Several times during the briefing, Stern indicated how having a future mission that orbited Pluto would answer so many outstanding questions the team has. He outlined one potential mission that is in the very earliest stages of study where a spacecraft could be launched on NASA’s upcoming Space Launch System (SLS) and the spacecraft could have an RTG-powered ion engine that would allow a fast-moving spacecraft the ability to slow down and go into orbit (unlike New Horizons). This type of architecture would allow for a flight time of 7.5 years to Pluto, quicker than New Horizons’ nearly 9.5 years.
There would be some serious orbital perturbations from Charon - could a Pluto orbiter manage those?
Aren't Pluto and Charon's rotations tidally locked?Wouldn't a Charon or L -point outpost always just see the same side of Pluto?
Quote from: bkellysky on 10/19/2016 10:27 pmAren't Pluto and Charon's rotations tidally locked?Wouldn't a Charon or L -point outpost always just see the same side of Pluto?Yes, that's true. We'd miss out on the very intriguing far side of Pluto. Ideally, I think that a Pluto orbiter would want to get initially captured into a very wide orbit of Pluto, and slowly spiral inwards, so we can get a closer view of everything in the Pluto system from all sides, flybys of the moons, etc. and then later on in the mission get closer in and check out the far side of Charon and Pluto before going for a close-in orbit of Pluto.
It seems as if a spacecraft could use aerobraking to enter Pluto's orbit.
Its atmospheric density at the surface is about 10^-4 (at the season New Horizon flew by it)
Surface composition and analyzing the interior seem to be implied interest.
Quote from: redliox on 03/06/2017 03:21 amSurface composition and analyzing the interior seem to be implied interest.That's unusual! One difficulty in realising this mission is that there's probably lots of other easier orbital missions that people would prefer.
AlanStern @AlanSternIn Houston today, 35 of us-- and we're planning the NEXT mission to Pluto! #Pluto #NASA #Plutoflyby
Paul Scott Anderson @paulsandersonReplying to @Dales_Starman and 3 othersIn response to a question on Facebook, he says it's an orbiter.
So maybe somebody can chime in here and answer if my assumption is correct:I assume that any orbital mission going to Pluto is going to take longer to reach Pluto than New Horizons did. My reasoning is that New Horizons blasted up to a pretty fast velocity and then zoomed out to Pluto, with no need to slow down. But any orbiter is going to have to slow down, and it is going to have to slow down before it even gets near Pluto, so accelerate, go for a distance, then start slowing down. Instead of a 9-year flight time, it's going to be more, maybe 50% more?Does that sound reasonable?I would also guess that they might want some kind of solar electric propulsion system, with RTG-electric for deceleration and orbital insertion.
Quote from: Blackstar on 04/24/2017 09:00 pmSo maybe somebody can chime in here and answer if my assumption is correct:I assume that any orbital mission going to Pluto is going to take longer to reach Pluto than New Horizons did. My reasoning is that New Horizons blasted up to a pretty fast velocity and then zoomed out to Pluto, with no need to slow down. But any orbiter is going to have to slow down, and it is going to have to slow down before it even gets near Pluto, so accelerate, go for a distance, then start slowing down. Instead of a 9-year flight time, it's going to be more, maybe 50% more?Does that sound reasonable?I would also guess that they might want some kind of solar electric propulsion system, with RTG-electric for deceleration and orbital insertion.Not necesssarily. The brute force approach is to use an enormous rocket (Where would that come from?) and production bi-prop engines to break rather quickly into orbit. That results in an orbiter half the mass of New Horizons. I think it still needs an RTG, which will continue to be hard to come by. But the optimum trajectory might be slower, as you suggest. As far as I know, without an ASRG (?) we don't have the technology for a continuous thrusting NEP mission, which would take longer to get there as you say. It's been a while since reading those papers. Dr Stern has my concept for a Pluto orbiter mission. Perhaps he will include it in the trade studies. It's neither of the above, but is similar in aspects to what you suggested. Any way you cut it, a second mission to Pluto will have to percolate to the top of the priority list, which will take years maybe decades. It will fall again to a new prominent young scientist who will then have the adequate life expectancy to captain what will be a two decade long program.I hope to live to see it. I ❤️ Pluto (Rationality has its limits)
As far as I know, without an ASRG (?) we don't have the technology for a continuous thrusting NEP mission, which would take longer to get there as you say. It's been a while since reading those papers.
