Author Topic: Pluto Orbital Mission  (Read 23598 times)

Offline Star One

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Pluto Orbital Mission
« on: 10/19/2016 05:34 pm »
A few very initial details from Alan Stern of a study into this.

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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.

http://www.universetoday.com/131492/latest-results-new-horizons-clouds-pluto-landslides-charon/

Offline Phillip Clark

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Re: Pluto Orbital Mission
« Reply #1 on: 10/19/2016 05:42 pm »
There would be some serious orbital perturbations from Charon - could a Pluto orbiter manage those?
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Re: Pluto Orbital Mission
« Reply #2 on: 10/19/2016 05:45 pm »
There would be some serious orbital perturbations from Charon - could a Pluto orbiter manage those?

Sure, just orbit around the Pluto-Charon barycenter like Hydra, Nix, Kerberos, and Styx do.
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Offline Star One

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Pluto Orbital Mission
« Reply #3 on: 10/19/2016 05:57 pm »
I wonder how heavy a scientific payload you could get away with using such an orbiter following the proposals Stern is thinking of.
« Last Edit: 10/19/2016 08:12 pm by Star One »

Online Blackstar

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Re: Pluto Orbital Mission
« Reply #4 on: 10/19/2016 07:32 pm »
Back around 2008 or so I was working on a study (the "Launching Science" study that you can find on the internet) and we looked at enabling technologies for a bunch of missions. One of those included solar electric propulsion, and we discussed hooking up an RTG to an electric propulsion system.

Apparently it's not as simple as you might think. For starters, RTGs tend to be heavy, so that goes into the equation for using the EP. But there's also an issue involving power output. Apparently one of the toughest parts of a solar electric propulsion system  is the power controller that turns the electricity from your power source into the ion stream going out the EP. As power increases or decreases it affects that power converter and that's difficult to work out. We asked one of the EP experts if an RTG, which has a very gradual power decline, would be easy to deal with. If I remember correctly, his response was something like "It's not as simple as you'd expect." I don't know why, and I doubt that it is impossible to solve.
« Last Edit: 10/19/2016 07:32 pm by Blackstar »

Offline TakeOff

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Re: Pluto Orbital Mission
« Reply #5 on: 10/19/2016 07:32 pm »
Pluto's atmosphere at the ground (in the season NH was there) is about 100 times thicker than the upper atmosphere's of terrestrial planets where aerobraking has been performed to date. So there's potential for aerobraking.

Offline Phil Stooke

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Re: Pluto Orbital Mission
« Reply #6 on: 10/19/2016 08:06 pm »
"Sure, just orbit around the Pluto-Charon barycenter like Hydra, Nix, Kerberos, and Styx do."

No, you want to be much closer in.  But good orbit design might reduce or counteract the effects of Charon.  Possibly something like a polar orbit, low periapsis, orbit period 0.5 of Charon.

Offline Wolfram66

Re: Pluto Orbital Mission
« Reply #7 on: 10/19/2016 09:17 pm »
Halo orbit around Pluto Charon center of mass would work... like an L1 or L2 orbit used by Discovr et.al.

Offline bkellysky

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Re: Pluto Orbital Mission
« Reply #8 on: 10/19/2016 10:27 pm »
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?

Offline whitelancer64

Re: Pluto Orbital Mission
« Reply #9 on: 10/19/2016 10:47 pm »
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?
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.
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Offline TakeOff

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Re: Pluto Orbital Mission
« Reply #10 on: 10/28/2016 12:07 pm »
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?
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) and aerobraking to date has been done in atmospheric pressures of about 10^-8. Going at low altitude also maximizes the Oberth effect of braking engines. Aerobraking would be used to lower apohadion (Pluto in Greek, you know) which first most economically is put at the limit of Pluto's Hill sphere, while perihadion remains close to the surface. This in-spiraling would be a natural and economic way to enter orbit. And, as you say, scientifically interesting since it covers all distances in the Pluto system.

Offline hop

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Re: Pluto Orbital Mission
« Reply #11 on: 10/28/2016 08:56 pm »
It seems as if a spacecraft could use aerobraking to enter Pluto's orbit.
Unlike, say, a Mars mission, the big dV cost of a Pluto orbiter is slowing down from the arrival, not getting into a specific orbit. To get to Pluto in a reasonable amount of time (like a decade or so...) you need to arrive going > 13 km/s relative to Pluto. The kind of aerobraking you describe wouldn't help. Aerocapture might, but that would be very challenging if it's possible at all.

