newer probes might be shooting past it twenty five to thirty years out. I know we have a couple of probes sending data 40+ years out. But that is a secondary unexpected bonus to those missions.
In the 34 years between Pioneer 10 and New Horizons, there has not been an appreciable increase in solar system exit velocity capability, with 77's Voyager 1 still holding the crown. When you're right out at the pointy end of the rocket equation, big changes in mass to orbit do not offer big increases in achievable velocity. There are no near-term propulsion technologies that would offer an appreciable increase in this velocity from propulsion alone (i.e. without sundiving for a big Oberth boost as IP does). NTR would require a dedicated space-only upper stage (enormous gossamer tanks) to take advantage of its ISP boost, nuclear-electric lacks a high power density reactor, and solar-electric lacks power as the probe recedes from the sun (and if you sundive it, you may as well go for Oberth instead).
"Fast new ship overtakes old slow ship" is great for sci-fi plots, but frustratingly lacking in actual rocketry.
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#75
by
su27k
on 17 Dec, 2021 11:39
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This is one mission where LV is critically important, yet we're not supposed to discuss LV?
Good luck getting this off the ground without SHLV and/or advanced propulsion...
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#76
by
LouScheffer
on 17 Dec, 2021 13:26
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And once again, a science thread becomes a "this can be solved with a Starship" thread.
While I appreciate your frustration, "SLS" is mentioned 78 times in the JHU/APL document, so the topic of the launch vehicle is hardly a sideshow.
The science section on NSF is increasingly pointless.
For this mission, more than others, I'd agree. I've been following this forum for many years, and I don't recall a single discussion over the science objectives or implementation of a fields-and-particles mission. Conversely, lots of folks here have interests, opinions, and (sometimes) expertise in planetary exploration, optical astronomy, comm systems, launch vehicles, and so on, so that's the discussion you get, not the science. I'm not even sure where you could find a forum for a robust but informal discussion of the science of a fields-and-particle mission, other than at the bar of a conference on the topic.
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#77
by
Robotbeat
on 17 Dec, 2021 14:05
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But the technical side is interesting beyond just the immediate scientific payback of the mission. Heliospheric science is interesting, but being able to send missions to deeper and deeper space targets (such as Oort Cloud, etc) goes beyond space plasma physics.
There’s nothing wrong with discussing the engineering side. (Which doesn’t mean we should focus just on launch vehicles, which does indeed get a bit tiring.)
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#78
by
Blackstar
on 17 Dec, 2021 14:45
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In the 34 years between Pioneer 10 and New Horizons, there has not been an appreciable increase in solar system exit velocity capability, with 77's Voyager 1 still holding the crown. When you're right out at the pointy end of the rocket equation, big changes in mass to orbit do not offer big increases in achievable velocity. There are no near-term propulsion technologies that would offer an appreciable increase in this velocity from propulsion alone (i.e. without sundiving for a big Oberth boost as IP does). NTR would require a dedicated space-only upper stage (enormous gossamer tanks) to take advantage of its ISP boost, nuclear-electric lacks a high power density reactor, and solar-electric lacks power as the probe recedes from the sun (and if you sundive it, you may as well go for Oberth instead).
"Fast new ship overtakes old slow ship" is great for sci-fi plots, but frustratingly lacking in actual rocketry.
Yup.
And when it comes to actual program/project management, the people who are coming up with the proposals have to plan out timelines for capabilities. One of the questions they ask is what kind of capability will be available by year 5, year 6, year 10? What is the
confidence that this capability will exist by that time when we need it? And is there a way to increase the confidence? So, how much confidence can somebody planning a mission now have that 10 years from now there will be a much better (faster) in-space propulsion system? None of the stuff being worked on in technology labs (better solar electric, solar sails, nuclear thermal) offers a significant improvement in that time frame. And predicting beyond 10 years is even harder for lots of reasons, including the reason that 10 years is a lot of time for a project's budget to get cut. So you have to propose a mission based on assumptions about reasonable capabilities. And the issue of confidence in those capabilities is really important--you cannot really just assume that it will exist, that somebody else (like DARPA or a commercial entity) will develop it. You may have to actually fund it yourself, adding that cost to your project.
There are a lot of other related issues that are down in the weeds. I have not looked at this report, but we recently went through some of that with the planetary science decadal survey. Look up the proposed Pluto orbiter missions and their flight times. Twenty years to get to Pluto. Now what is your confidence that your technology will work at the 20-year mark? I sat in (well, virtually) on some discussions about certifying RTGs to work at 20 years. Do we have an RTG available now that we know with high confidence will work at the 20-year mark? If not, will we have one 5 years from now? Ten years from now? Do we have to start a development project now so that 10 years from now we will have an RTG with a 20-year guaranteed lifetime?* It gets kinda iffy when you have to project missions that far out. All of that stuff enters into consideration for these missions. And there are no magic solutions.
