Author Topic: Proposed Europa Missions  (Read 640935 times)

Offline deltaV

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Re: Proposed Europa Missions
« Reply #760 on: 02/15/2015 08:15 pm »
After some digging, it looks like the SLS missions were using ~85.4km^2/s^2, and both the Atlas V 551 and SLS Block I concepts had spacecraft masses around 5 metric tonnes. I'm going to run some numbers real quick.

Ok, it looks like a refueled Centaur wouldn't cut it--I'm only getting 3600kg to a C3 of ~85-86km^2/s^2. But a refueled DCSS 5m stage looks like it would work--I'm getting ~4800kg to a C3 of 85-86km^2/s^2.

So theoretically, in a magical world where depots exist instead of SLS Block I, you could do the direct to Europa injection using a refueled Delta-IV M+ (5,2) launch, with a lot of mass to spare, you wouldn't need a DIV-H. But you would need a well-stocked propellant depot--<cue vigorous handwaving>.

As I said, it's a political non-starter, but I was morbidly curious from a technical standpoint.

Spreadsheet I used (showing C3 vs payload for a refueled DCSS and a refueled Single-Engine Centaur) attached.

A related question is whether Falcon Heavy could send 4.8 tonnes direct to Europa (C3=86 km^2/s^2). Here are some very hacky results calculated using a simple multi-stage rocket spreadsheet. I calibrated my Falcon dry mass estimates to be consistent with the 53 tonnes to 200 km LEO figure. Without any additional upper stages Falcon Heavy can only send about 2.6 tonnes to Europa. Solid upper stages help, but not enough, e.g. FH plus a Castor 30B can do about 4.0 tonnes. A hypergolic upper stage with ISP 325s, wet mass 14 tonnes, and PMF of 0.94 could send 4.8 tonnes. Unfortunately such an aggressive PMF is unlikely to be cheap if it's even possible; compare to the Briz-M which has wet mass 22.17 tonnes, PMF 0.893, and ISP 326s.

It looks like just about any LOX-hydrocarbon or LOX/LH2 pump-fed upper stage of about 20 tonnes wet mass should be enough to send 4.8+ tonnes to Europa. Unfortunately there are very few stages of that description (most LOX-burning stages are bigger). The only suitable stages that would be demonstrated in time for this Europa mission seem to be ULA's Centaur, DCSS 4m and DCSS 5m RL-10-based stages. By my calculations any of these 3 launched on Falcon Heavy could send 7+ tonnes direct to Europa. I suspect that the cost and risks involved with outfitting a Falcon Heavy pad for hydrogen and integrating a ULA stage on the Falcon Heavy makes this not viable, especially politically. Of course Falcon Heavy could be used as an alternative to Atlas for the Venus flyby route; my conclusion is only that Falcon Heavy is not viable for launching the probe on the faster Venus-less route.

Surprisingly SLS block 1 with ICPS (which is DCSS 5m) can only send around 6 tonnes to C3=86 km/s^2 (e.g. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130013034.pdf), i.e. a bit less than Falcon Heavy despite being a bigger rocket. I think the reason for SLS's poor performance here is ICPS is too small relative to the large burnout mass of the SLS core so a lot of potential performance is wasted on the empty core. If SLS had a more suitable upper stage than ICPS it would do a lot better.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #761 on: 02/16/2015 02:20 pm »
Back in October I had lunch sitting next to a guy from Aerojet who was working on an upper stage for (I think) Falcon Heavy to enable SpaceX to compete for the Solar Probe Plus mission. Dunno if that's gone public anywhere, but it may be mentioned elsewhere on this site. Anyway, they're locked out of a number of missions unless they upgrade their hardware.

One other thing: Falcon Heavy is not using cross-feed. They're not developing it. I was at SpaceX several months ago and asked about cross-feed and was told by one of the people working on the rocket that they are not developing it. It's a potential upgrade if somebody pays for it, but they're not doing the development. So you shouldn't use it in your calculations.