You might be able to use aerobraking to adjust your orbit within the Pluto system after initial orbit insertion, but that shouldn't be a big deal with conventional methods. Pluto has a puny gravity well (it's ~0.18 Lunar mass), and Charon encounters could probably be used to advantage. You'd certainly want to spend some time close to Charon anyway, either with close encounters or in orbit.

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Its atmospheric density at the surface is about 10^-4 (at the season New Horizon flew by it)
Lack of knowledge of what the atmosphere will be like at arrival would make it a lot harder to design a mission to use it.
« Last Edit: 10/28/2016 08:57 pm by hop »

Offline redliox

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Re: Pluto Orbital Mission
« Reply #12 on: 03/06/2017 03:21 am »
Although no spacecraft specifics mentioned just yet, they have apparently begun discussing what a future Pluto Orbiter would study at the (former?) 9th planet: http://www.lpi.usra.edu/opag/meetings/feb2017/presentations/Buie.pdf

Surface composition and analyzing the interior seem to be implied interest.
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Offline CuddlyRocket

Re: Pluto Orbital Mission
« Reply #13 on: 03/06/2017 06:57 am »
Surface 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.


Offline redliox

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Re: Pluto Orbital Mission
« Reply #14 on: 03/06/2017 07:34 am »
Surface 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.

Pretty much.  However even the scientists discussing the matter acknowledge revisiting Pluto, orbiter or fly-by, is unlikely to happen for decades.  The article I linked specifically mentioned they were discussing the science, not the technology, a Pluto orbiter would hunt.  As far as the technology portion, frankly it just comes down to finding some way to slow a probe down enough to do the job.
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Offline Star One

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Pluto Orbital Mission
« Reply #15 on: 04/24/2017 08:01 pm »
An update on this proposed mission from Alan Stern.

Quote
AlanStern‏ @AlanStern

In Houston today, 35 of us-- and we're planning the NEXT mission to Pluto! #Pluto #NASA #Plutoflyby

https://mobile.twitter.com/AlanStern/status/856553179206627328

It is going to be an orbiter.

Quote
Paul Scott Anderson‏ @paulsanderson

Replying to @Dales_Starman and 3 others
In response to a question on Facebook, he says it's an orbiter.

https://mobile.twitter.com/paulsanderson/status/856587099180457984
« Last Edit: 04/24/2017 08:02 pm by Star One »

Online Blackstar

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Re: Pluto Orbital Mission
« Reply #16 on: 04/24/2017 09:00 pm »
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.

Offline Bob Shaw

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Re: Pluto Orbital Mission
« Reply #17 on: 04/24/2017 09:08 pm »
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.

Offline IanThePineapple

Re: Pluto Orbital Mission
« Reply #18 on: 04/24/2017 09:30 pm »
This could be amazing, I could see them doing a Cassini-style mission where you flyby the moons multiple times while also studying the planet

Offline Comga

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Re: Pluto Orbital Mission
« Reply #19 on: 04/24/2017 09:55 pm »
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.

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)
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Star One

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Re: Pluto Orbital Mission
« Reply #20 on: 04/24/2017 10:08 pm »
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.

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)

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?

Online Blackstar

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Re: Pluto Orbital Mission
« Reply #21 on: 04/25/2017 12:59 am »
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.

Apparently there were some internal studies at NASA ca 2008 or so looking at solar/RTG-electric thrust. The concept was to use solar panels out to around Saturn to power an electric propulsion system, then drop the solar panels and proceed on electric using the RTGs.

I'm going on vague memory here, but from what I remember, a major issue for any electric propulsion system is the power converter that takes the generated power and then turns it into the ion beam that is used for thrust. That converter has to be able to deal with a changing power level because, for instance, as the craft goes farther from the sun the panels generate less electricity and the system has to compensate. It also has to compensate for the switch from solar to RTG.

Certainly an ASRG is better because it produces much better power per kilo of mass. But NASA halted that program and I would guess that restarting it would be quite expensive now.

