Author Topic: Proposed Europa Missions  (Read 468769 times)

Offline Don2

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Re: Proposed Europa Missions
« Reply #1640 on: 02/24/2018 07:40 PM »
It would be nice to get to Jupiter faster, but the problem I can see is that Clipper will never be a priority for SLS and it may get kicked off the launcher if it gets in the way of the manned missions. The other issue is that the reliability of SLS is questionable given the low flight rate. The current schedule has Clipper flying 2 and a half years after the first SLS, which is too long a gap between flights IMO.

In the end, I think Clipper rides another vehicle.

Offline clongton

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Re: Proposed Europa Missions
« Reply #1641 on: 02/24/2018 09:01 PM »
It would be nice to get to Jupiter faster, but the problem I can see is that Clipper will never be a priority for SLS and it may get kicked off the launcher if it gets in the way of the manned missions. The other issue is that the reliability of SLS is questionable given the low flight rate. The current schedule has Clipper flying 2 and a half years after the first SLS, which is too long a gap between flights IMO.

In the end, I think Clipper rides another vehicle.

The sooner that decision is made the better.
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Offline Star One

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Re: Proposed Europa Missions
« Reply #1642 on: 02/25/2018 08:20 AM »
It would be nice to get to Jupiter faster, but the problem I can see is that Clipper will never be a priority for SLS and it may get kicked off the launcher if it gets in the way of the manned missions. The other issue is that the reliability of SLS is questionable given the low flight rate. The current schedule has Clipper flying 2 and a half years after the first SLS, which is too long a gap between flights IMO.

In the end, I think Clipper rides another vehicle.

The sooner that decision is made the better.

One of the biggest impediments to the program moving forward at the moment is SLS. Once they can move it elsewhere the better.

Offline Jim

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Re: Proposed Europa Missions
« Reply #1643 on: 02/26/2018 01:00 PM »

One wonders how SLS is supposed to be certified by then.

SLS is not subject to certification. Certification is not applicable to NASA managed vehicles.

Offline redliox

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Re: Proposed Europa Missions
« Reply #1644 on: 02/28/2018 04:41 AM »
Fresh updates thanks to the recent OPAG meeting on 'Clipper:
https://www.lpi.usra.edu/opag/meetings/feb2018/presentations/Pappalardo.pdf
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Offline arezn

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Re: Proposed Europa Missions
« Reply #1645 on: 03/08/2018 06:27 AM »
From another topic:

MATTBLACK:
Yes - things would certainly look good for lunar missions, doing 'distributed launch' of the spacecraft and the Earth Departure Stage (EDS). A Falcon 9 could place a 20 ton Lander or Command Module type vehicle into orbit first. A Falcon Heavy places it's upper stage as an EDS into orbit next, where it's only payload is propellant (65-70 tons?) and a docking mechanism. The spacecraft docks with this and the EDS burns for TLI.

Why not use the scheme for Europa Clipper?
Can Atlas 401/F9 and F9H provide direct flight to Jupiter?

Offline redliox

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Re: Proposed Europa Missions
« Reply #1646 on: 03/08/2018 12:51 PM »
From another topic:

MATTBLACK:
Yes - things would certainly look good for lunar missions, doing 'distributed launch' of the spacecraft and the Earth Departure Stage (EDS). A Falcon 9 could place a 20 ton Lander or Command Module type vehicle into orbit first. A Falcon Heavy places it's upper stage as an EDS into orbit next, where it's only payload is propellant (65-70 tons?) and a docking mechanism. The spacecraft docks with this and the EDS burns for TLI.

Why not use the scheme for Europa Clipper?
Can Atlas 401/F9 and F9H provide direct flight to Jupiter?

There's already an answer if you scroll back a few pages.  Otherwise email the Clipper team and directly ask them.
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Offline Star One

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Re: Proposed Europa Missions
« Reply #1647 on: 03/29/2018 03:56 PM »
Twenty days on the surface doesn’t seem all that much for the time and money invested.

Europa lander concept redesigned to lower cost and complexity

Quote
In a presentation at a meeting of the Committee on Astrobiology and Planetary Science of the National Academies March 28, Kevin Hand of the Jet Propulsion Laboratory said that feedback from a mission concept review for the proposed lander last June led to changes in the design to reduce its cost.

