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On to Europa?

With the 2016 budget cycle beginning, it’s heartening to see that Europa factors in as a target amidst a White House budget request for NASA of $18.5 billion, higher than any such request in the last four years, and half a billion dollars more than the agency received in the 2015 budget. This follows Congress’ NASA budget increase of last year. Casey Dreier, who follows space policy issues for The Planetary Society, cites what he calls a ‘new commitment to Europa’, as seen in a request for $30 million to start the mission planning process. Dreier adds:

At its most basic level, it means that NASA can pursue the development process to create a mission to explore Europa. That’s new, and that’s important. Europa has moved from “mission concept” to “mission,” with details to figure out, plans to draw, teams to assemble, and hardware to build (eventually). It’s a step that Congress could not force NASA to take (NASA being an executive branch agency and all) no matter how much money it gave to them. The White House and NASA deserve credit for deciding to pursue this mission. In fact, I believe that this budget will occupy a small place in history as document that officially began the exploration of Europa.

I leave you to Dreier’s analysis for details about other budget components so we can focus this morning on Europa. But do keep in mind that while we’re only at the beginning of a budget debate, documents like these are nonetheless critical in setting the terms under discussion and keeping key mission ideas current. While we’ve seen huge changes in direction and mission targets over the past fifteen years, the persistence of Europa as a focus for robotic exploration is heartening, and it’s a focus buttressed by the outstanding results from Cassini at Saturn.

The Europa Clipper mission that may emerge from all this bears in its projected operations a certain similarity to Cassini, in that over the years since the latter began orbiting Saturn, we’ve learned a huge amount about Saturn’s moons from flybys. Just as Cassini has opened up detailed study of Titan, Europa Clipper would be an orbiter that would make forty to fifty flybys of Europa’s surface during its primary mission. This will demand a highly elliptical orbit aimed at minimizing radiation damage and a spacecraft heavily shielded against dangerous particles.

EuropaClipper

Image: Concept to achieve “global-regional coverage” of Europa during successive flybys. Credit: NASA/JPL-Caltech.

So no landing on Europa — not at this stage of the game — but a series of close Europa flybys at altitudes ranging from 2700 kilometers down to 25 kilometers would give us priceless information. If the moon really does have geysers that vent water from the presumed deep ocean below the ice, a spacecraft this close to the surface could take samples, in addition to giving us close-up views of the reddish veins that so distinctively mark the crust, possibly containing organic compounds that may be involved in cycling between surface and sea.

Also positive is the news that the current budget request will contain funding for the instruments NASA intends to contribute to the European Space Agency’s Jupiter Icy Moons Explorer mission (JUICE), which is to launch in 2022 (see Jupiter Icy Moons Explorer). Arriving in Jupiter space in 2030, the mission is to spend several years studying not just Europa but Ganymede and Callisto as well, all three being candidates for subsurface oceans. After flybys of Europa and Callisto, (including measurements of the thickness of Europa’s crust), the spacecraft will enter orbit around Ganymede to study the surface and structure of the only Solar System moon known to generate its own magnetic field.

This JPL page on Europa Clipper notes that it too would make flybys of Ganymede and Callisto, but only for the sake of orbital adjustments, the primary mission being Europa. There, the campaign would consist of four segments designed to produce maximum coverage of the surface under consistent lighting conditions. From the document:

During each flyby, a preset sequence of science observations would be executed. On approach the spacecraft would perform low-resolution global scans with its IR spectrometer (“nodding” the spacecraft’s field of view back and forth across the moon, much like the Cassini spacecraft does during its moon flybys), followed by high-resolution scans with that instrument. At 1,000 km the ice-penetrating radar, topographic imager and ion and neutral mass spectrometer (INMS) would power up. The radar pass would occur from 250 miles (400-km) inbound altitude to 250 miles (400-km) outbound altitude, during which stereo imaging and INMS data are acquired continuously. During departure, the IR spectrometer would conduct additional high- and low-resolution scans as the spacecraft moves away from Europa.

And apropos of yesterday’s discussion of CubeSats, I want to note that NASA is looking at proposals from ten universities for CubeSat concepts to enhance Europa Clipper, an announcement that was made last October. The idea here is to carry small probes as auxiliary payloads that would be released in the Jovian system for further measurements of Europa. According to the agency, the science objectives for potential CubeSat probes include reconnaissance for future landing sites, gravity fields, magnetic fields, atmospheric and plume science, and radiation measurements. The latter may be a showstopper, in my view, given the radiation environment in which these diminutive spacecraft would be forced to operate.

