Author Topic: Missions to the Ice Giants Uranus and Neptune  (Read 124163 times)

Online vjkane

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #560 on: 04/21/2017 02:58 PM »
I thought the orbiter options were pretty interesting though.  A 13 year mission to Neptune launching in 2029, and a 12 year mission to Uranus launching in 2031 could see some pretty interesting comparative science being done - probably using the same team/ground resources.
Another interesting option would be to take advantage of the Saturn-Uranus trajectories that end in 2028.  A single spacecraft could deliver probes to both Saturn and Uranus and orbit the latter.  Unfortunately, to take advantage of this alignment, NASA would need to start pursuing the mission now.  I expect that the decision on which if any Uranus or Neptune missions to pursue will come from the  next Decadal Survey in 2021/2. 

A mission to Uranus or Neptune will be in competition with at least a Europa lander and a Mars sample return.

Offline redliox

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #561 on: 04/21/2017 03:11 PM »
Think this is the main take away: 3 orbiters, a flyby, and 3 atmospheric probes between the 4 options.  What surprises me the most is Uranus is being considered for the flyby in place of Neptune; I can only assume a cheaper cost was the main gain there.
It looks to me like they were bracketing the range of options rather than making some deeper point.

Possibly, but they have to make a decision on what to pursue sooner or later.  I see the merits of each option and no doubt this will be presented to the decadal survey which could be the lynch pin.

Another interesting option would be to take advantage of the Saturn-Uranus trajectories that end in 2028.  A single spacecraft could deliver probes to both Saturn and Uranus and orbit the latter.  Unfortunately, to take advantage of this alignment, NASA would need to start pursuing the mission now.  I expect that the decision on which if any Uranus or Neptune missions to pursue will come from the  next Decadal Survey in 2021/2. 

I'd love to see a Saturn flyby.  I wager, aside from pushing a Saturn probe, the only way to seriously push that option would be a wave of Cassini-nastalsia coupled with an eagerness to revisit Enceladus.
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Offline Blackstar

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« Last Edit: 06/13/2017 04:17 PM by Blackstar »

Offline Blackstar

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #563 on: 06/13/2017 02:56 PM »
« Last Edit: 06/13/2017 04:17 PM by Blackstar »

Offline redliox

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #564 on: 06/14/2017 08:32 PM »
Full report.

http://www.lpi.usra.edu/icegiants/

A genuinely impressive report. 

They apparently still need to review Dual mission options, although there seems to be a consensus with the Dual-stuff that 2 orbiters at one planet isn't as productive as one at each planet.  Fly-bys also appear to be a last-resort, such as a (probeless) Uranus orbiter alongside a Neptune fly-by with probe.  They seem willing to settle for small orbiters at both planets and a single probe if not two probes.  It is good to see, even if more reviews are needed, that some compromises have been agreed upon.

Apparently a 'mega-probe' that has a fully-loaded orbiter and atmospheric probe is estimated at $2.6 billion contrasting with the Uranus fly-by with probe at $1.5 billion, which gives the range for single spacecraft.  Barring a crazy cash infusion to NASA, the $4 billion option for 2 'mega-probes' could be mitigated to sci-fantasy.  A further note says a minimalistic (small orbiters with probes for both) Dual-probe would be $3 billion; while expensive this would be an excellent choice; the key is insuring both orbiters are clone copies.

Aerocapture and optical-coms are acknowledged as being potentially useful but not likely to happen.

In the references, I was pleased to spot one example of a Dual-probe route.  It involved a Mars flyby, SEP thrusting between Earth and Jupiter, and post-Jupiter the Neptune probe would barrel on while the Uranus probe shifts course.
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Online LouScheffer

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #565 on: 06/14/2017 11:05 PM »
Aerocapture and optical-coms are acknowledged as being potentially useful but not likely to happen.
I can't imagine trying aerocapture for the first time with a multi-billion dollar mission after a 15 year flight.  But you could perhaps do a test flight relatively quickly and cheaply.  Send a craft around the moon, and have try to brake into low Earth orbit via aerocapture.  Presumably this is a tougher task than braking at a gas giant, since the gradient of atmospheric density vs height is steeper.  (Venus would be even tougher, but less convenient for testing.)

SpaceX might be able to do this relatively cheaply, with a re-used booster pushing a re-used dragon.  It's not clear to me that this would give enough confidence to then try this at the outer planets, or if you'd need a test flight to Jupiter as a next intermediate technology demonstrator.  (Juno would have been a perfect mission for this - it wanted a low-perijove, high apojove, orbit). 

Offline Blackstar

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #566 on: 06/14/2017 11:31 PM »

SpaceX might be able to do this relatively cheaply, with a re-used booster pushing a re-used dragon. 

And there you go: the inevitable "SpaceX can solve all our problems" post.

Offline Blackstar

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #567 on: 06/14/2017 11:31 PM »
Barring a crazy cash infusion to NASA, the $4 billion option for 2 'mega-probes' could be mitigated to sci-fantasy.

Think: international cooperation.