Depends if Stern gets the top job at NASA, isn't he considered one of the candidates especially in light of his championing of commercial space or did I imagine that?
Quote from: Star One on 04/24/2017 10:08 pmDepends if Stern gets the top job at NASA, isn't he considered one of the candidates especially in light of his championing of commercial space or did I imagine that?Seems unlikely.
I wonder if some sort of deployable balloon could be used as a parachute to increase the efficiency of aerobraking? Or even a parachute itself? The forces acting on such a device might be qiote extreme if it was being asked to dump a lot of velocity over a brief period.
Why a balloon? It'd be much heavier for the same amount of area = brake power than a parachute
This discussion got a little silly.How thick is Pluto's atmosphere? How thick will it be 30 years from now?
“The next appropriate mission to Pluto is an orbiter, maybe equipped with a lander if we had enough funding to do both,” New Horizons’ principal investigator Alan Stern told Universe Today in March.This week, Stern has shared on social media that the New Horizons’ science team is meeting. But, separately, another group is starting to talk about a possible next mission to Pluto.
A better option might be to use a propulsion system of combined technologies. Stern mentioned a NASA study that looked at using the SLS as the launch vehicle and to boost the spacecraft towards Pluto, but then using an RTG (Radioisotope Thermoelectric Generator) powered ion engine to later brake for an orbital arrival.
“The SLS would boost you to fly out to Pluto,” Stern said, “and it would actually take two years to do the braking with ion propulsion.”Stern said the flight time for such a mission to Pluto would be seven and a half years, two years faster than New Horizons.
If this propulsion system works as planned, it could launch a Pluto orbiter and a lander (or possibly a rover), and provide enough power maintain an orbiter and all its instruments, as well as beam a lot of power to a lander. That would enable the surface vehicle to beam back video to the orbiter because it would have so much power, according to Stephanie Thomas from Princeton Satellite Systems, Inc., who is leading the NIAC study.“Our concept is generally received as, ‘wow, that sounds really cool! When can I get one?’” Thomas told Universe Today. She said her and her team chose a prototype Pluto orbiter and lander mission in their proposal because it’s a great example of what can be done with a fusion rocket.Their fusion system uses a small linear array of solenoid coils, and their fuel of choice is deuterium helium 3, which has very low neutron production.
In terms of the Pluto mission itself, Thomas said there aren’t any particular hurdles on the orbiter itself, but it would involve scaling up a few technologies to take advantage of the very large amount of power available, such as the optical communications.“We could dedicate tens or more kW of power to the communication laser, not 10 watts, [like current missions]” she said. “Another unique feature of our concept is being able to beam a lot of power to a lander. This would enable new classes of planetary science instruments like powerful drills. The technology to do this exists but the specific instruments need to be designed and built. Additional technology that will be needed that is under development in various industries are lightweight space radiators, next-generation superconducting wires, and long-term cryogenic storage for the deuterium fuel.”Thomas said their NIAC research is going well.“We are busy working on higher fidelity models of the engine’s thrust, designing components of the trajectory, and sizing the various subsystems, including the superconducting coils,” she said. “We have completed Phase I and are awaiting NASA’s response to our Phase II proposal. Our current estimates are that a single 1 to 10 MW engine will produce between 5 and 50 N thrust, at about 10,000 sec specific impulse.”