So the outer planet news is at least momentarily positive, and as Phil Plait reminds us in NASA Has Its Sights Set on Europa, the Europa Clipper mission has a strong champion in Congress in Rep. John Culberson (R-Texas), whose support has been useful to NASA in past debates. With a launch in the early 2020s and a 6.5-year journey to Jupiter that includes gravity assists around Venus and (twice) the Earth, Europa Clipper could open up the next phase of outer planet exploration, followed shortly thereafter by the arrival of JUICE. That would make the years around 2030 a golden era for our understanding of Jupiter’s provocative moons.

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  • Hop David February 4, 2015, 14:02

    I’ve always thought that the icey moons with internal oceans are a better bet to find life than Mars. So I’m excited to hear this.

    Another icey moon that evidently has liquid sub surface oceans is Saturn’s moon Enceladus. Saturn’s radiation belts are a lot milder than Jupiter’s. And I believe Enceladus’ geysers are better established than Europa’s.

    If they develop technology for sampling Europa’s geysers, hopefully they’ll be able to use it to look at Enceladus.

  • Andrew LePage February 4, 2015, 14:47

    “If the moon really does have geysers that vent water from the presumed deep ocean below the ice, a spacecraft this close to the surface could take samples, in addition to giving us close-up views of the reddish veins that so distinctively mark the crust, possibly containing organic compounds that may be involved in cycling between surface and sea.”

    If these geysers do exist, it should prove possible to return samples of its particles to Earth using technology originally developed for NASA’s Stardust mission for detailed laboratory analysis as part a follow-up mission. Such a sample return mission would be MUCH less expensive and could be performed MUCH sooner than a mission designed to land on Europa.

    http://www.drewexmachina.com/2014/03/27/a-europa-io-sample-return-mission/

    A similar mission concept is currently under serious study to return samples from the much more active polar plumes of Enceladus.

  • Joy February 4, 2015, 15:34

    Sorry, but I would like to curb the enthusiasm for throwing money at Europa and making it the next black hole for astrobiology when the multi decade painfully slow (2016 will be 40 years post Viking!) examination of Mars comes to naught. The Europa Clipper would be the 10th mission to visit Jupiter, good grief.

    The geysers of Europa (if they exist) are likely quite intermittent. The Europa Clipper could complete its mission without getting a chance to “sniff” a plume. Recall that Galileo spent almost 8 years in the Jovian system and did not see any plumes from Europa. And frankly, as the motivation for a Europa mission is astrobiology, I do not see flyby imagery advancing that issue at all. All that would happen is some very tentative speculations which would be used to push for another inadequate mission in the 2040s or beyond.

    Yes, I am an old cynic. IMO, Europa was chosen, like Curiosity, the ISS, and the shuttle as a welfare program for the industry. The fact that it would be expensive, time consuming, and almost certainly scientifically inconclusive (requiring the next program) is not a bug, it is a feature.

    We KNOW that Enceladus has plumes. The argument for an Enceladus orbiter is much stronger than Europa. Guaranteed plumes to sniff and much lower radiation. Any mission to the outer planets would require a politically problematic RTG and not be cheap. But, at least there would be a much higher probability finding the holy grail of astrobiology, an extraterrestrial water sample. Of course if a plume is sampled and lacking in life signs, solar system astrobiology would be dealt a mortal blow, and the risk averse NASA planners are terrified of that. They remember 20 years in the wilderness after Viking failed to demonstrate life on Mars. (That is why Curiosity does not have any actual astrobiology instruments) Better to go to Europa, not sample a plume, and crow about how pretty the new pictures are.

    Don’t forget, we haven’t even taken a good look at Ceres yet. Ceres *may* have plumes, same as Europa – in a year we will know much more. As Dawn has shown, Ceres can be reached and orbited on a reasonable budget. No plutonium RTG needed and a low radiation environment makes this one a doodle. A near clone of Dawn could be dispatched with instrumentation for sniffing plumes much sooner than a Europa mission. Better yet, the pathway to a follow on Ceres lander is MUCH less problematic than a Europa lander. But Ceres will likely be neglected as it simply isn’t expensive enough to provide the job$ program that the industry demands.

  • G. Cecil February 4, 2015, 17:26

    Europa Clipper may become intertwined w/ the SLS, which has Congressional support but no mission funding. It would enable a direct route. The CubeSats are fascinating … deploy that fleet far enough out to follow indep. inbound trajectories but close enough to keep cumulative rad exposure down and write them off after data relay.