“The technology and science were well received. The marching orders that we got out of that review were to see if we could simplify the architecture to reduce complexity and cost,” he said. While there’s been little discussion of the lander’s cost, Hand said there was a “desire” to reduce its cost to below $3 billion.

The concept for the mission presented at that review involved the launch of the lander on a Space Launch System rocket no earlier than late 2025. The spacecraft would enter orbit around Jupiter in 2030 with a landing on Europa to follow no earlier than December 2031. The battery-powered lander would operate on the surface for at least 20 days, relying on a communications relay spacecraft in orbit to return data to Earth.

http://spacenews.com/europa-lander-concept-redesigned-to-lower-cost-and-complexity/

Offline redliox

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Re: Proposed Europa Missions
« Reply #1648 on: 03/29/2018 10:34 PM »
Excellent update Blackstar; obviously depicts how they're trying to improve the antenna.

So is the main part of the redesign to ditch the orbiting relay setup, leaving basically the descent module and the lander?
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Offline redliox

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Re: Proposed Europa Missions
« Reply #1649 on: 03/29/2018 10:52 PM »
Twenty days on the surface doesn’t seem all that much for the time and money invested.

Overall I agree; the more time the better but in that radiation environment good idea to be conservative and it might not be impossible.

Quote
Another factor that enables the change in design, he said, is a shift in the science requirements for the lander. A report by a science definition team last year had included, as one of the mission’s priorities, the ability of the lander’s instruments to directly detect any life that might exist in the moon’s icy surface.

“That’s a very high bar,” Hand said. “That bar runs the risk of setting expectations too high, perhaps, and also potentially cannibalizing some of the other science that the community sees as very valuable.”

Instead, the mission team looked at what the “sweet spot” for science from the lander mission might be. Hand said that looking for biosignatures of past or present life would simplify the science requirements for the mission, including reducing the amount of data needed to be transmitted back to Earth.

This would be the part I'd worry on: reducing the science for such an expensive mission.  Searching for life by sifting samples under a microscope isn't bad, but including 1 or 2 supplemental experiments (the seisometer as one example) should be allowed.  I'd understand if 75% of the payload is devoted to one objective (like biosignatures).
« Last Edit: 03/29/2018 11:05 PM by redliox »
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Online Blackstar

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Re: Proposed Europa Missions
« Reply #1650 on: 03/29/2018 11:10 PM »
So is the main part of the redesign to ditch the orbiting relay setup, leaving basically the descent module and the lander?

The briefing was at one of our meetings that just ended today. The Europa lander is going through a lot of redesign. The big change was to get rid of the orbiter, but they've also changed the science focus a lot. The goal is to both get the cost down and to broaden the mission because the focus on finding life was considered too narrow. There are some interesting animations as well. The lack of data about the surface makes landing really challenging, so one of their goals is to develop a very smart landing system that can choose the best landing site in real time.

Offline Archibald

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Re: Proposed Europa Missions
« Reply #1651 on: 03/30/2018 08:30 AM »
Nice to see possible collaboration between JUICE and Clipper, NASA and ESA. Makes some sense.
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Offline Star One

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Proposed Europa Missions
« Reply #1652 on: 03/30/2018 08:44 AM »
So is the main part of the redesign to ditch the orbiting relay setup, leaving basically the descent module and the lander?

The briefing was at one of our meetings that just ended today. The Europa lander is going through a lot of redesign. The big change was to get rid of the orbiter, but they've also changed the science focus a lot. The goal is to both get the cost down and to broaden the mission because the focus on finding life was considered too narrow. There are some interesting animations as well. The lack of data about the surface makes landing really challenging, so one of their goals is to develop a very smart landing system that can choose the best landing site in real time.