But even if everyone agrees a Pluto orbiter should be done, the earliest possible date for such a mission is sometime between the early 2020s and the early 2030s. But it all depends on the recommendations put forth by the scientific community’s next decadal survey, which will suggest the most top-priority missions for NASA’s Planetary Science Division.These Decadal Surveys are 10-year “roadmaps” that set science priorities and provide guidance on where NASA should send spacecraft and what types of missions they should be. The last Decadal Survey was published in 2011, and that set planetary science priorities through 2022. The next one, for 2023-2034, will likely be published in 2022.The New Horizons mission was the result of the suggestions from the 2003 planetary science Decadal Survey, where scientists said visiting the Pluto system and worlds beyond was a top-priority destination.So, if you’re dreaming of a Pluto orbiter, keep talking about it.
“Going back to Pluto is becoming, in the scientific community, a real growing concern instead of just scattered conversation,” Stern said. And so, a few days ago, he and 34 scientists gathered in Houston, Texas to start mapping out what an orbiter mission would look like. Some of this new team is comprised of New Horizons members and seasoned pros in the field, in addition to scientists at the start of their careers.“You won’t see it presented in the next few months, but I’m sure that by next year you’ll see it in many places,” Stern said. He added that this October, he and his team plan to have a workshop on their new mission concept at the 49th meeting of the Division of Planetary Sciences.
While the plans are still in their infancy, Stern and his team are hopeful that they can get their concept together in time for the next Planetary Science Decadal Survey, a massive report prepared for NASA and Congress by the planetary science community, which helps to set the space agency’s priorities for solar system exploration. The next Decadal Survey will start being compiled around 2020, Stern said.Gathering enough support within the scientific community is critical to convince the space agency such a trip would be worth it. The good news for Stern and his team is that the public already has their back. As soon as he tweeted the news about the potential orbiter, Stern’s mentions erupted with well-wishers.
This sounds very much like a flagship mission. I don't think a Pluto Orbiter (+Lander?) will be given priority over MSR, a Europa Lander or Ice Giant Mission.
While it does sound like an interesting mission, I think a Triton Orbiter, and maybe a flyby of another Rounded TNO (How many are there?) would be a far better use of resources and easier to do.
Quote from: Torten on 04/28/2017 03:30 pmWhile it does sound like an interesting mission, I think a Triton Orbiter, and maybe a flyby of another Rounded TNO (How many are there?) would be a far better use of resources and easier to do.Triton is influenced and changed by Neptune it is not a standalone pristine KBO like Pluto. And why waste your time going onto a further unstudied TNO when with Pluto you've already had the initial flyby data. Plus I really doubt such a mission would garner anywhere near the public/political engagement that a Pluto mission would.
Quote from: Star One on 04/28/2017 05:13 pmQuote from: Torten on 04/28/2017 03:30 pmWhile it does sound like an interesting mission, I think a Triton Orbiter, and maybe a flyby of another Rounded TNO (How many are there?) would be a far better use of resources and easier to do.Triton is influenced and changed by Neptune it is not a standalone pristine KBO like Pluto. And why waste your time going onto a further unstudied TNO when with Pluto you've already had the initial flyby data. Plus I really doubt such a mission would garner anywhere near the public/political engagement that a Pluto mission would.Its debatable how pristine Pluto is. Charon and maybe the other moons likely formed via a major impact that would have melted and solidified Pluto.
Aerocapture and aerobraking at Pluto.
Quote from: TakeOff on 09/27/2017 11:58 amAerocapture and aerobraking at Pluto. Does it say "aerocapture"? The article is unclear on that. I have a hard time believing that it is possible to get to Pluto and land without some kind of propulsive braking.
Quote from: Blackstar on 09/27/2017 02:18 pmQuote from: TakeOff on 09/27/2017 11:58 amAerocapture and aerobraking at Pluto. Does it say "aerocapture"? The article is unclear on that. I have a hard time believing that it is possible to get to Pluto and land without some kind of propulsive braking.No, this is a landed mission that takes advantage of two key facts: Pluto has very low surface gravity and it has a very thin but extended atmosphere. If you employ a very, very large heat shield, you can use very thin upper atmosphere to slow down an entering vehicle with very little heating. There were proposals to have large inflatable re-entry craft that astronauts could use for emergency return to Earth.