*I actually heard an RTG expert say that this is not that big a problem. But I suspect there are other opinions. You can look at a chart of historical RTG lifetimes and see that some of them did not last very long while others did (I saw that chart--I wonder if I can find it?). The devil is in the details.
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#79
by
VSECOTSPE
on 17 Dec, 2021 15:51
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You can look at a chart of historical RTG lifetimes and see that some of them did not last very long while others did (I saw that chart--I wonder if I can find it?).
The power output of RTGs degrades as a function of Pu238 decay (obviously) and increasing electrical resistance in the thermocouples from thermal stress (cracking), chemical changes (precipitation of dopants onto the thermocouples and sublimation of thermocouple material), and changes in thermal conductivity of the alloys used (changes in metallic structure).
The power output of the old General Purpose Heat Source (GPHS) RTG degrades linearly at ~1.6% per year due to all these effects.
The thermal conductivity of the alloys on the new Multi-Mission (MM) RTG changes non-linearly. Thus, the power output of the MM-RTG degrades more rapidly at the start of operation (~4.7% in the first year of operation) and levels out over time (~2.0% by year 14). However, those alloys are more efficient (convert more heat to electricity) so the MM-RTGs start off with a higher power level per unit of Pu238. And MM-RTGs can be used inside atmospheres while GPHS-RTGs cannot, so for certain missions, there would be no choice even if GPHS-RTGs were still around.
Different missions will make different demands on the lifespan of their RTGs. For a given initial power output, a planetary surface rover may be kaput once the power drops below the level needed to support mobility. That could be, say, 80% of initial power. But a Voyager-type mission may be fine with much smaller percentages of initial power output as long as the DSN can still pick up (or be upgraded to pick up) the spacecraft’s signal.
Finally, Stirling RTGs potentially add mechanical failure modes to what is otherwise a solid-state device. But last I knew, GRC had run the Stirling motor for one of these for a dozen years without issue. It may still be going for all I know.
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#80
by
Hobbes-22
on 17 Dec, 2021 16:57
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The mission report says this about communications:
Contact scheduling and telecommunications begin using the Deep Space Network (DSN) initially; downlink tasks will be performed by the Next Generation Very Large Array (ngVLA) equivalent.
Which piqued my curiosity about the
ngVLA.
The Astronomy and Astrophysics Decadal Survey (Astro2020) of the U.S. National Academy of Sciences has published its report and the Next Generation Very Large Array (ngVLA) received high priority for new ground-based observatories to be constructed during the coming decade. The report, in which ngVLA shared second ranking among ground-based projects, was the culmination of a lengthy process aimed at developing a comprehensive research strategy and vision for a decade of transformative science at the frontiers of astronomy and astrophysics.
The ngVLA is a system of 263 dish antennas spread across the entire extent of North America and concentrated in the U.S. Southwest that will provide dramatic new scientific capabilities to the world’s astronomers. The Astro2020 report led the ground-based facility list with the U.S. Extremely Large Telescope Project (US-ELT), a plan for two large optical telescopes — the Thirty Meter Telescope and the Giant Magellan Telescope, both under different stages of construction. After US-ELT, equal priority was given for development and construction for the ngVLA and the Cosmic Microwave Background Stage-4 experiment (CMB-S4).
In the 21st century, astronomers are imagining the next generation Very Large Array (ngVLA) with 244, 59-foot (18-meter) dishes spread over 5,505 miles (8,860 km). An additional 19 twenty foot (6m) dishes will make up a short-spacing array at the heart of the telescope.
From the
Descanso series of papers on deep-space communications: we could communicate with a Voyager-type spacecraft using the DSN at about 300 AU at 40 bits/s using a 34 m antenna (table 1-1, page 6).
There's precedent; at the Voyager 2 Neptune encounter, the VLA was used:
By far the greatest signal strength improvement for Neptune resulted from arraying the twenty-seven 25-m dishes of the National Radio Astronomy Observatory’s (NRAO) Very Large Array (VLA) near Socorro, New Mexico with the 70-m DSN antenna at Goldstone, California. The received signal power (or data rate capability) with the VLA arrayed with the 70-m DSN antenna was nearly triple that of the 70-m antenna by itself. An array of a 70-m antenna, two 34-m antennas, and the VLA increased the downlink capability by 5.6 dB relative to the 70-m antenna alone, almost a factor of four in bit rate.
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#81
by
Star One
on 21 Dec, 2021 08:28
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#82
by
AegeanBlue
on 25 Dec, 2021 05:16
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When I started this thread 3 years ago I expected the report to be published in 2019, hence the 2019 in the title. I would guess we would need to change the thread title
The Jonathan Amos article is based on the press conference they had on the proposal at the AGU 2021. Here is the video, I would suggest watching it because it answers several questions posed here:
The interstellar probe concept has been studied since the start of the space age. I would dare compare to the human mission to Mars, in that a new study comes out on a periodic or semi-periodic basis, it helps move the concept forward, but for various reasons there is little follow up, most important being cost. In the early space age when space probes did not actually last very long, think Mariner 2 lasting 4 months 7 days from launch, exotic propulsion was likely to get in the mix. Since several people have put here a fantasy proposal of their own, I have my own too: Let's put 10 kilopower reactors, we do have working prototypes on the ground and a 100 kilowatt VASIMR engine, per the most recent press release they had a successful test at 80 KW in July and were expecting 100 KW before the end of the year (it seems that did not happen) and thrust thrust thrust! Then again the experience of the nuclear powered Jupiter Icy Moon Orbiter, which did get the ear of a NASA administrator and a few hundred million for studies that showed that it would cost $16 billion and got cancelled quietly by the next administrator show the need to keep something actually grounded in reality.