Offline deltaV

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Re: Proposed Europa Missions
« Reply #762 on: 02/16/2015 05:56 pm »
One other thing: Falcon Heavy is not using cross-feed.... So you shouldn't use it in your calculations.

I switched my spreadsheet to turn off cross-feed, re-calibrated it to match the known 45 tonnes to LEO figure for FH without cross feed (http://www.spacex.com/falcon-heavy), and found that Falcon Heavy without crossfeed plus Centaur can send about 6.2 tonnes direct to Europa. So that's still an option even without cross feed.

I'll reply to the rest of your post in the Falcon Heavy discussion thread 3.

Offline Robotbeat

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Re: Proposed Europa Missions
« Reply #763 on: 02/16/2015 07:29 pm »
Back in October I had lunch sitting next to a guy from Aerojet who was working on an upper stage for (I think) Falcon Heavy to enable SpaceX to compete for the Solar Probe Plus mission. Dunno if that's gone public anywhere, but it may be mentioned elsewhere on this site. Anyway, they're locked out of a number of missions unless they upgrade their hardware.
...
Solar Probe Plus is an extremely high delta-v mission, so most likely they were just talking to them about a kick stage or something.

I really doubt this could be generalized to large, lower-energy payloads. It's quite possible for Falcon Heavy to beat Delta IV Heavy and Atlas V 551 to LEO and GTO while still not being quite as powerful to the extremely high delta-v trajectory that solar probe would need.

So if solar probe all you're basing the bolded text on (and it may not be), then I think it's not a justified statement, unless "a number of missions" means 1.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline deltaV

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Re: Proposed Europa Missions
« Reply #764 on: 02/16/2015 07:39 pm »
Robobeat, let's move this discussion to the Falcon Heavy thread. Solar Probe Plus is off-topic here.

Offline baldusi

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Re: Proposed Europa Missions
« Reply #765 on: 02/17/2015 03:53 pm »
The interesting part of Solar Probe Plus was that it payed for half the development of Star 48GXV. It might not cut it for SPP, but what about direct trajectory that takes as long as the Altas V VEEGA but saves the pass through the Venus environment? It could still be cheaper than the Atlas V, or at least reduce requirements and thus risk.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #766 on: 02/17/2015 09:41 pm »
https://astrobiology.nasa.gov/calendar/europa-plume-workshop/


Workshop on the Potential for Finding Life in a Europa Plume

DATE: Wednesday, February 18, 2015

TIME: 8:30am – 5:30pm PST

LOCATION: NASA Ames Research Center, Building 152, Moffett Field, California

On February 18, 2015, the NASA Astrobiology Institute (NAI) and the Solar System Exploration Research Virtual Institute (SSERVI) will co-host the workshop at NASA Ames Research Center, Moffett Field, California.

Current Europa missions under study by NASA are focused on answering the question “Is Europa habitable?” However, the potential presence of water plumes on the satellite could present an opportunity to pursue the question “Is there life on Europa?” Answering this question is far more challenging because measurements currently possible may provide only ambiguous results from a mission that either orbits or flies by Europa at relatively high velocity. To that end, NASA’s Planetary Science Division is convening a workshop to consider strategies to investigate Europa’s putative plumes for evidence of life. Invitees will be asked to provide feedback to NASA on the following key questions:

    What measurements are needed to detect and characterize the presence of life in an acquired sample?
    What instrumentation is needed to perform these measurements, and what is the current flight readiness of such instruments?
    What is the amount and nature of the sample needed by these instruments and what sample preparation is necessary?
    What constraints does the required nature of the sample place on the sample acquisition process?
    What challenges are present to acquiring the necessary sample and obtaining life-detection measurements from a cubesat(s) deployed by a Europa mission?

The workshop will be followed by a meeting of the Outer Planets Assessment Group on Feb. 19-20, also held at the Ames Research Center.

