Nasa Picks "juno" As Next New Frontiers Mission Options

[dvandorn]

The other real difference between potential Martian and Europan life is that Martian life, if it exists today, is likely to be very, very simple -- bacteria at best. Whereas if Europa has developed life, there are fewer reasons to believe that it would *have* to be very simple. With an aquatic environment and enough heat from within the moon's rocky core, Europan life has no greater obvious evolutionary limits than Earth's sea life does.

As much as finding fossilized bacteria, or even live bacteria, on Mars would prove a point and be interesting in and of itself, it wouldn't give us a whole lot of data on how life might develop outside of Earth's influence. Multi-cellular organisms (or their equivalent) in Europa's oceans would demonstrate how life might be able to organize itself in different ways to those we see on Earth. For example, would genetic encoding be DNA-based? Or has Europan life found different ways to organize, evolve and propogate?

I think the most boring thing we could possibly find on Europa would be -- fish. Regular old fish, with scales and gills and DNA and everything. But it would sure hint at some common ancestor to life on both worlds, wouldn't it?

My bets are on truly alien life forms swimming in Europa's oceans, whether they look like fish or not.

-the other Doug

[tedstryk]

  The camera, according to Bolton, is the lowest-priority of the lot

Yes, but if it is small and simple, it is unlikely to be cut, given its PR value - There is no point in making cuts that don't save much money, weight, or power unless you are really desperate.

[tedstryk]

But, with a lander or not, I think Europa Orbiter is finally definitely going to fly -- quite posibly as a collaboration with the ESA, which has recently officially declared itself very interested in such a teamup.  NASA has finally been forced to get serious about this mission, as they finally were with the Pluto probe.

I hope so, but I am biting my nails considering it seemed quite definite in the late 1990s...lets hope it doesn't get tied to a political push again.

[garybeau]

That being said, providing Europa Orbiter with enough fuel to break back out of Europa orbit is simply impractical -- it will be hard to carry enough even to put it into Europa orbit in the first place.  This is a difficult mission.  We will, instead, just have to make sure it's properly sterilized (as we'll have to do in any case with all Europa landers).

Thanks for all the info you provided. I hadn't heard about a Nasa/ESA cooperative effort for a Europa orbiter That's great news I hope the plans don't get stalled.

If leaving a Eurpan orbit is not practical, I guess the next best thing to do is leave it in orbit and let the intense radiation sterilize the craft. Once in orbit, how long would a spacecraft remain in an orbit around Europa? With little or no atmosphere, I would think a spacecraft would remain there for quite a few years. Are there other factors that would cause the orbit to decay such as tidal forces or resonant forces from the other moons?

I read the link that you provided from The National Academies on Preventing the Forward Contamination of Europa. I'm not sure if I share their optimism on the ability to satisfactorily sterilize a spacecraft. Even by their admission, a spacecraft will never be 100% free of biological organisms or spores, but only reduced to an acceptable level. I remember the surprise and disbelief when a piece of the Surveyor lander was brought back and Streptococcus bacteria were found to be still alive inside the camera. They were exposed to the vacuum of space, zero moisture, extreme temperature swings (night and day on the moon are 14 days long) and they were there for almost three years.
The biggest fear would be if the spacecraft missed it's orbital insertion target (i.e. Mars Climate Orbiter) and impacted directly into the moon. Without an atmosphere to slow it down, it would impact hard and pieces would most likely be buried under a protective layer of ice. I am still 100% for a Europa orbiter, but I think that we have an obligation to keep the risk of contamination as close to zero as we can. At least until we can confirm if any life currently resides there.

[JRehling]

Three miscellaneous comments for this thread, from the concrete to the fanciful:

1) Orbits around Europa are very unstable due to the presence of other gravitational sources in the vicinity (the same is true of the Moon, but of course, Jupiter is much pushier than Earth gravitationally). So whenever the craft dies, it will not be long in impacting Europa's surface. Months, not years.

2) It is not believed that a europan ocean would have enough energy to support advanced life. That is surely somewhat speculative, but take that for what it is. The suspicions lean towards bacteria or nothing.

3) If (2) were wrong, the presence of, eg, fish would not point to a common origin. Earthly biota have reinvented key phylogeny properties many times. For example, "tree"ness has evolved very many times, on separate family branches. I think we can be dead certain (NPI) that fish would not make the ride from/to Earth to/from Europa on meteorites, in any form whatsoever.
If we do find life elsewhere, macroscopic resemblance would be a much less convincing evidence of common origin than molecular resemblance. Chirality to start with, use of the DNA codons vs. RNA codons in equivalent roles next. Someone with biology training past ninth grade could comment on others.

[Redstone]

The original concept for a Europa Orbiter was not a multi-billion dollar, nuclear propulsion behemoth, but rather a <1 billion scout mission with radar and imaging capabilities. The proposed mission had overwhelming support from both the public and scientific community.

