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)
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.
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.