Online Blackstar

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Re: Pluto Orbital Mission
« Reply #22 on: 04/25/2017 01:00 am »
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?

Seems unlikely.


Offline Comga

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Re: Pluto Orbital Mission
« Reply #23 on: 04/25/2017 01:49 am »
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?

Seems unlikely.

Agreed
If, as NASA Administrator, he could start a Pluto Orbiter mission, he might, but the Administrator can't just start missions.  He wouldn't seek the post.
He appears to have had enough of public service as AA SMD.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Welsh Dragon

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Re: Pluto Orbital Mission
« Reply #24 on: 04/25/2017 07:47 am »
Guessing the only realistic ways of getting an orbiter out there are solar-electric till Jupiter or further, or to use SLS?

Offline Hobbes-22

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Re: Pluto Orbital Mission
« Reply #25 on: 04/25/2017 12:40 pm »
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

Online Blackstar

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Re: Pluto Orbital Mission
« Reply #26 on: 04/25/2017 01:17 pm »
This discussion got a little silly.

How thick is Pluto's atmosphere? How thick will it be 30 years from now?

Offline vjkane

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Re: Pluto Orbital Mission
« Reply #27 on: 04/25/2017 03:06 pm »
Why a balloon? It'd be much heavier for the same amount of area = brake power than a parachute
Probably not enough pressure to fill a parachute.

There have been various proposals to use inflated balloons to do re-entry into Earth's atmosphere.  So far as I know, none were ever implemented.  This Pluto application of the idea is intriguing, but there's a number of technical issues that need to be considered.  Hence the study.  I believe the final reports from these studies are posted, so in a couple of years we can see what they found.

One issue is taking the technology readiness to flight level -- how do you demonstrate this?  Probably only Triton's atmosphere has the same extended low density characteristics.  For comparison, aerocapture has been ready to fly except for that pesky demonstration for many years.

Offline Comga

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Re: Pluto Orbital Mission
« Reply #28 on: 04/25/2017 07:05 pm »
This discussion got a little silly.

How thick is Pluto's atmosphere? How thick will it be 30 years from now?

10 microbar now, and as you alluded to, we have no idea what it would be in three or more decades.
While we could probably calculate the required parachute area from that and the gravity level, we should listed to Blackstar and keep to technologies that could be part of a professional proposal.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Bob Shaw

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Re: Pluto Orbital Mission
« Reply #29 on: 04/25/2017 07:51 pm »
The interesting thing about any consideration of atmospheric deceleration is that, although very thin, the atmosphere of Pluto should (at times) extend a really long way from the planet - at altitude, it would be denser than our own atmosphere at similar altitudes. Unlike Mars, however, where aerocapture is an established technique, the atmospheric density at Pluto seems to be wildly variable. Perhaps my enquiry is a solution in search of a problem!
« Last Edit: 04/25/2017 07:52 pm by Bob Shaw »

Offline Star One

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Re: Pluto Orbital Mission
« Reply #30 on: 04/26/2017 05:16 pm »
According to this article depending on funding the orbiter may include a lander. Some interesting quotage about various proposals for such a mission in the article.

Quote
“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.

Quote
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.

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“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.

Quote
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.

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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.”

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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.

https://www.universetoday.com/135219/next-pluto-mission-orbiter-lander/

Offline Star One

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Pluto Orbital Mission
« Reply #31 on: 04/26/2017 07:07 pm »
Interview with Alan Stern about the proposed follow up Pluto mission.

Hope they can get a proposal into the Decadal survey as Pluto is by default the most studied Kuiper Belt Object.

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“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.

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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.

http://gizmodo.com/scientists-are-already-planning-the-next-mission-to-plu-1794664742
« Last Edit: 04/26/2017 07:17 pm by Star One »

Offline Quagga

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Re: Pluto Orbital Mission
« Reply #32 on: 04/27/2017 08:21 am »
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.

Offline Star One

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Pluto Orbital Mission
« Reply #33 on: 04/27/2017 08:44 am »
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.

Especially if they go down a radical path like the NIAC proposal. If it works it would really make such a mission worth it due to the speed and payload capacity, but of course this will all take time if and when it works out in the lab.
« Last Edit: 04/27/2017 08:46 am by Star One »

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Re: Pluto Orbital Mission
« Reply #34 on: 04/28/2017 03:30 pm »
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.