It's only because of the shortsighted, politic driven decision making that that this mission has been "on again - off again" so many times. Fortunately, NASA is not the only game in town any more. Maybe we will see an ESA Europa mission while NASA is trying to find its way.

While a NASA only Europa mission may not be "on" right now, here's another Griffin quote made to the press on May 12:

The Science Mission directorate wants to do a Europa mission, the National Academy of Sciences wants to do a Europa mission, I want to do a Europa mission. When we can afford it in the budget, we'll do it.

Sounds like a NASA mission is still on the cards, but we just need to wait a while. Remember Griffin is focussing on the manned program right now, the JUNO announcement notwithstanding. Once the ISS and CEV plans get settled in a few months, I'd expect Griffin to turn to the long-term detail of the space science program.

[Bob Shaw]

Some comments on life on Mars (and elsewhere) and on Surveyor 3:

Life isn't divided into success and failure by 'simplicity' and 'complexity' - the only 'success' is survival of the organism through it's offspring (so human intelligence and fecundity may well not be good success strategies). The sophistication of 'simple' Martian/Europan life may not be obvious to a big game hunter, but a microbiologist might well disagree. Let's not get hung up on macro-organisms!

And sadly, there's a persuasive view of the Surveyor 3 camera which suggests that the bacteria found within it were due to laboratory contamination, so the jury has to still be out on the survival of spores etc in space.

Considering the early bombardment history of the planets, plus the recent claims of an equally early warm and wet Earth I'd be unsurprised to discover that life on Earth and Mars share a common ancestry (or are at least distant cousins, survivors of crustal reformatting by giant impacts and natural interplanetary flight).

If and when we ever see a substantial industrial base on the Moon, then that's the place to look for meteorites bearing the early signs of life - or maybe even smaller bodies, like asteroids, Phobos and Deimos, comets...

[JRehling]

I would have thought / hoped the next Jovian mission would have been a Europa orbiter. This is one of the few places besides Mars that holds any prospects for life.  Whatever happened to Nasa's "follow the water" mantra. The Juno mission just doesn't stir up any passion.

Well, forget for a moment the sibling (parent) rivalry between Jupiter and the other worlds near it.
What we're talking about here is Jupiter -- one of the three most central planets to space exploration -- finally getting its Pioneer Venus, finally getting its Mariner 9. Among the worlds that have had orbiters (preCassini), one that is totally unique in structure and atmosphere. And with Galileo's Jupiter science having been a mere trickle, one that has been seen more like a world that's received six flybys than has ever been the subject of an orbiter's science in the way that Mars has received six, and Venus several (mainly Soviet, but two American).
It's got an atmosphere that is in some ways (thick water clouds, for one; sweeping storm fronts bearing rain) more earthlike than either Venus's or Mars's. A structure which is totally unlike that seen in the inner solar system. And note that Cassini is not giving Saturn the look that Juno would give Jupiter. Cassini's closest approach to Saturn already has taken place, and it wasn't even looking at the planet. Saturn's rings are both a barrier for close approaches and a factor that neutralize the particle environment that we want to see at Jupiter. Remember, Jupiter is our best analogue to most of the extrasolar planets we've discovered, and knowing it better could prove essential, obliquely, to our efforts to find earthlike planets sharing those systems with giant neighbors.
I don't think the first *real* Jupiter orbiter is a low-passion mission at all. With its camera a minor player, it may rank low in terms of (intended) eye candy, but planetary science is a forensic science, and fingerprints may seem less exciting than photos of a corpse, but they can be more telling about the history.
I'm excited about Juno -- even eye candy should be forthcoming. But I'm pretty curious about what's beneath the hydrogen. Whether it's 1 earth-mass or 30 earth-masses may have little visible effect at the surface, but the result will tell us a lot about origins. And given that the source of magnetic fields remains a bit of a mystery (eg, Mercury's; the large differences between those of the giant planets), more information on that matter is going to be welcome as well.

[tedstryk]

I think the six-flybys analogy is a good one (seven if you count Ulysses Jupiter Distant Flyby a year or two ago which did yield some interesting particle and fields data, particularly with regards to dust from Io) in terms of data return, although it was over an extended period of time, so for things such as Io coverage, it at least had a long temporal baseline. I see it as a series of mini-flybys. I do hope that an Amalthea flyby can be squeezed into Juno. It will be penatrating in that far, and I don't see another spacecraft doing that for the forseeable future (I don't think it would be good to even risk an Io mission). It is a shame Galileo didn't take remote sensing data. Given its illness and how badly it got zapped however, had it been making turns to do imaging at the time of the encounter at first Io and then Amalthea, it would likely have at least safed, costing us the data on the near-Amalthea particles, a lot of particle and fields stuff, and we might have lost the spacecraft all together. The budgetary issues non withstanding, I would have loved Galileo images close to Amalthea, but I am skeptical the spacecraft could have pulled it off. I have been working on some of the images Galileo took, and it is a very interesting world, especially given the new shape-model release. I have worked hard on the high resolution E26 image, and you may have seen my result - it is faux-super-res, created by stacking various resamplings and processings of the same image. It creates a relatively sharp image despite oversampling, although it doesn't truly increase resolution. I also tried to correct overexposure in part of the image.