The original Grand Tour proposal was for 4 spacecraft to do all 5 outer planets with redundancy, necessary considering the long mission. It was descoped due to cost to the Voyager program of two spacecraft only for Jupiter and Saturn and only for 5 years, since it would get too expensive to develop a spacecraft that would last more than 5 years. Turns out the Voyagers have far exceeded expectations. New Horizons was planned to travel for 9 years until its primary mission, the longest so far in any NASA mission, because by that time a typical satellite around the earth was planned for a 15 year mission so planning for a such a long primary mission would no longer break the bank. It still took public pressure to Congress and Congressional pressure to NASA to get the mission approved. For this probe proposal the team went with "Voyager on steroids" as they called it by basically building on what already has worked and also trying to mitigate issues that have arisen, think of the Voyager technical team that needs to know the long obsolete version of Fortran that Voyager runs.
2036 is the latest launch date where the Jupiter flyby will point to the direction of the solar apex towards where they can study the region of interstellar space that the solar system is headed to. The current launch configuration is SLS Block II + Centaur + STAR 48. They are not wedded to that launch vehicle. As McNutt put it they actually asked around SpaceX, Blue Origin, Ariane and it was only Marshall Space Flight Center that actually gave them detailed characteristics of the super heavy launch vehicle they are developing. They did not mention it at the press conference but a powered Jupiter flyby would require qualifying the STAR-48 to survive 13 months in deep space. The solar Oberth maneuver was rejected because they actually did a full thermal study of a proposed probe based on what they learned with the Parker Solar probe and found that there would be no benefit because of the need to make the probe heat proof, keeping the center of gravity right while the stage is burning etc. Should this mission get approved they have no problem using any rocket capable of giving a C3 of 300 or twice what New Horizons and Parker Solar Probe got
Potential dwarf planet flyby was discussed, with 225088 Gonggong specifically mentioned as a good target, formerly known as 2007 OR10. Also another thing mentioned was a Golden Record which will be a solid state recorder.
Making this study has been so far the most comprehensive interstellar probe study made so far. A very large number of experts were consulted from all over the world. There was a presentation at IAC in Dubai with some 80 people from all over there that were quite excited. International participation would be welcome, but getting it off the ground would also require alignment with the international partner's funding cycle. The report is to go to the heliophysics decadal survey, and if NASA decides to pursue this then a committee to explore the trade space between options (I think the term used was mission definition team but I could be wrong) would be formed, as has happened with previous flagships.
I really want this to happen. Maybe we can convince the Planetary society to lobby for this as they successfully did for New Horizons? But is this part of their charter? I would certainly call the office of Representative Jim Costa if they ask me for this.
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#83
by
Blackstar
on 25 Dec, 2021 12:33
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When I started this thread 3 years ago I expected the report to be published in 2019, hence the 2019 in the title. I would guess we would need to change the thread title
Didn't they release an earlier version in 2019? I know I heard a briefing on that in 2019.
They only needed to get this out before the heliophysics decadal survey started. The preliminary work on that decadal survey is just starting now (my coworkers are involved in setting it up). So even if it's late, it's still in time.
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#84
by
Starbeam
on 26 Dec, 2021 12:21
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Link to thread about using Starship to deliver the Interstellar Probe ...
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#85
by
Kaputnik
on 26 Dec, 2021 13:58
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Were solar sails or SEP also considered for this mission? What would the trades look like there?
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#86
by
Orionwillstay
on 26 Dec, 2021 14:05
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Happy holidays everyone!!
I haven't read the whole of the Mission Concept Report yet, but from what I've covered so far, the biggest surprise to me is that it turns out that Solar Oberth Maneuver does not provide much advantage in reducing mission time to the intended near interstellar distance compared with the "good old" Jupiter flyby. Even worse, SOM adds so much complexity to the detriment of the mission as a whole.
If more speed can be added to the probe so that it will reach the solar gravitational lens in ~50 to 60 years, I wonder if it will become more politically palatable to green-light the mission?
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#87
by
Mariusuiram
on 27 Dec, 2021 19:13
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I hope groundbreaking discoveries in the outer planets could trigger increased funding priority for high C3 propulsion concepts. If Europa Clipper or others create groundbreaking science or if we basically establish that our best chance of discovering life is on the gas giant moons, I could see increased political will for researching improvements. Imagine trying to achieve a program like on Mars with 7-10 year travel times if the goal is to build off earlier missions you'd be working on multi-generational timelines pretty quickly.