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Re: Pluto Orbital Mission
« Reply #35 on: 04/28/2017 05:13 pm »
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.

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.

Offline K-P

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Re: Pluto Orbital Mission
« Reply #36 on: 04/28/2017 05:27 pm »
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.

Well, if Planet Nine really does exist, then all this talk about choosing between Triton vs. Pluto vs. same sized TNOs becomes less relevant? At least I hope P9 would become the primary target that moment. (yes yes, a 50+ year mission yes yes...)

And if P9 does not exist, then I would love to see flybys of Eris and especially Haumea much much more than another Pluto mission (even orbital). I'm a sucker for "initial reconnaissance".

But that's just me.

Offline notsorandom

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Re: Pluto Orbital Mission
« Reply #37 on: 05/01/2017 01:54 pm »
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.

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.

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Re: Pluto Orbital Mission
« Reply #38 on: 05/01/2017 01:57 pm »
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.

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.

But isn't constantly being influenced by a gas giant.

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Re: Pluto Orbital Mission
« Reply #39 on: 05/10/2017 02:22 pm »
New space.com article on proposed orbital mission:

http://www.space.com/36697-pluto-orbiter-mission-after-new-horizons.html

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Re: Pluto Orbital Mission
« Reply #40 on: 09/27/2017 09:05 am »
'Hopping Around' on Pluto? Exciting Lander Mission Concept Presented at NASA Symposium

http://www.americaspace.com/2017/09/26/hopping-around-on-pluto-exciting-lander-mission-concept-presented-at-nasa-symposium/

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Re: Pluto Orbital Mission
« Reply #41 on: 09/27/2017 11:58 am »
Aerocapture and aerobraking at Pluto. Wow, I'd be damned! At 1/10 000 of Earth sea level atmospheric pressure on Pluto's surface. Still, aerobraking and aerocapture has not really been used, has it? Aerobraking has been tried out several times but has not been a critical part of a mission AFAIK. It looks promising for missions to the 10 known atmospheric bodies in the Solar System and their hundreds of moons. If Pluto has an "atmosphere" useful for aerobraking, then maybe Eris does too.

Is it sure that Pluto's atmosphere is useful for entering orbit? It is a NIAC award so I don't know whether it is a given or the thing to be investigated.

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Re: Pluto Orbital Mission
« Reply #42 on: 09/27/2017 02:18 pm »
Aerocapture 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.

Offline vjkane

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Re: Pluto Orbital Mission
« Reply #43 on: 09/27/2017 03:44 pm »
Aerocapture 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.

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Re: Pluto Orbital Mission
« Reply #44 on: 09/27/2017 03:58 pm »
Aerocapture 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?

Offline vjkane

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Re: Pluto Orbital Mission
« Reply #45 on: 09/27/2017 04:16 pm »
Aerocapture 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?
No, the large surface area of the balloon plus thin extended atmosphere allows no propulsive* slow down from interplanetary transfer speeds.  No orbiting, no aerocapture.  This is a very clever idea that makes use of past work on very, very large re-entry shields.  Make your shield large enough relative to mass, and the heating is very gentle.  With this approach, you can travel to Pluto at New Horizon speeds without carrying all the fuel needed to decelerate to enter orbit or do a direct landing.  I think this is a genius idea, although we will have to see if all those annoying engineering details work out. 

Here's a link to the press release https://www.eurekalert.org/pub_releases/2017-09/gac-gac092117.php

*After deceleration, the final landing would be done using rockets, but they can probably be pretty low power.  Not much gravity, which enables later substantial hops.

Offline Star One

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Pluto Orbital Mission
« Reply #46 on: 10/27/2017 09:55 pm »
Return to Pluto? Scientists Push for New Mission to Outer Solar System

Quote
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.

Quote
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.

Quote
"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."

https://www.space.com/38589-new-pluto-mission-letter-writing-campaign.html
« Last Edit: 10/27/2017 09:55 pm by Star One »

Offline redliox

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Re: Pluto Orbital Mission
« Reply #47 on: 10/30/2017 10:11 am »
Since revisiting the Kuiper Belt, in addition to Pluto, is a topic my talk in the Ice Giant thread might be relevant plus a pdf on Outer Planet/Kuiper Belt mission possibilities:

https://www.lpi.usra.edu/opag/meetings/feb2017/presentations/Zangari.pdf

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.pdf

These 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.

