Author Topic: Pluto Orbital Mission  (Read 4574 times)

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?

Offline 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.

Offline 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.


Online 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

Offline 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.

Online 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.

Quote
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 »

Offline Torten

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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.

Offline Star One

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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.

Online 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.

Offline Star One

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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.

Offline FutureSpaceTourist

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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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