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#88
by
Blackstar
on 27 Dec, 2021 19:47
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I hope groundbreaking discoveries in the outer planets could trigger increased funding priority for high C3 propulsion concepts. If Europa Clipper or others create groundbreaking science or if we basically establish that our best chance of discovering life is on the gas giant moons, I could see increased political will for researching improvements. Imagine trying to achieve a program like on Mars with 7-10 year travel times if the goal is to build off earlier missions you'd be working on multi-generational timelines pretty quickly.
One of the problems is that there are no conceivable technologies that can dramatically improve C3 that could both: a) be available in the relatively near-term, and b) be reasonably affordable. Going to the outer solar system puts you way out on the very tiny edge of the rocket equation where things are really hard to change.
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#89
by
LouScheffer
on 28 Dec, 2021 00:47
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In the 34 years between Pioneer 10 and New Horizons, there has not been an appreciable increase in solar system exit velocity capability [...] When you're right out at the pointy end of the rocket equation, big changes in mass to orbit do not offer big increases in achievable velocity. [...] "Fast new ship overtakes old slow ship" is great for sci-fi plots, but frustratingly lacking in actual rocketry.
Going to the outer solar system puts you way out on the very tiny edge of the rocket equation where things are really hard to change.
I completely agree with the sentiment that greater launch mass is not going to help much. Looking at v ~ log(launch mass/ payload mass), we've already reached the point of diminishing returns. This will be true of any solution with any version of any rocket.
The conclusion, I think, is don't use conventional rockets. Exploring the interstellar medium is the poster child for technologies that don't bring their reaction mass/power supply along with them. There are lots of ideas for this, though none are near-term or cheap. Examples are solar sails pushed by multi-GW lasers, or high acceleration mass drivers (10,000G for 20 km gives about 13 au/yr). The technologies needed for implementation of these ideas is advancing, though it's not being driven by the launch industry. Lots of folks are working on graphene, which would be great for high-acceleration sails. SpinLaunch is working on payloads that can withstand 10,000G accelerations. Fusion and particle accelerators are working on high strength, fast-switching magnets. The military is looking at high power lasers, and so on.
So I agree with Ed that the last 35 years have yielded little improvement, even upcoming huge conventional rockets only offer incremental gains, and "Fast new ship overtakes old slow ship" has not come to pass. But I think this will not hold over the next 5-6 decades. And if you are proposing a 60 year mission, waiting another 30 years for a technology twice as fast is a wash, and anything faster an improvement. So my personal feeling is that now is not the right time to launch such a long duration mission. We should re-visit this in 30 years.
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#90
by
Mariusuiram
on 28 Dec, 2021 04:27
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I hope groundbreaking discoveries in the outer planets could trigger increased funding priority for high C3 propulsion concepts. If Europa Clipper or others create groundbreaking science or if we basically establish that our best chance of discovering life is on the gas giant moons, I could see increased political will for researching improvements. Imagine trying to achieve a program like on Mars with 7-10 year travel times if the goal is to build off earlier missions you'd be working on multi-generational timelines pretty quickly.
One of the problems is that there are no conceivable technologies that can dramatically improve C3 that could both: a) be available in the relatively near-term, and b) be reasonably affordable. Going to the outer solar system puts you way out on the very tiny edge of the rocket equation where things are really hard to change.
I guess not an unexpected answer. And to be fair we are still across a few different scales. Most of our concerns with say time to the Ice Giants are solved if we could get to ~300 C3 on a reasonable budget.
https://www.hou.usra.edu/meetings/helio2050/pdf/4057.pdfI found this white paper after a quick search which seems to actually be a spin-off of the Interstellar Probe study generalizing the performance of the SLS Block 2 + Centaur + Star 48 concept. To risk derailing the conversation, but it also seems like cost is a factor here.
Curious if there are any other comparisons of interplanetary propulsion options non-chemical concepts? I found some papers from the early 2000's (maybe that was the time referenced when more were looking at this), but nothing more recent.
If the current optimistic timeline is 15 years from launch to start of mission, it would seem a 5-10 year R&D period would be justified. Again if it had further relevance for outer planet missions most likely.
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#91
by
InterestedEngineer
on 06 Jan, 2022 20:11
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And once again, a science thread becomes a "this can be solved with a Starship" thread.
The science section on NSF is increasingly pointless.
No worries, we in Starship land got you.
TL;DR - refueling Starship in HEEO gives you 200-300 C3 before even a kicker stage, and we're going to beat this to death here:
https://forum.nasaspaceflight.com/index.php?topic=55550.0
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#92
by
su27k
on 07 Jan, 2022 03:17
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LOL "you can't talk about LV here, this is the science section"... meanwhile in the AGU21 press roundtable video above, some guy tried twice to ask if Arianespace can launch this mission. The first time PI tactfully redirected conversation towards European contribution to instruments, but the guy is not satisfied and asked again, and PI is like "Dude if you don't have a super heavy you might as well forget about it".