Offline as58

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #568 on: 06/15/2017 12:14 AM »
Barring a crazy cash infusion to NASA, the $4 billion option for 2 'mega-probes' could be mitigated to sci-fantasy.

Think: international cooperation.

Even with international partners it seems pretty hard, ESA for example is unlikely to have more than M-class worth (~$500M) of money available.

Online LouScheffer

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #569 on: 06/15/2017 01:44 AM »

SpaceX might be able to do this relatively cheaply, with a re-used booster pushing a re-used dragon. 

And there you go: the inevitable "SpaceX can solve all our problems" post.

You can choose to believe this or not, but my only motivation was "What's the cheapest possible way to test aerocapture?"  Clearly Earth is the cheapest place to try this, with by far the best diagnostics, from either a very high apogee orbit, or a powered dive, or a loop around the moon.   Next, unlike aerobraking, you need a craft with a heat shield to try this.  What's the cheapest craft with a heat shield?   Your choice among craft in production (anything else will be lots of bucks) is a SpaceX Dragon or a Soyuz.  SpaceX has used Dragons, presumably cheaper than new ones.  Next, what's the cheapest way to launch it?  Cheap launchers are likely SpaceX, Soyuz, and maybe India's GSLV.  All require integration except Dragon on Falcon or Soyuz on Soyuz.   The Soyuz combination, to my knowledge, does not have enough performance for a high energy re-entry.   The Falcon likely does, if run expendable.  What the cheapest way to get a Falcon?   At this point it's a used one.

So that was my reasoning.  If you can think of any way to do an aerocapture test more cheaply, I'm all ears.

Offline Blackstar

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #570 on: 06/15/2017 01:54 AM »
Barring a crazy cash infusion to NASA, the $4 billion option for 2 'mega-probes' could be mitigated to sci-fantasy.

Think: international cooperation.

Even with international partners it seems pretty hard, ESA for example is unlikely to have more than M-class worth (~$500M) of money available.

I never said it was easy...

One thing you have to understand about these studies (and it is true for the decadal survey as well) is that the cost estimation is based upon the assumption that NASA has to pay the full cost. For instance, on the decadal, we looked at Mars sample return in terms of three missions and the cost assumption was that NASA would have to pay for all of those three missions. But at the time we knew that there was a possibility that a substantial part of the overall program could be paid for by international partners. An obvious choice would be to find an international partner to build the return vehicle, which could cut a significant part off the American responsibility. (It has not worked out like this in actuality, because neither the Obama administration or the current one--or, more precisely, their OMB people--want to commit to sample return, and therefore are not going in search of international partners.)

The way you get international partners and the way you get them to put in a substantial amount of funding, is to commit to your own program and then go approach them at a high level. Having the US vice president speak to ESA representatives about a joint mission is a way to get ESA to pitch in more money. I'm not saying that this is likely, but it is a path to making things happen.

Offline redliox

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #571 on: 06/15/2017 03:59 AM »

SpaceX might be able to do this relatively cheaply, with a re-used booster pushing a re-used dragon. 

And there you go: the inevitable "SpaceX can solve all our problems" post.

I'd politely go so far as to fairly list them as an option, just not the only option.  If available likewise the New Glenn/Armstrong rockets from BO should be considered.  A preferable choice hopefully could be something in the FH range if SLS isn't an option, although the SLS should only be considered if a dual mission or Neptune looks possible.
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Offline redliox

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #572 on: 06/15/2017 04:18 AM »
Barring a crazy cash infusion to NASA, the $4 billion option for 2 'mega-probes' could be mitigated to sci-fantasy.

Think: international cooperation.

Even with international partners it seems pretty hard, ESA for example is unlikely to have more than M-class worth (~$500M) of money available.

I never said it was easy...

One thing you have to understand about these studies (and it is true for the decadal survey as well) is that the cost estimation is based upon the assumption that NASA has to pay the full cost. For instance, on the decadal, we looked at Mars sample return in terms of three missions and the cost assumption was that NASA would have to pay for all of those three missions. But at the time we knew that there was a possibility that a substantial part of the overall program could be paid for by international partners. An obvious choice would be to find an international partner to build the return vehicle, which could cut a significant part off the American responsibility. (It has not worked out like this in actuality, because neither the Obama administration or the current one--or, more precisely, their OMB people--want to commit to sample return, and therefore are not going in search of international partners.)

On the international topic, how useful would you say ESA is?  We've had numerous successes with both Venus & Mars Express, Rosetta (not quite so much Philae), Huygens, and the Trace Gas Orbiter while failures with Beagle 2 and Schiaparelli.  Should NASA/ESA be given specific jobs, specific planets to cover...any thoughts?

I wouldn't think JAXA or many of the others have the capability to handle much beyond Jupiter.
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Offline Blackstar

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #573 on: 06/15/2017 12:01 PM »
On the international topic, how useful would you say ESA is?  We've had numerous successes with both Venus & Mars Express, Rosetta (not quite so much Philae), Huygens, and the Trace Gas Orbiter while failures with Beagle 2 and Schiaparelli.  Should NASA/ESA be given specific jobs, specific planets to cover...any thoughts?

