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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.
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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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