So yeah, it's not just us internet randos who care about which LV to use for this mission.
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#93
by
deadman1204
on 07 Jan, 2022 21:19
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LOL "you can't talk about LV here, this is the science section"... meanwhile in the AGU21 press roundtable video above, some guy tried twice to ask if Arianespace can launch this mission. The first time PI tactfully redirected conversation towards European contribution to instruments, but the guy is not satisfied and asked again, and PI is like "Dude if you don't have a super heavy you might as well forget about it".
So yeah, it's not just us internet randos who care about which LV to use for this mission.
Blackstars point more is that this thread is SUPPOSED to be about the mission. If people want talk about starship solving all the worlds ills, there are many other threads for that. This isn't that one.
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#94
by
su27k
on 08 Jan, 2022 07:32
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Blackstars point more is that this thread is SUPPOSED to be about the mission. If people want talk about starship solving all the worlds ills, there are many other threads for that. This isn't that one.
Launch vehicle IS an integral part of this mission, haven't you figured it out yet? This is not something you can just put on a random EELV, the PI made it very clear, you absolutely need a super heavy launch vehicle to do this. So let's see, how many SHLV do we have on right now? SLS Block 2, Starship, Chinese LM-9, that's it. (PI also mentioned New Glenn but I think he overestimated NG's performance)
Should be obvious this is not launch on LM-9, that just leaves SLS Block 2 and Starship, so tell me again how Starship is not on topic here?
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#95
by
deadman1204
on 10 Jan, 2022 20:19
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Blackstars point more is that this thread is SUPPOSED to be about the mission. If people want talk about starship solving all the worlds ills, there are many other threads for that. This isn't that one.
Launch vehicle IS an integral part of this mission, haven't you figured it out yet? This is not something you can just put on a random EELV, the PI made it very clear, you absolutely need a super heavy launch vehicle to do this. So let's see, how many SHLV do we have on right now? SLS Block 2, Starship, Chinese LM-9, that's it. (PI also mentioned New Glenn but I think he overestimated NG's performance)
Should be obvious this is not launch on LM-9, that just leaves SLS Block 2 and Starship, so tell me again how Starship is not on topic here?
Yes launch matters, but only insomuch as there is a mission to launch. This is the MISSION thread.
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#96
by
vjkane
on 11 Jan, 2022 00:50
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Launch vehicle IS an integral part of this mission, haven't you figured it out yet?
Yes launch matters, but only insomuch as there is a mission to launch. This is the MISSION thread.
IF this mission is prioritized by the upcoming Heliophysics Decadal Survey, and IF it is funded by Congress, then about 2030 discussions of launch vehicles become relevant. Will enjoy the chats in about 8 years.
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#97
by
su27k
on 12 Jan, 2022 01:43
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Launch vehicle IS an integral part of this mission, haven't you figured it out yet?
Yes launch matters, but only insomuch as there is a mission to launch. This is the MISSION thread.
IF this mission is prioritized by the upcoming Heliophysics Decadal Survey, and IF it is funded by Congress, then about 2030 discussions of launch vehicles become relevant. Will enjoy the chats in about 8 years.
Ok, so you think the mission team should not discuss LV until 2030? They'll just develop this mission without giving thought to whether it can be launched at all? You do realize none of the LVs in NLSII contract as of right now can even launch this mission right?
Fortunately the mission team put more thought into this, as stated in the video above, they have been discussing SLS with MSFC since 2018. So no, discussion of LVs won't be put off to 2030, it is already relevant, it's even written into their report:
Members of the Interstellar Probe study team began working with members of the SLS team after an informal, chance meeting at the 68th International Astronautical Congress (IAC) in Adelaide, Australia, in late September 2017. Multiple technical exchanges led to a comprehensive set of staging curves (injected mass versus C3) in December 2019, which have been used in the Interstellar Probe trade-space study (Stough et al., 2019).
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#98
by
vjkane
on 12 Jan, 2022 23:46
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Ok, so you think the mission team should not discuss LV until 2030? They'll just develop this mission without giving thought to whether it can be launched at all? You do realize none of the LVs in NLSII contract as of right now can even launch this mission right?
The study team (there isn't an approved mission yet, so no mission team) did appropriately look at launch options. When/if there's an approved mission (for a 2036 launch, that would be around 2030) the mission team will evaluate the launchers that will then be available.
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#99
by
LouScheffer
on 13 Jan, 2022 02:23
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Going to the outer solar system puts you way out on the very tiny edge of the rocket equation where things are really hard to change.
Some thought experiments to show how little even a huge change in launch mass changes the result:
Assume you start in Earth orbit, and take full advantage of Earth's orbit around the sun and the rocket's orbit around the Earth. Next, assume a hydrogen/oxygen rocket with ISP = 460. Assume the 860 kg probe from the report.