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Offline matthewkantar

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Re: Pluto Orbital Mission
« Reply #48 on: 10/30/2017 03:27 pm »
Is it possible to aerobrake with a parachute?

Matthew

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Re: Pluto Orbital Mission
« Reply #49 on: 10/31/2017 08:04 am »
Aerocapture 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.

I wonder whether you could use this technique to aerobrake at a comet. The density of the coma is much lower than even the atmosphere of Pluto, but it's also much deeper.

Obviously this would be useful for missions to the comet itself, but if you could find a comet travelling in roughly the right direction, you could hitch a ride and use the comet to provide much of the velocity needed to reach the outer solar system.
 

Offline WBailey

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Re: Pluto Orbital Mission
« Reply #50 on: 10/31/2017 09:42 pm »
Is it possible to aerobrake with a parachute?

Matthew

How about a toroidal ballute?

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Re: Pluto Orbital Mission
« Reply #51 on: 10/24/2018 09:11 pm »
More on this, it appears they have worked out a way to use Charon to slingshot a Pluto orbiter around the system and eventually out into the Kuiper Belt for an extended mission to other dwarf planets, essentially getting a two-for-one.

https://twitter.com/NewHorizons2015/status/1055197087296643076

https://www.swri.org/press-release/swri-pluto-orbiter-kuiper-belt-charon-gravity-assist?utm_source=SA-Local&utm_medium=Distribution&utm_campaign=Pluto-Orbiter-PR&fbclid=IwAR17PoHnAPR-7K4bniOAzn9QeedNJV13icd57JIzsU1sHlxkXxB-cyodukY
Quote
SwRI TEAM MAKES BREAKTHROUGHS STUDYING PLUTO ORBITER MISSION

A 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.

« Last Edit: 10/24/2018 09:15 pm by Alpha_Centauri »

Offline Star One

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Pluto Orbital Mission
« Reply #52 on: 10/25/2018 08:18 pm »
Game-Changer: A Pluto Orbiter and Beyond

Quote
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.”

Quote
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.
« Last Edit: 10/25/2018 08:24 pm by Star One »

Offline redliox

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Re: Pluto Orbital Mission
« Reply #53 on: 10/26/2018 03:59 am »
Not surprised they realized Charon could be useful for a gravity assist; in some Uranus orbiter studies they likewise concluded even Uranus' relatively puny moons could be relatively as useful as the Galileans/Titan despite being planetary lightweights.  Good to calculate ahead of time, although getting into orbit around Pluto is the far greater challenge I'd like to hear a solution to.
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Offline Star One

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Re: Pluto Orbital Mission
« Reply #54 on: 11/05/2019 03:12 pm »
SwRI TO PLAN PLUTO ORBITER MISSION

Oct. 30, 2019 — NASA has funded Southwest Research Institute to study the important attributes, feasibility and cost of a possible future Pluto orbiter mission. This study will develop the spacecraft and payload design requirements and make preliminary cost and risk assessments for new technologies.

The study is one of 10 different mission studies that NASA is sponsoring to prepare for the next Planetary Science Decadal Survey. The results of these studies will be delivered to the National Academy Planetary Decadal Study that will begin in 2020.

The SwRI-led New Horizons mission — which flew past Pluto and its system of moons and then Kuiper Belt Object (KBO) 2014 MU69, the farthest, most primordial object visited to date — has returned data that has made a compelling case for a follow-up mission.

“We’re excited to have this opportunity to inform the decadal survey deliberations with this study,” said SwRI’s Dr. Carly Howett, who is leading the effort. “Our mission concept is to send a single spacecraft to orbit Pluto for two Earth years before breaking away to visit at least one KBO and one other KBO dwarf planet.”

Despite all that New Horizons revealed about the Pluto system and KBOs, it could only begin to explore complex Pluto and its five moons. Additionally, the New Horizons spacecraft carried only a limited payload and many aspects of KBO and dwarf planet science require different kinds instrumentation and the kind of global and temporal coverage that only an orbiter can provide. A Pluto orbiter mission will be designed to answer some of the questions New Horizons discoveries have sparked.