I wouldn't think JAXA or many of the others have the capability to handle much beyond Jupiter.

Working this out (the dual mission) would be somewhat difficult. The reason is that you get some economy from building near-identical spacecraft, and it's not going to be possible to do that and have NASA build one and ESA build the other. So the logical thing to do would be to have NASA (JPL or APL) build two spacecraft and have the international partners contribute dual copies of many instruments. That of course gets thornier because the United States has scientists who want to supply instruments. JAXA could also supply instruments too.

These agreements require "clean interfaces" and bartering goods and services, not money, which means that NASA cannot just build the spacecraft and expect ESA to send over money.

Like I said, not easy. But not impossible.

Offline redliox

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #574 on: 06/15/2017 02:01 PM »
Working this out (the dual mission) would be somewhat difficult. The reason is that you get some economy from building near-identical spacecraft, and it's not going to be possible to do that and have NASA build one and ESA build the other. So the logical thing to do would be to have NASA (JPL or APL) build two spacecraft and have the international partners contribute dual copies of many instruments. That of course gets thornier because the United States has scientists who want to supply instruments. JAXA could also supply instruments too.

These agreements require "clean interfaces" and bartering goods and services, not money, which means that NASA cannot just build the spacecraft and expect ESA to send over money.

Like I said, not easy. But not impossible.

An exception to dual copies of everything would be the few differences in science between Uranus and Neptune.  Uranus was favored to have an extra thermal/infrared device whereas at Neptune ultraviolet was desired.  This naturally is assuming medium-size orbiter payloads, but not large, are possible.

What about the situation of a single craft?  ESA now has Huygens under its belt, and Schiaparelli's loss would be a case of rushed schedules and low budgets like Beagle; entry probes seem a candidate.  However Rosetta and  (soon) JUICE are capable of operating at Jupiter's distance.  That adds another thought - who would supply the radioactive power?
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Offline Blackstar

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #575 on: 06/15/2017 03:25 PM »
What about the situation of a single craft?  ESA now has Huygens under its belt, and Schiaparelli's loss would be a case of rushed schedules and low budgets like Beagle; entry probes seem a candidate.  However Rosetta and  (soon) JUICE are capable of operating at Jupiter's distance.  That adds another thought - who would supply the radioactive power?

ESA also did Rosetta, a large, highly successful mission. ESA is capable of large, sophisticated missions. I think that Schiaparelli is just a single data point and not indicative of larger problems.

NASA would have to provide the Pu-238.

Offline Star One

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #576 on: 06/15/2017 03:43 PM »
Barring a crazy cash infusion to NASA, the $4 billion option for 2 'mega-probes' could be mitigated to sci-fantasy.

Think: international cooperation.

Even with international partners it seems pretty hard, ESA for example is unlikely to have more than M-class worth (~$500M) of money available.

I never said it was easy...

One thing you have to understand about these studies (and it is true for the decadal survey as well) is that the cost estimation is based upon the assumption that NASA has to pay the full cost. For instance, on the decadal, we looked at Mars sample return in terms of three missions and the cost assumption was that NASA would have to pay for all of those three missions. But at the time we knew that there was a possibility that a substantial part of the overall program could be paid for by international partners. An obvious choice would be to find an international partner to build the return vehicle, which could cut a significant part off the American responsibility. (It has not worked out like this in actuality, because neither the Obama administration or the current one--or, more precisely, their OMB people--want to commit to sample return, and therefore are not going in search of international partners.)

The way you get international partners and the way you get them to put in a substantial amount of funding, is to commit to your own program and then go approach them at a high level. Having the US vice president speak to ESA representatives about a joint mission is a way to get ESA to pitch in more money. I'm not saying that this is likely, but it is a path to making things happen.

I'd of thought the chances of European cooperation would be diminished considering the ability of your current commandeer in chief for putting the backs up of European politicians.

Offline Alpha_Centauri

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #577 on: 06/15/2017 04:14 PM »
Those same European politicians not being able to fund their own space programmes adequately probably will have more of an impact tbh.

Offline Blackstar

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #578 on: 06/15/2017 05:40 PM »
I'd of thought the chances of European cooperation would be diminished considering the ability of your current commandeer in chief for putting the backs up of European politicians.

Think longer-term. Presidents come and go.

Perhaps a greater impediment is that NASA has not proven to be a reliable partner on some things, such as canceling ExoMars participation in 2011.

Again, I did not say it would be easy.

Offline Star One

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Re: Missions to the Ice Giants Uranus and Neptune
« Reply #579 on: 06/15/2017 05:45 PM »
I'd of thought the chances of European cooperation would be diminished considering the ability of your current commandeer in chief for putting the backs up of European politicians.

Think longer-term. Presidents come and go.

Perhaps a greater impediment is that NASA has not proven to be a reliable partner on some things, such as canceling ExoMars participation in 2011.

Again, I did not say it would be easy.

That second point is a good one as I've seen it mentioned in pieces since talking about NASA/ESA cooperation.