If you need 5 AU/year, something Centaur-ish will do. 50K kg launch mass, 2500 kg dry mass. This is already at the practical limit of stage performance.
If you need 10 AU/year, you need a stage with half the mass of the Saturn V, but no more dry mass than Centaur. Maybe tanks with flawless graphene skins, assembled in space, or some other wild technology. Definitely beyond the state of the art.
If you need 15 AU/year, give up. You'd need a massless stage with 10x the fuel of the Saturn V.
Staging does not help these number, as staging profits from getting rid of dead weight as soon as possible. These designs have no dead weight.
These limitations apply to any design that uses chemical combustion for energy and carries its own fuel. For thousand AU missions within a human lifetime, we need designs where supplies (power, mass, or both) are sent to the ship. It's the only way around the rocket equation.
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#100
by
Robotbeat
on 13 Jan, 2022 04:20
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That’s not really true. You can use Oberth burns at Jupiter or the Sun to get to 15AU/year with chemical propulsion.
Staging helps by reducing dry mass. You can include the effect of arbitrary number of staging by just assuming the empty stage is massless but reducing the Isp (or exhaust velocity if you will) by the dry mass to wet mass ratio of a stage. So if you had 100 stages for a rocket with 500s or 5km/s exhaust velocity and a dry to wet mass ratio of 0.05, then you treat it as 475s Isp, etc. with lower number of stages, it’s worse than that, but it’s a good limit.
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#101
by
InterestedEngineer
on 14 Jan, 2022 03:25
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Going to the outer solar system puts you way out on the very tiny edge of the rocket equation where things are really hard to change.
Some thought experiments to show how little even a huge change in launch mass changes the result:
Assume you start in Earth orbit, and take full advantage of Earth's orbit around the sun and the rocket's orbit around the Earth. Next, assume a hydrogen/oxygen rocket with ISP = 460. Assume the 860 kg probe from the report.
If you need 5 AU/year, something Centaur-ish will do. 50K kg launch mass, 2500 kg dry mass. This is already at the practical limit of stage performance.
If you need 10 AU/year, you need a stage with half the mass of the Saturn V, but no more dry mass than Centaur. Maybe tanks with flawless graphene skins, assembled in space, or some other wild technology. Definitely beyond the state of the art.
If you need 15 AU/year, give up. You'd need a massless stage with 10x the fuel of the Saturn V.
Staging does not help these number, as staging profits from getting rid of dead weight as soon as possible. These designs have no dead weight.
These limitations apply to any design that uses chemical combustion for energy and carries its own fuel. For thousand AU missions within a human lifetime, we need designs where supplies (power, mass, or both) are sent to the ship. It's the only way around the rocket equation.
You are only correct if you are thinking old fashioned staging where the fuel you have is what you lift off with. That's so 20th century. Err, rather, the Air Force completely changed air power with refueling, so the concept isn't new.
Refueling, especially with a HEEO refuel, changes everything. You can get a 5 ton payload going to > 100km/sec after Jupiter with old fashioned multiple Oberth burns and gravity assists. Turns the JHUAPL mission into a 5 year mission with far more payload mass for the probe. For about $150M in launch costs.
All sorts of gory details in this thread, which is where you should take any replies, since this thread is the thread to handle "how Starship can do extra-solar missions"
https://forum.nasaspaceflight.com/index.php?topic=55550.0
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#102
by
AegeanBlue
on 17 Jan, 2022 05:12
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The random dude in the AGU press conference is far from random, it is Leo Enright (sp?) from Irish Television, which I assume is RTE or their equivalent of PBS. If you watch enough NASA science press conferences about planetary science you will hear him, he regularly participates. Since Ireland is part of the Ariane consortium I would guess, since I have never met the guy, that he is trying to understand if a new megaproject and the jobs it entails is coming for the European space sector.
Now Scientific American has an article on the mission which contains more information than the AGU press conference. It also talks about the Chinese Interstellar mission, also in the proposed stage, called Interstellar Express. Now per that article, which I wish I could link but I read it a few weeks ago, the main instrument that will give the JHUAPL probe a major advantage over Voyager is the Electric Neutral Atoms imager. Which gets for me the question, did ENA imagers exist back in 1977?
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#103
by
AegeanBlue
on 20 Apr, 2022 22:09
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#104
by
Blackstar
on 02 Jun, 2022 17:16
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#105
by
vjkane
on 03 Jun, 2022 00:18
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#106
by
Redclaws
on 03 Jun, 2022 00:35
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#107
by
Blackstar
on 22 Apr, 2023 17:14
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#108
by
Robotbeat
on 22 Apr, 2023 17:33
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That’s awesome.
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#109
by
deadman1204
on 23 Apr, 2023 19:17
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This would be great.
Doubly so if they say they're doing it because the US is to scared too
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#110
by
Don2
on 25 Apr, 2023 19:11
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In the graphic from China, the folded umbrella on a boom looks like a nuclear reactor.
https://en.wikipedia.org/wiki/SNAP-10ALooks like the Chinese are developing a nuclear-electric propulsion system. An interstellar probe would be a good way to demonstrate it.
