NASA Europa Missions, projects and proposals for the 2020s Options

[vjkane]

If there's a reflective mode, radar can determine smoothness/roughness at the scale of the wavelength, which is much smaller than the scale of the footprint. But that's ambiguously confounded with other properties of the surface, and I don't know if the data will be useful for that purpose.

Surface roughness within the beam footprint can be determined. I believe the footprint is pretty relative to safe landing areas in the interesting areas.

[Explorer1]

ESA wants to jump in now too, with an unspecified addition of some kind:
http://spaceflightnow.com/2016/01/05/esa-w...sion-to-europa/

[scalbers]

Without getting too political, it's interesting that Congress has mandated a lander be included, so ESA collaboration (hinted at last year) may be a great way to accomplish this. And indeed the Europeans want to be involved in a mission to their namesake moon.

[antipode]

This could be the moment where high speed penetrators (maybe 2 in that mass budget?) finally get their much delayed moment in the (dim) sun.

P

[nprev]

As I recall, penetrators have been proposed in the past but the unknown level of roughness at small scales (i.e., angular surfaces) combined with the hardness of ice at Europa's temperature introduce a LOT of risk...and this is not a mission that can be reflown easily or soon.

My (completely amateur) dream design would be a tiny analog of MPF with a retro assist; let it bounce around & open up the petals. Small panoramic camera, a little arm to stab the surface & measure regolith (cryolith?) conductivity & maybe other things, a UHF uplink to the orbiter, and as big a battery as they could fit onto it.

[Explorer1]

How plausible are solar panels for such a mission? Juno has it easy being an orbiter, with plenty of wingspan, but how large would efficiency advances in the next half decade have to be to make them worth it for extending a surface mission's duration?

[katodomo]

Beginning-of-life efficiency on current production GaAs triple-junction solar panels is close to 30% (InSight's panels are 26% iirc). Fraunhofer ISE designed some solar cells with up to 45% efficiency in 2013, which I think is still the record.

At Jupiter's distance with minimal absorption by Europa's atmosphere 45% would yield 22.5 Watt per square meter. Given time-to-travel, after three years that'd probably be around 80-85% of that, and after one year near Jupiter around 65-70%. Hence about 14.5 W/m² assured yield with theoretical high-efficiency solar panels, up to about 8.5 W/m² with what's currently employed (for comparison: Juno's panels are expected to yield around 6.0 W/m² at life end, about 3.5% more than what's needed for operations).

Pretty much not feasible on solar alone. Possibly feasible with relatively large panels (3+ m²) combined with RHUs, provided rather minimal operations after a battery-powered first science phase and bouncing communications via a nearby space unit (i.e. flyby Clipper or orbiter). For ease of comparison, a single MMRTG at Jupiter distance would be pretty much equivalent to around 7.5 m² solar panels at the above high efficiency, or about 13.0-13.5 m² at current off-the-shelf efficiency.

[Explorer1]

Thanks for the info; looks the weight constraints are such that anything but batteries is still a no-go? I suppose it's now a question of how long a battery would last, like Huygens....

[katodomo]

There's a JPL analysis on that here:
http://www.lpi.usra.edu/opag/meetings/aug2...1_beauchamp.pdf

Covers pretty much all that, including weight constraints, batteries etc.

[Jaro_in_Montreal]

Lander rocket exhaust effects on Europa regolith nitrogen assays
Ralph D. Lorenz,
Johns Hopkins University Applied Physics Laboratory

http://www.sciencedirect.com/science/artic...032063316300484

• Europa soft-landing is particularly susceptible to ammonia exhaust deposition on cold surface.
• Europa may be starved of nitrogen so its compounds are of particular interest as limiting nutrients.
• Abundance, nature and isotopic compositions may be affected by exhaust deposits.
• Lunar, Mars landings suggest a region ~9 m around a 200 kg lander will be affected.

[Guest_Steve5304_*]

Lander rocket exhaust effects on Europa regolith nitrogen assays
Ralph D. Lorenz,
Johns Hopkins University Applied Physics Laboratory

http://www.sciencedirect.com/science/artic...032063316300484

• Europa soft-landing is particularly susceptible to ammonia exhaust deposition on cold surface.
• Europa may be starved of nitrogen so its compounds are of particular interest as limiting nutrients.
• Abundance, nature and isotopic compositions may be affected by exhaust deposits.
• Lunar, Mars landings suggest a region ~9 m around a 200 kg lander will be affected.

Surprised they would even consider a crane style landing and not a higher up retro rocket and bubble landing like a Soviet Mars 3 in 71... I know its not a rover mission, but I would hate to waste all the time and money just to get a sterilized sample of the surface showing jetfuel. It certainly could be done.

https://www.youtube.com/watch?v=Twgb41iAF2A

I'm very excited about this mission because of the lander. Even if it doesn't have camera's (And its possible it wont)

[Explorer1]

Science definition report completed (with lander concept art!) https://www.nasa.gov/feature/nasa-receives-...-lander-concept

[Habukaz]

The SDT was tasked with developing a life-detection strategy, a first for a NASA mission since the Mars Viking mission era more than four decades ago. The report makes recommendations on the number and type of science instruments that would be required to confirm if signs of life are present in samples collected from the icy moon's surface.

My life-detection strategy: look for whale bones.

ADMIN: Good one, but please review rule 1.3. Letting this post stay up for now because we're discussing possible policy revisions, but we do ask that everyone please refrain from biological discussions. Thanks!

[bobik]

A brief description of the Joint Europa Mission (JEM) proposal submitted to the M5 call of ESA.

[Roby72]

https://spaceflightnow.com/2017/03/16/trump...l-partnerships/

Europa multiple flyby mission is supported in these budget blueprint but an expensive lander mission is cancelled

Robert