Quote from: vjkane on 09/27/2017 03:44 pmQuote from: Blackstar on 09/27/2017 02:18 pmQuote from: TakeOff on 09/27/2017 11:58 amAerocapture and aerobraking at Pluto. Does it say "aerocapture"? The article is unclear on that. I have a hard time believing that it is possible to get to Pluto and land without some kind of propulsive braking.No, this is a landed mission that takes advantage of two key facts: Pluto has very low surface gravity and it has a very thin but extended atmosphere. If you employ a very, very large heat shield, you can use very thin upper atmosphere to slow down an entering vehicle with very little heating. There were proposals to have large inflatable re-entry craft that astronauts could use for emergency return to Earth.Okay, but let's be clear: this is slowing down and landing from ORBIT, not using aerocapture to get into orbit in the first place. The proposal assumes that the spacecraft is already orbiting Pluto, correct?
A grassroots movement seeks to build momentum for a second NASA mission to the outer solar system, a generation after a similar effort helped give rise to the first one.
Nearly three dozen scientists have drafted letters in support of a potential return mission to Pluto or to another destination in the Kuiper Belt, the ring of icy bodies beyond Neptune's orbit, Singer told Space.com.These letters have been sent to NASA planetary science chief Jim Green, as well as to the chairs of several committees that advise the agency, she added."We need the community to realize that people are interested," Singer said. "We need the community to realize that there are important, unmet goals. And we need the community to realize that this should have a spot somewhere in the Decadal Survey."That would be the Planetary Science Decadal Survey, a report published by the National Academy of Sciences that lays out the nation's top exploration priorities for the coming decade."This is the way it normally works," said New Horizons principal investigator Alan Stern, who's also based at SwRI."First it bubbles up in the community and then, when there's enough action, the agency starts to get behind it," Stern, who has been the driving force behind New Horizons since the very beginning, told Space.com. "Then it lets the Decadal Survey sort things out."Stern contributed a letter to the new campaign, and he has voiced support for a dedicated Pluto orbiter. Singer would also be happy if NASA went back to the dwarf planet."Pluto just has so much going on," she said.
"I would say 25 years is the longest I think about," she said, referring to how long it may be before another Kuiper Belt mission gets to its destination. "And I hope it may be more like 15 years."
While an orbiter/probe for Uranus seems the main route, there may be possibilities for a fly-by coupled with a Kuiper object according to another presentation via the OPAG: http://www.lpi.usra.edu/opag/meetings/feb2017/presentations/Zangari.pdfThese slides show the alignments, and the probable trajectories, a flyby mission could undertake during the ~next quarter-century. Jupiter alone could probably fling a probe to most objects, but an alignment with one of the other gas giants enhances the ability to tweak the trajectory...Neptune could send a probe to any of six objects, the largest being Eris itself (so long as you're willing to wait to reach it). Uranus is sparser with only three, Varuna the major one. A route via Saturn would be as rich as Neptune, and includes the 2 next most massive dwarfs, Haumea and Makemake. This raises a large number of possibilities, all of which depend on the would-be-mission's priorities. For instance....If the priority is the Kuiper object, either Saturn or Neptune are your best options because either can give you access to the more prominent bodies; Eris would be awesome to see although it'd probably be a tertiary choice since the next-largest-bodies, including the multi-mooned and uniquely-shaped Haumea, are far more accessible in a quicker time scale.If the priority is Neptune, you get a great chance for fresh science and, thanks to Neptune's position at the edge with less interference from the Sun's gravity well, a wide range to redirect the probe afterwards. Studying Triton against Pluto or the Kuiper belt would be great for comparison. Not as much science as an orbiter naturally, but you get a chance to study both the planet and bodies it affected during its evolution.If the priority is Uranus or Saturn, there isn't quite as much useful science you could do as compared to the first two. The best chance would be to drop off a Saturn probe, using the Kuiper probe as the carrier. Saturn's main gain would be gaining knowledge about its atmosphere and accessing a great selection of dwarfs, whereas Uranus is likewise its atmosphere, structure, and mapping more of its moons.Between this and the study summary from Amy Simon and Mark Hofstadter, I'd definitely cross Uranus off the fly-by list and only reserve that as a Neptune option. It is a bonus learning that missions to both Neptune and Saturn could vastly increase our knowledge of the Kuiper Belt as much as New Horizons; I'd definitely like to see the would-be-carrier of a Saturn probe (like ESA's proposed Hera for instance) have an option to fly-by say Haumea afterwards.