Developing a pair of nuclear powered probes indicates a very well funded program. I wonder why they have decided to go for nuclear reactors rather than RTGs. Maybe they are developing both?
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#111
by
VSECOTSPE
on 26 Apr, 2023 00:43
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The China mission is Interstellar Express or Interstellar Heliosphere Probe and was just a concept study as of January last year. It probably still is.
The plan is a couple, 200kg, RTG-powered spacecraft to the head and tail of the heliosphere. Supposed to launch in 2024 and reach their destinations by 2049 for the PRC’s centennial. How the mission was going to launch in 2024 when it was still a concept study in 2022 makes the schedule highly suspect. They now claim launch delays to 2025 or 2026 due to Covid, which is still a wildly unrealistic timeline. I would not take this mission seriously unless/until it wins funding in a five-year plan or similar, formal CCP announcement/document. Given the stepwise progress of China’s civil space exploration efforts, that presumably won’t happen until after Tianwen-4/Gan De (last notionally scheduled for launch in 2029) or a similar outer planets mission is undertaken first.
Just like everywhere else, China has business executives, program managers, and researchers floating trial balloons, making presentations, and undertaking studies. Doesn’t mean that everything they’re discussing is government approved and budgeted. Just like everywhere else, a lot/most of it will never enter development.
A third, reactor-powered spacecraft to launch in 2030 to the “north” heliopause is also part of the plan. That’s probably the image in the presentation snapshot upthread.
More here:
https://en.m.wikipedia.org/wiki/Interstellar_Expresshttps://www.scientificamerican.com/article/u-s-and-chinese-scientists-propose-bold-new-missions-beyond-the-solar-system/https://spacenews.com/china-to-launch-a-pair-of-spacecraft-towards-the-edge-of-the-solar-system/https://www.planetary.org/articles/china-voyager-like-interstellar-mission
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#112
by
Bob Shaw
on 26 Apr, 2023 00:59
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They should really build SIX spacecraft rather than two and send them off on all six faces of a cube, providing a holistic view of our local environment!
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#113
by
vjkane
on 26 Apr, 2023 18:45
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The China mission is Interstellar Express or Interstellar Heliosphere Probe and was just a concept study as of January last year. It probably still is.
With NASA, ESA, and probably JAXA, there are public steps to a concept going from that to a project. That is less clear (at least for me) with China, where formal decision making is more closed.
Based on my knowledge, China's lunar program and Mars sample return missions seem to be formally approved. I'm not as certain with the asteroid mission. The interstellar mission still seems to be in the concept stage.
Anyone have better knowledge?
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#114
by
Blackstar
on 26 Apr, 2023 20:12
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The China mission is Interstellar Express or Interstellar Heliosphere Probe and was just a concept study as of January last year. It probably still is.
With NASA, ESA, and probably JAXA, there are public steps to a concept going from that to a project. That is less clear (at least for me) with China, where formal decision making is more closed.
Based on my knowledge, China's lunar program and Mars sample return missions seem to be formally approved. I'm not as certain with the asteroid mission. The interstellar mission still seems to be in the concept stage.
Anyone have better knowledge?
I don't have an answer to your question about China. I will provide a bit more information about how the United States works in taking a concept to an officially approved project. (vjkane already knows all this stuff)
For NASA, planetary, astrophysics, Earth science, and heliophysics all have generally similar structures and processes. Smaller mission concepts, generally on the order from $100 million to ~$1 billion, can compete for selection for an approved mission line and don't have to be on a pre-approved list of missions that can compete. They have to justify the science that they will do as worthy of funding. Missions that cost more (depending on the science area, but let's say it is $500 million to $2 billion) have to be on a pre-approved list of acceptable missions. If they're not on that list, they don't have a chance of being selected. The biggest missions, often referred to as flagships or strategic missions, cost $2+ billion, and they have to be endorsed by a science decadal survey. The planetary decadal survey came out in 2022, the astro one in 2021, and so on. If a mission concept is highly prioritized in a decadal survey, then generally it is going to be funded eventually, although being endorsed in the decadal survey is a necessary but not sufficient condition. If a mission concept is not endorsed by a decadal survey, then it is extremely difficult (maybe impossible) for it to get funded.
So bringing this back to the original topic of the Johns Hopkins University Applied Physics Laboratory Interstellar Probe, right now that is simply a mission concept. It is being pitched by its proponents to the currently ongoing heliophysics decadal survey. Maybe it will be highly prioritized by them, maybe not. So that's how it works for NASA.
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#115
by
VSECOTSPE
on 27 Apr, 2023 03:47
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That is less clear (at least for me) with China, where formal decision making is more closed.
AFAIK, decisions on what major space science missions China undertakes next are made through the CCP’s five-year planning process:
https://en.m.wikipedia.org/wiki/Five-year_plans_of_ChinaThese include R&D and space priorities, at least in recent cycles:
https://www.space.com/china-five-year-plan-space-exploration-2022In the arena of space science, there appear to be two tracks within each five-year planning cycle.