It’s a shame that time & cost no doubt preclude  the inclusion of something like a very simple probe that could have been put on Clipper to be dropped onto the surface to gain data to help with the lander development. But I suspect the cost of sterilisation alone for planetary protection would have made it prohibitively expensive for something like this.
« Last Edit: 03/30/2018 08:46 AM by Star One »

Offline TakeOff

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Re: Proposed Europa Missions
« Reply #1653 on: 03/30/2018 02:22 PM »
Impactors have been crashed into asteroids to create a temporary plume of material from just under the surface. A, plume the composition of which could be identified by spectroscopy. Could this also be done on the largest airless bodies, like Europa, or is the surface gravity too strong? (I suppose collecting orbiting ejecta for sample return is way too acrobatic).
« Last Edit: 03/30/2018 02:23 PM by TakeOff »

Online ncb1397

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Re: Proposed Europa Missions
« Reply #1654 on: 03/30/2018 05:43 PM »
Impactors have been crashed into asteroids to create a temporary plume of material from just under the surface. A, plume the composition of which could be identified by spectroscopy. Could this also be done on the largest airless bodies, like Europa, or is the surface gravity too strong? (I suppose collecting orbiting ejecta for sample return is way too acrobatic).

Europa is about the mass and size of our moon and impactors have been done on the Moon. Feedback goes the other way as well. The same technology for this lander could be used for a human scale lander if scaled.


See:
https://en.wikipedia.org/wiki/LCROSS
« Last Edit: 03/30/2018 05:46 PM by ncb1397 »

Offline Star One

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Re: Proposed Europa Missions
« Reply #1655 on: 05/02/2018 08:04 PM »
https://twitter.com/NASAOIG/status/991738510171426816

Quote
OIG announces an audit to assess NASA’s management of its mission to Europa, a moon of Jupiter.
« Last Edit: 10/16/2018 10:28 PM by gongora »

Offline redliox

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Re: Proposed Europa Missions
« Reply #1656 on: 08/02/2018 10:31 PM »
An agenda has been posted for the next OPAG in September: https://www.lpi.usra.edu/opag/meetings/sep2018/agenda.pdf
There'll be an update regarding 'Clipper alongside a general science update it appears.
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Offline jbenton

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Re: Proposed Europa Missions
« Reply #1657 on: 08/30/2018 10:33 PM »
Hello Everyone, a few weeks ago, I decided to take a few days to read through this thread. The story of how the Europa Clipper probe came together (and is coming together) is quite interesting, and I was hoping since 2013 at least that it would be able to fly at least as early as 2025. Anyways I read through because I felt that when it does, it'd be nice for me to have some more historical perspective. Given that there has been so much discussion about the possibility of flying on SLS - as well as the requirement to fly on SLS - such as these relatively recent posts:

It would be nice to get to Jupiter faster, but the problem I can see is that Clipper will never be a priority for SLS and it may get kicked off the launcher if it gets in the way of the manned missions. The other issue is that the reliability of SLS is questionable given the low flight rate. The current schedule has Clipper flying 2 and a half years after the first SLS, which is too long a gap between flights IMO.

In the end, I think Clipper rides another vehicle.

The sooner that decision is made the better.

One of the biggest impediments to the program moving forward at the moment is SLS. Once they can move it elsewhere the better.

I was a little surprised to see no mention of this development:

https://www.nasaspaceflight.com/2018/05/sls-block-1-revival-plans-getting-mobile-launcher-money/
https://www.nasaspaceflight.com/2018/04/nasas-dual-ml-plan-extra-sls-block-1-missions/

The availability of two mobile launchers (and the ability of the Block I SLS to support this mission, which was in doubt early on) removes the concern that the Europa Clipper may interfere with Crewed exploration missions and vice-versa. However there remains the LV reliability concerns as well as well as the possibility that SLS may be cancelled by 2022-2025

Offline jbenton

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Re: Proposed Europa Missions
« Reply #1658 on: 08/30/2018 10:34 PM »
SLS is the baseline, but it looks like EC is already designed to be launcher-agnostic:

Thanks for the response. In reference to the launcher decision... I imagine that "if" the SLS could cut the transit time in half, that would certainly alter how they architect the systems? Or no?

Absolutely. First of all, if EC does not have to do the Venus flybys, then they can take off the thermal protection. So how long do they keep designing the vehicle with thermal protection and without it? That's two designs, more money, etc.

Also, a much shorter trip time may affect how much they have to test the spacecraft. But that could be a tricky issue. I'll provide a caveat that I'm not an expert on any of that stuff (remember, I'm a policy wonk), but generally a lot of testing is for lifetime. So they test something to see how long it will last. And if they can test it for a shorter lifetime that costs less.