Also, have worked on the only three Galileo color images of Amalthea, taken during the primary mission. I created color images using the various filter combinations available (the E4 data had a fourth filter available, but I didn't use it for color). I also used all available images (3 for G2 and C3, 4 for E4, although the E4 data was so distant it really wasn't worth it) to creat super resolution black and white images. I then overlaid the color data on these. Here is the result:

[Bjorn Jonsson]

I vaguely remember reading somewhere that Juno will be spin-stabilized, probably making it difficult to obtain high-res images of satellites like Amalthea or even Io during fast flybys. Or maybe I'm confusing Juno with something else (Inside Jupiter/JASSI etc.). Does anyone know if it will be spin-stabilized ?

[Guest_BruceMoomaw_*]

Yeah, it will be -- which will certainly interfere with any imaging during a flyby, but would not make it impossible (or so low-quality as not to be worth the effort). Again, I intend to contact Bolton for more on all this in the very near future.

[Stephen]

But the catch is whether they can design a lightweight sampling system for the mass spectrometer that could penetrate deep enough into the ice to get below the upper layer of Europan regolith where any biological organics have been unrecognizably scrambled by Jupiter's radiation -- probably a couple of meters.  If they can't, I don't think a piggyback lander is worth flying.

On that last score I note that someone wrote in a recent scientific paper titled To Land on Europa:

The JIMO SDT report calls for a capability to sample to a depth of ~ 1 m. Our preliminary work suggests that it is unlikely that this will be accomplished under the present constraints. Innovative, light weight systems for active sampling to depths of several cm have been evaluated; a lander including such a system could weigh in at less than the allocated 375 kg. However, if the science community strongly desires sampling to depths of ~ 1 m, we believe it will be necessary to significantly increase the lander total mass allocation from its present level.

Should that prove to be the case, if you want to be able to drill even deeper ("a couple of meters") I guess that would mean an even bigger increase in the lander's weight.

[Guest_Myran_*]

dvandorn wrote:

"I think the most boring thing we could possibly find on Europa would be -- fish. Regular old fish, with scales and gills and DNA and everything. But it would sure hint at some common ancestor to life on both worlds, wouldn't it?"

Its true that active swimmers would have to be streamlined to travel efficiently in water, but no or extremely little oxygen would mean no gills and active swimming less likely. (No photosynthesis possible under a mile of ice).

If there any life on Europa its more likely to be colonies of organisms gathered around warm springs getting their nourishment from chemical processes, what shape they might have im not qualified to even speculate about. The big question is if liquid water and volcanic heat is enough to get life started.

-"-

As for sampling and investigating deeper down: The idea of a robot that melts itself down to reach any possible ocean beneath the ice is a clever idea, but its not even on serious consideration so I wont see it in my lifetime.

[JRehling]

As for sampling and investigating deeper down: The idea of a robot that melts itself down to reach any possible ocean beneath the ice is a clever idea, but its not even on serious consideration so I wont see it in my lifetime.

(GOING STILL FURTHER OFF TOPIC, HERE)

Back in the salad days before we knew so much, it seemed possible to melt through the ice. But two compounded difficulties pretty much kill that idea. One, the ice is much deeper than we might have hoped. 20 km seems to be the direction that the evidence is pointing. Then, the factor that makes that especially lethal is that if the ice has any impurity at all, melting through it would cause the impurity to accumulate at the bottom of the hole, eventually creating a mass of salt or somesuch, which heating to 10C would not make go away.

Enceladus could stand in as a new arena for the exact same hopes. Cassini's early imaging seemed to deflate those hopes, for, although Enceladus showed young surface, it also showed considerable relief, which means the ice must be relatively thick (even when you allow for the very weak gravity). But, the last flyby of the south pole showed "tiger stripes" analogous to Europa's triple bands, and nonimaging instruments indicate that H2O seems to appear in Enceladus's vicinity at a considerable rate -- these results may combine to indicate that live geysers exist at high latitudes, which would provide a possible point of axis for a Enceladus Underwater Explorer (???). Not to help Myran too much, though -- I don't see that happening in our lifetimes, either!

[Decepticon]

They are sending a Probe to Jupiter and according to this article Europa Ganymede and Callisto will not be studied?!?!


EUROPA should be Number 1 on the priority list.


I'm so upset by this article. http://www.space.com/searchforlife/seti_juno_050609.html