One track is through the China National Space Administration (CNSA), which supports a top-down, stepwise, capabilities-driven program in lunar and planetary exploration. The lunar side is the China Lunar Exploration Program (CLEP), also known as the Chang’e (lunar goddess) Program, which has given us Chang’e 1 thru 5. The planetary side is the Planetary Exploration of China (PEC) Program, also known as the Tianwen (questions to heaven) Program, which has given us Tianwen-1 to Mars so far. Although they obviously conduct space science, these CNSA missions are driven more by proving out new spacecraft capabilities (especially in advance of human missions in the case of CLEP) than scientific curiosity. They progress step-wise — orbit then land then sample return, or Mars then asteroids then Jupiter. The process by which these missions are formulated is pretty opaque and seems to reside with the CNSA bureaucracy. But presumably CNSA sends a proposal (or maybe a set of options), probably within certain CCP-provided budget guidelines, to the CCP as part of each five-year planning process, and then there is some back-and-forth or downselect to get to the missions that will be undertaken in the next five-year plan.
https://en.m.wikipedia.org/wiki/Chinese_Lunar_Exploration_Programhttps://en.m.wikipedia.org/wiki/Planetary_Exploration_of_ChinaA second track is through the Chinese Academy of Sciences and is a bottoms-up, curiosity-driven process more similar to the US decadal planning process. A list of candidate missions are drawn up by the Chinese Academy of Sciences (CAS) from university, government research institute, and industry proposals, and then studied under the current five-year plan for development starts in the next five-year plan. For example, Interstellar Express is one of 13 concepts currently under study for starts in the 2025-2030 Plan (which made me highly skeptical of claims about launching Interstellar Express in 2022 or 2024-2025):
https://www.inverse.com/science/china-space-missions-selection-processCAS makes the recommendation on which mission candidates enter development, although I’m sure there are opaque government decisions on funding after that. The upcoming downselect will become “Strategic Priority Program III” for space science. This paper (in Mandarin, I think) reviews Strategic Priority Program I and II:
https://bulletinofcas.researchcommons.org/journal/vol37/iss8/1/“Strategic” implies big missions. I do not know if there is a separate track or process for smaller CAS missions, like NASA’s Discovery/Explorer or suborbital programs. Also unclear to me is how, all other things being equal, CAS decides between missions in disparate disciplines, like astrophysics versus planetary (although I’ve wondered the same about ESA’s selection process).
Lastly, there’s the large but oddball China Space Station Telescope, also known as Xúntiān or “surveying the sky”, which is a Hubble-sized survey scope that is supposed to co-orbit with the Tiangong manned space station. The Tiangong co-orbit would imply CNSA leadership, but Xúntiān seems to be led by the National Astronomical Observatories of CAS, which runs China’s ground telescopes. I’m not sure which track, CAS or CNSA, Xúntiān went through or future major observatories will go through. Just to add to the confusion on major space observatories, the China Aerospace Science and Technology Corporation (CASC) is studying a SIM/TPF clone for exoplanet hunting:
https://spacenews.com/china-to-hunt-for-earth-like-planets-with-formation-flying-telescopes/Based on my knowledge, China's lunar program and Mars sample return missions seem to be formally approved. I'm not as certain with the asteroid mission.
CLEP is funded thru the end of Chang’e 8 operations. Chang’e 6 was was a copy of Chang’e 5, and will launch in 2024. Chang’e 6 also starts China’s well-advertised International Lunar Robotic Station (ILRS), which includes Chang’e 7 and 8 that are supposed to launch in 2026 and 2028, respectively. After that, there is planning and technology work towards a human lunar effort, but mission funding is TBD for the 2026+ planning cycle. There are Long March presentations on how to use their rockets in various human lunar architectures that catch the eye of the Western press every few months, but no missions are approved beyond Chang’e 8.
Tianwen 2, the asteroid mission, was approved in the last five-year plan. It’s under development to be launched in 2025. Tianwen 3, the Mars sample return, and Tianwen 4, the Jupiter mission, are funded for technology work. But mission funding won’t be approved until the 2026+ cycle. The architectures for each are still be up in the air, and Tianwen 3 really couldn’t start until Chang’e 5 (lunar sample return in 2020) and Tianwen 1 (Mars landing in 2021) had proven out, anyway. Although they have notional launch dates of 2028 and 2029, I would guess that the launch dates for Tianwen 3 and 4 will be later when the missions are actually funded.
What’s funded thru what (technology versus mission) in the Chang’e and Tianwen programs can be gleaned from the current five-year CNSA plan:
http://www.cnsa.gov.cn/english/n6465652/n6465653/c6813088/content.htmlI’m an armchair Sinophile at best, so anyone with better knowledge or insights should correct or add to the above.
FWIW...
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#116
by
JulesVerneATV
on 02 Nov, 2023 14:30
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