Offline tul

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Re: Proposed Europa Missions
« Reply #767 on: 02/19/2015 09:20 pm »
I've got a question. Since Europa's surface is made of ice, I guess it changes over the years. So if the Europa Clipper will map the surface after it will arrive, how Long can you use this data for planning the landing of an Europa Lander?

Online ugordan

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Re: Proposed Europa Missions
« Reply #768 on: 02/19/2015 09:36 pm »
Long enough. Europa's surface may change quickly on geological timescales, but not on human timescales. If there are regions that change "rapidly" due to plumes, diapirism or what not, they're likely going to be quite localized.

Offline redliox

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Re: Proposed Europa Missions
« Reply #769 on: 02/20/2015 08:06 am »
The OPAG is having its meeting now.  Thursday they talked largely about Europa and Pluto.  Today (Friday) it looks like they're having an update on current missions and mentioning plans for various small probes to the Outer Planets.  With luck we'll be getting some intriguing updates soon!
"Let the trails lead where they may, I will follow."
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Offline Blackstar

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Re: Proposed Europa Missions
« Reply #770 on: 02/20/2015 05:53 pm »
There was some interesting discussion of Europa Clipper yesterday. One speaker walked through the decision to use solar panels. A bunch of things led to that decision, including gaining confidence with the Juno work and some extensive testing. One interesting thing he said was that they did a lot of testing of spare Juno solar cells and they worked out well. However, there are better solar cells available (in terms of power generation) and they hope to investigate them. In other words, they can do the mission with the Juno solar cells, but it is possible that they might get even better results, but they won't know until they've done that investigation.

Also some discussion of SLS and what it brings to the table. One question was whether they can add mass to the SLS mission. The speaker said that it is possible to add some mass, but not a lot. Add too much and they will have to change the trajectory to do a flyby. He didn't provide numbers, however.

There were also some questions about the timeline. NASA has announced that they will be accepting instrument proposals. People wondered if the timeline that is assumed in the authorization bill means that development has to start now, and if NASA's timeline for instruments is incompatible with that. The answer was that NASA's instrument selection timeline is consistent with the timeline in the budget.

On Friday there was some discussion about the "billion dollar Europa" studies.
« Last Edit: 02/20/2015 06:08 pm by Blackstar »

Offline Blackstar

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Offline Zed_Noir

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Re: Proposed Europa Missions
« Reply #772 on: 02/21/2015 01:54 am »
http://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9A

Europa Clipper Team Seeking Earlier Launch

So I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?

Offline ccdengr

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Re: Proposed Europa Missions
« Reply #773 on: 02/21/2015 03:26 am »
NASA has announced that they will be accepting instrument proposals.
In fact NASA had an AO last year for Europa instruments ( http://www.nasa.gov/press/2014/july/nasa-seeks-proposals-for-europa-mission-science-instruments/ ) and the selections are supposed to be announced in April -- though what the relationship between that AO and an actual flight project was never all that clear.

Offline Star One

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Proposed Europa Missions
« Reply #774 on: 02/21/2015 08:45 am »
http://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9A

Europa Clipper Team Seeking Earlier Launch

So I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?

I suppose Falcon Heavy might still be too new a launcher to be entrusted with such an important mission, as I get the feeling that the dispensation that SLS gets on this wouldn't be applicable to another newish launcher. Especially as from what I have read on here they need to develop a high energy upper stage for it to be used on missions such as this.
« Last Edit: 02/21/2015 11:04 am by Star One »

Offline yokem55

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Re: Proposed Europa Missions
« Reply #775 on: 02/21/2015 01:52 pm »
http://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9A

Europa Clipper Team Seeking Earlier Launch

So I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?

I suppose Falcon Heavy might still be too new a launcher to be entrusted with such an important mission, as I get the feeling that the dispensation that SLS gets on this wouldn't be applicable to another newish launcher. Especially as from what I have read on here they need to develop a high energy upper stage for it to be used on missions such as this.
By 2022, even only flying a few times per year, falcon heavy will have ~20 flights under its belt. If they add a centaur/rl-10 based upper, the risk is in the integration and ground ops, not the upper stage itself. SLS has its own risk structure as well, and there are some planetary folks still sore about being politically married to a launcher.