Cost is probably the true issue for flying via SLS.  For the Europa mission (either the orbiter or lander), it would be wonderful to get directly to Jupiter; bad news is it may cost a lot, which coupled with safety was also a reason satellite providers rapidly abandoned the space shuttle.  I'd like to see the flyby-orbiter fly with it, but I wouldn't want to do that with the lander since developing that will be enough of a future expense as is.
I've worked with enough finance people to know that there is a lot of leeway on how costs are accounted for.  NASA will have large fixed costs for maintaining the capability of launching SLS missions.  Then there will be the marginal costs associated with building an individual booster, transporting it, fueling it, launching it, etc.  The key will be whether the science division (I suspect there are some great telescope observatories that SLS could launch in addition to planetary missions) is charged only the marginal cost or a substantial portion of the fixed costs.

I strongly suspect that NASA will design planetary missions so they can also be launched on commercial systems.  SLS may not work.  Political support may dry up (when will Shelby retire?).  There could be a launch failure and the whole system stands down for a couple of years.  Backups are good.
In the case of the Europa multiflyby mission, a key decision will be whether to expand the fuel tanks or not and/or design the spacecraft for the heat of Venus gravity assists.  The former would allow a deep space maneuver that would shorten the flight to 4.7 years with a Delta IV Heavy.  The latter would allow an EVEEGA trajectory and a 7.4 year flight.  How much insurance will NASA buy?

I heard someone say that they're designing it for the thermal effects of a Venus flyby no matter what. I don't know why, but myabe the margins opened up and they figured it is better to just plan for that no matter what.

It makes perfect sense to have a backup plan in the design of the spacecraft itself (to avoid the cost of duplicity of design), but much has changed since 2016, so I must ask: Are they still designing with TPS for the EVEEGA trajectory?

It would seem to make more sense to me remove the TPS from the design and plan on expanding the fuel tanks with the idea of using the Heavy EELV-launched EGA trajectory for the following reasons:

1) The plan is to launch in 2022, 2023, 2024 or 2025; Atlas V 551 will no longer exist during that time frame. The Falcon 9 Full Thrust Block 5 is the only comparable LV that may be available in that time. Though comparable, performance decreases over time, if I'm not mistaken. According to SpaceX' website, The Falcon 9 does 22,800kg to LEO, 8,300 to GTO and 4,020 trans-Martian Injection; whereas the Atlas V 551 - according to ULA Rocket Builder - does 18,856 to LEO, 8,899 to GTO, and 6,109 to Earth Escape (though MSL, launch mass of 3,839kg, used an Atlas V 541 to Mars which RB says isn't needed until 4,943kg - I take it that some extra propellant is required after Earth-escape for a Mars or Jupiter injection-burn, but I don't know how much)
https://www.spacex.com/about/capabilities
https://www.rocketbuilder.com/start/configure

2) In the 2022-2025 there may be as many as four or five affordable American HEELV launchers: Delta-IV Heavy, Falcon Heavy, Vulcan 562, New Glenn and maybe even OmegA Heavy. This seems to be a more reliable back-up plan.

3) 4.7 years is less than 7.4 years. 'nuf said

4) The TPS is all dead weight, if there is no Venus encounter, whereas the extra fuel can be used for mission extensions.

None of my arguments are valid if SLS has insufficient mass-margin to handle the extra fuel on the 2.7 year Jupiter direct route.

Offline jbenton

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Re: Proposed Europa Missions
« Reply #1659 on: 08/30/2018 10:34 PM »
On the other hand, I was not surprised that no one mentioned this. We all knew by then that the Europa Clipper was being designed to investigate any plumes that it may encounter - only now we have more confidence that there will actually be plumes to investigate:

https://www.nasaspaceflight.com/2018/05/nasa-galileo-flew-europa-plumes-excitement-europa-clipper-mission/

I find it interesting that when Galileo visited Europa, they notices strange perturbations in Jupiter's magnetosphere around Europa, but had no way to account for them. Now, after Cassini's one score and three years in the Saturn system, they now know that Enceladus' plumes have a similar effect on Saturn's magnetosphere. So someone on the Galileo team sifted through old data to see if the perturbations would correspond with some of the plume data that Hubble was watching less than five years ago, and sure enough, it did. It's just amazing how these discoveries can come together from such different science missions originally intended to examine such different things. "Expect the unexpected"

Anyways, that's also part of the story of this mission coming together, thought I'd post it (though anyone who has been following this thread in real-time surely already knows about this)