Quote from: Blackstar on 09/27/2017 02:18 pmQuote from: TakeOff on 09/27/2017 11:58 amAerocapture and aerobraking at Pluto. Does it say "aerocapture"? The article is unclear on that. I have a hard time believing that it is possible to get to Pluto and land without some kind of propulsive braking.No, this is a landed mission that takes advantage of two key facts: Pluto has very low surface gravity and it has a very thin but extended atmosphere. If you employ a very, very large heat shield, you can use very thin upper atmosphere to slow down an entering vehicle with very little heating. There were proposals to have large inflatable re-entry craft that astronauts could use for emergency return to Earth.This Pluto proposal would use a large inflated balloon and the friction with the thin but extended atmosphere to slow down enough that a small lander could then finish the landing with landing rockets. Because Pluto's gravity is thin, it could then hop tens or hundreds kilometers away to explore several other locations.Since the only goal of the balloon is to provide a really large surface area, there's no need for complicated guidance and maneuver capability like there is with aerocapture.I believe that the same trick would work with Triton. I don't believe that this approach would work for any other bodies -- the thin atmosphere doesn't extended far enough vertically because the planet's gravity is too high.A couple of questions I would have would be whether or not the small lander could carry enough fuel to boost itself into orbit for a planetary reconnaissance. The public information on the proposal emphasizes that the lander must be small so that the balloon only has to slow a small mass.
Is it possible to aerobrake with a parachute?Matthew
SwRI TEAM MAKES BREAKTHROUGHS STUDYING PLUTO ORBITER MISSIONA Southwest Research Institute team using internal research funds has made several discoveries that expand the range and value of a future Pluto orbiter mission. The breakthroughs define a fuel-saving orbital tour and demonstrate that an orbiter can continue exploration in the Kuiper Belt after surveying Pluto. These and other results from the study will be reported this week at a workshop on future Pluto and Kuiper Belt exploration at the American Astronomical Society’s Division for Planetary Sciences meeting in Knoxville, Tennessee.
But it’s also the move into the Kuiper Belt that has Stern’s attention. It makes a Pluto orbiter of this design a multi-purpose spacecraft and leverages our growing experience with ion propulsion. Says Stern:“This is groundbreaking. Previously, NASA and the planetary science community thought the next step in Kuiper Belt exploration would be to choose between ‘going deep’ in the study of Pluto and its moons or ‘going broad’ by examining smaller Kuiper Belt objects and another dwarf planet for comparison to Pluto. The planetary science community debated which was the right next step. Our studies show you can do both in a single mission: it’s a game changer.”
From the paper, this is a bit of an eye-opener:There is a KBO mission possible for every Earth-Jupiter launch window throughout a Jupiter revolution, thus Pluto and every one of the selected 45 KBOs are accessible via Jupiter gravity assist with a flight time of under 25 years and a C3 [excess launch energy] less than 140 km2/s2. Many, but not all objects can be reached via Saturn flyby, and a smaller list still can be compatible with a visit to an ice giant, though it does not necessarily provide a TOF [time of flight] advantage.Which leads to this:We found that all five of the non-Pluto KBOs studied by McGranaghan et al [23] can be reached by giant planet swingby— (136199) Eris and (90377) Sedna with Neptune, and (50000) Quaoar, (136472) Makemake and (136108) Haumea via Jupiter-Saturn. Fast-rotator (20000) Varuna is reachable after a Uranus encounter.