“In an SwRI-funded study that preceded this new NASA-funded study, we developed a Pluto system orbital tour, showing the mission was possible with planned capability launch vehicles and existing electric propulsion systems,” said SwRI’s Dr. Alan Stern, principal investigator of the New Horizons mission as well as the SwRI-funded study. “We also showed it is possible to use gravity assists from Pluto’s largest moon, Charon, to escape Pluto orbit and to go back into the Kuiper Belt for the exploration of more KBOs like MU69 and at least once more dwarf planet for comparison to Pluto.”

For more information, visit Planetary Science or contact Deb Schmid, +1 210 522 2254, Communications Department, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510.

https://www.swri.org/press-release/pluto-orbiter-mission-decadal-survey-study

Offline Paul451

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Re: Pluto Orbital Mission
« Reply #55 on: 11/18/2019 09:06 am »
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.
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 it 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.

[edit: is/it]
« Last Edit: 11/18/2019 12:12 pm by Paul451 »

Offline Star One

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Re: Pluto Orbital Mission
« Reply #56 on: 11/18/2019 11:14 am »
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.
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.

I don’t see any subjective evidence to support your final paragraph.

Re: Pluto Orbital Mission
« Reply #57 on: 11/18/2019 10:40 pm »
Regarding aerocapture/aerobraking, I remember that one of the arguments that led to New Horizons' approval for the window it was launched in was that Pluto's atmosphere was beginning to freeze out as Pluto got closer to aphelion (thus, early launch was necessary if any atmospheric studies were to be done).  This many years later, atmosphere condensing to the surface should be even greater and so much the more when a Pluto orbiter would be launched.  Would there be any significant atmosphere left when an orbiter arrived?

Offline Comga

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Re: Pluto Orbital Mission
« Reply #58 on: 11/18/2019 11:26 pm »
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.

I don’t see any subjective evidence to support your final paragraph.

That was completely subjective.
I believe you meant you don’t see any OBJECTIVE evidence there.
And I would agree.
Shouting is not effective mission advocacy works.
If he meant some other method of short cutting debate it should be more explicit.

Note: quoting error due to phone issues
zubenelgenubi: fixed
« Last Edit: 11/19/2019 02:44 am by zubenelgenubi »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Comga

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Re: Pluto Orbital Mission
« Reply #59 on: 11/19/2019 01:23 pm »
That SwRI has found a way to use Charon to modify an orbit around Pluto and even to leave Pluto is not surprising. Pluto and Charon are dual dwarf planets. The barycenter is outside of Pluto. No other destination is so close to balance.

An interesting question is how much they can use Charon’s gravity to reduce the minimum delta-V necessary to effect capture into orbit. (Probably as a function of time of flight.)

The big issue with a “classical” Pluto orbiter is getting enough mass there that it can do the 10+/- km/sec insertion burn with useful spacecraft mass. I’ve heard about a conceptual orbiter smaller than New Horizons that still needed a rocket larger than the Atlas V 551, which is our largest rocket certified to carry RTGs AIUI.  But the rocket equation is so non-linear that any appreciable decrease in the required delta-V can have a major impact on both those requirements.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline ZpaceXploraerM1

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Re: Pluto Orbital Mission
« Reply #60 on: 06/10/2021 05:12 pm »
One idea that might work is using a walking robot instead of a rover, because if Pluto has water ice, and low gravity, roving would become incredibly difficult...

Offline jbenton

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Re: Pluto Orbital Mission
« Reply #61 on: 01/30/2022 02:47 am »
The following is relevant to Pluto, I promise  ;)

This article concerning a recent study on Earth's tectonic activity recently appeared in my recommended feed:

https://www.sciencealert.com/the-pull-of-the-sun-and-moon-could-be-affecting-plate-motion

The study argues that the gravitational influence of the Moon might be partially responsible for the Earth's tectonic plates (in addition to Earth's internal heating):

Quote
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.

I decided to post this in a proposed Pluto orbiting mission thread because the authors recommended new studies of Pluto to test their hypothesis:

Quote
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.

Any such "examination" would need to account for the fact that the Pluto-Charon barycenter is outside of Pluto, of course.

I decided to post in this thread rather than the Persephone thread as this one seems slightly more active and to consider a wider array of mission proposals.

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