Offline baldusi

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Re: Proposed Europa Missions
« Reply #776 on: 02/21/2015 02:40 pm »
http://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9A

Europa Clipper Team Seeking Earlier Launch

So I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?

I suppose Falcon Heavy might still be too new a launcher to be entrusted with such an important mission, as I get the feeling that the dispensation that SLS gets on this wouldn't be applicable to another newish launcher. Especially as from what I have read on here they need to develop a high energy upper stage for it to be used on missions such as this.
By 2022, even only flying a few times per year, falcon heavy will have ~20 flights under its belt. If they add a centaur/rl-10 based upper, the risk is in the integration and ground ops, not the upper stage itself. SLS has its own risk structure as well, and there are some planetary folks still sore about being politically married to a launcher.
You can't add that. The four options are:
1) Atlas V 551 (gotta watch for replacement by NGLV)
2) SLS
3) Delta IV Heavy with kick stage (something like OrbitalATK's Star 48GXV)
4) Falcon Heavy (non cross feed) with something like OrbitalATK's Star 48GXV or whatever Aerojet comes up with.

Offline Star One

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Re: Proposed Europa Missions
« Reply #777 on: 02/21/2015 03:06 pm »
http://spacenews.com/europa-clipper-team-seeking-earlier-launch/?_wcsid=FBF7A9E96BE3C2239D3BAF4A4638A03433FDA26192541BE07BCB7699D6C55D9A

Europa Clipper Team Seeking Earlier Launch

So I am guessing that the SLS launcher option is iffy for a 2022 launch. What are the alternate launcher options?

I suppose Falcon Heavy might still be too new a launcher to be entrusted with such an important mission, as I get the feeling that the dispensation that SLS gets on this wouldn't be applicable to another newish launcher. Especially as from what I have read on here they need to develop a high energy upper stage for it to be used on missions such as this.
By 2022, even only flying a few times per year, falcon heavy will have ~20 flights under its belt. If they add a centaur/rl-10 based upper, the risk is in the integration and ground ops, not the upper stage itself. SLS has its own risk structure as well, and there are some planetary folks still sore about being politically married to a launcher.
You can't add that. The four options are:
1) Atlas V 551 (gotta watch for replacement by NGLV)
2) SLS
3) Delta IV Heavy with kick stage (something like OrbitalATK's Star 48GXV)
4) Falcon Heavy (non cross feed) with something like OrbitalATK's Star 48GXV or whatever Aerojet comes up with.
SLS aside would all the others need gravity assists?

Offline vjkane

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Re: Proposed Europa Missions
« Reply #778 on: 02/21/2015 03:08 pm »
NASA has announced that they will be accepting instrument proposals.
In fact NASA had an AO last year for Europa instruments ( http://www.nasa.gov/press/2014/july/nasa-seeks-proposals-for-europa-mission-science-instruments/ ) and the selections are supposed to be announced in April -- though what the relationship between that AO and an actual flight project was never all that clear.


Actually, now that I think about it, I may have mis-heard Jim Green yesterday. He may have said that the instrument selection is slipping from April to September. (I thought he was discussing the Discovery program, but I might have confused the two.)
I heard Green say that the Discovery down selection had slipped to September-ish.  They received 28 proposals.

As for the instruments, since the Clipper was not an approved mission, they could formally solicit instruments for the mission, just for some possible future mission that might resemble the Clipper or might by an orbiter or might be...

This seems to have been one of those wink, wink moments where the letter of the law was followed but everyone knew what was going on.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #779 on: 02/21/2015 04:28 pm »
Where did you hear 28 Discovery proposals? On Thursday Green said that he did not know how many they received. I heard Alfred McEwen say 28, but 28 was the number last year and I assumed that he made a mistake when he said that was the number for this year.

 

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