Quote from: Torten on 04/28/2017 03:30 pmWhile it does sound like an interesting mission, I think a Triton Orbiter, and maybe a flyby of another Rounded TNO (How many are there?) would be a far better use of resources and easier to do.Triton is influenced and changed by Neptune it is not a standalone pristine KBO like Pluto. And why waste your time going onto a further unstudied TNO when with Pluto you've already had the initial flyby data.
Quote from: Star One on 04/28/2017 05:13 pmQuote from: Torten on 04/28/2017 03:30 pmWhile it does sound like an interesting mission, I think a Triton Orbiter, and maybe a flyby of another Rounded TNO (How many are there?) would be a far better use of resources and easier to do.Triton is influenced and changed by Neptune it is not a standalone pristine KBO like Pluto. And why waste your time going onto a further unstudied TNO when with Pluto you've already had the initial flyby data.For that very reason. You study the unstudied. (Not that Triton is actually unstudied.) Plus a Neptune orbiter gives you a whole pantheon of objects to study, some captured, some naturally formed, some possibly naturally formed but thrown into chaos by the capture of Triton. Plus rings. Plus Neptune itself.But amongst the TNO's, my preference would be Haumea. It's may represent a unique snapshot of a dynamic process (collision, merging or something similar), including a ring of debris. It colour suggests recent resurfacing. It's not too far out (unlike Eris, for eg), and there's nice gravitational slingshots available in 6 and 7yrs, giving a reasonable mission time (even without a magic fusion drive.) If is is a collision remnant, it could be partially and unevenly stripped, giving us access to the differentiated layers inside a TNO.Additionally, with Makemake similarly located in the sky, you could build two identical probes for separate launches into the same slingshot, arriving within a couple of years of each other. That should reduce the per-probe cost, while maximising science return. (Makemake is a red TNO, so likely organic rich.) It would also make for a nice burst of public interest, IMO.My concern about the Pluto proposal is that it will actually reduce any chance of funding for an outer solar system mission. Any attempt to suggest any other outer solar system target except a Pluto orbiter will be shouted down by the SwRI faction. And a Pluto orbiter will lose to Europa/Titan or any inner solar system missions.
Quote from: Paul451 on 11/18/2019 09:06 amMy concern about the Pluto proposal is that it will actually reduce any chance of funding for an outer solar system mission. Any attempt to suggest any other outer solar system target except a Pluto orbiter will be shouted down by the SwRI faction. And a Pluto orbiter will lose to Europa/Titan or any inner solar system missions.I don’t see any subjective evidence to support your final paragraph.
My concern about the Pluto proposal is that it will actually reduce any chance of funding for an outer solar system mission. Any attempt to suggest any other outer solar system target except a Pluto orbiter will be shouted down by the SwRI faction. And a Pluto orbiter will lose to Europa/Titan or any inner solar system missions.
Yet there's some debate over what causes these giant slabs of rock to move around in the first place.Amongst the many hypotheses put forward over the centuries, convection currents generated by the planet's hot core have been discussed as an explanation, but it's doubtful whether this effect would produce enough energy.A newly published study looks to the skies for an explanation. Noting that force rather than heat is most commonly used to move large objects, the authors suggest that the interplay of gravitational forces from the Sun, Moon, and Earth could be responsible for the movement of Earth's tectonic plates.Key to the hypothesis is the barycenter – the center of mass of an orbiting system of bodies, in this case that of Earth and the Moon. This is the point around which our Moon actually orbits, and it's not directly in the center of mass of our planet, which we call the geocenter.Instead, the location of the barycenter within Earth changes over the course of the month by as much as 600 kilometers (373 miles) because the Moon's orbit around Earth is elliptical due to our Sun's gravitational pull.
Their comparison between Earth and the other major celestial bodies in the Solar System reveals a potential explanation for why we haven't detected tectonic activity on any of the major moons or rocky planets so far. The one closest to Earth in all the necessary parameters, however, is Pluto."One test would be a detailed examination of the tectonics of Pluto, which is too small and cold to convect, but has a giant moon and a surprisingly young surface," says Hofmeister.