  • Enzo February 4, 2015, 19:36

    A LASER receiver on JUICE could really help cubesat missions once it has settled in Ganymede’s orbit at the end of its mission.
    The distance Europa-Ganymede is, at its minimum, similar to Earth-Moon and LASER communications between LADEE and Earth have reached 622 Mbit/s.
    Granted, that was with a large telescope receiver on Earth, but even 1/1000 of that bandwidth would be great.
    JUICE would then act as a repeater re-transmitting the data back to Earth.
    This could allow very low orbit, low mass missions (~10 Kg ?) that globally maps Europa at high resolution, store images and transmit them to JUICE at each Europa/Ganymede passage.
    I wonder if JUICE’s imaging system could be re-cycled as LASER receiver. Probably not, unless designed with that in mind.

  • Wojciech J February 4, 2015, 20:52

    Let’s hope this mission takes place.
    And after that Enceladus and Triton await. Our work is never over nor ceases to bring more wonders to behold ;)

  • Brett February 4, 2015, 21:12

    Is there any way the probe could tell how thick the ice is on one of its many passes? If there are geysers, and we can determine the thickness, then we can figure out a landing site where the ice is unusually thin and new – and look at that.

    Enceladus would probably be even better for that, since we know it has geysers that blast through whatever ice layer exists into space.

  • ljk February 4, 2015, 22:27

    Unmasking Europa: Of Ice and Controversy

    FEBRUARY 27, 2009

    You wouldn’t think the thickness of ice on a distant moon of Jupiter could emerge as something of a political hot-button, but that seems to be what has happened in the ongoing investigation of Europa. Thick ice or thin? The question is more complicated than it looks, because by ‘thin’ ice we don’t mean just […]

    Read the full article →

    https://www.centauri-dreams.org/?p=6351

  • ljk February 4, 2015, 22:28

    Europa: Thin Ice and Contamination

    APRIL 12, 2011

    These days funding for missions to some of the most interesting places in the Solar System is much in question. But sooner or later we’re going into the outer system to investigate the possibilities for life on worlds like Europa, Enceladus or Titan. The case for Europa seems particularly compelling, but we have to be […]

    Read the full article →

    https://www.centauri-dreams.org/?p=17515

  • Rob Flores February 4, 2015, 23:18

    This mission seems a bit too limited to me. It is not neccessary to
    put an orbiter around Europa to study it. It should be possible to
    plan many orbits that fly-by Europa,Ganymide, Calisto (and very
    infrequently to Io, a fair Delta V is probably needed there compared
    to outer moons).
    Once in orbit around Europa, why cant an orbiter carry and launch
    a sub-unit that allows closer imaging of the surface, though no landing,
    I mean it’s crystal clear down there. And if you time it right, you get
    to see a surface approach of europa before the sub-unit impacts.

  • william February 4, 2015, 23:31

    A huge waste of time and money! This is a poor choice of limited resources better to go to Saturn’s moon Titan where they know they have seas already on the surface, and perhaps unique biochemistry there

  • Andrew LePage February 5, 2015, 1:13

    @Joy February 4, 2015 at 15:34

    I have no idea what is the cause of your anti-Europa rant but you desperately need to get your facts straight. During the last quarter century, the United States has accomplished NINE successful missions (plus three failures) to Mars including five missions that have landed on its surface. During this same time the US has launched exactly ONE mission towards Jupiter, Juno, which will not arrive there until next year and which will not study Europa in any substantive way. The facts show that the lion’s share of NASA’s planetary exploration budget has been directed towards the continued exploration of Mars for a generation now – and rightfully so. Sending one mission to study a promising astrobiological target like Europa at a fraction of the cost of the $2.5 billion cost of NASA’s ongoing Curiosity rover mission is hardly cause for any concern whatsoever in my book since exploration of Mars will continue to be a top priority into the foreseeable future.

    As far as your reference to the upcoming 40th anniversary of the Viking mission, the one thing that we learned from this mission is that looking for extraterrestrial life is MUCH harder than was originally supposed when development of its instruments started a half a century ago. It is now recognized that many of the assumptions used to design these instruments were just plain wrong and that they would have a difficult time detecting most terrestrial microbes. This is why NASA has taken a much more cautious and measured approach towards its exploration of Mars over the last quarter century trying to learn more about its environment while at the same time carefully crafting better approaches to detecting life on Mars based on those findings. This process takes time and equipping Curiosity with another ill-designed biological experiment would have been a waste of valuable scientific payload space. I’d suggest reading the following:

    http://www.drewexmachina.com/2014/05/25/the-new-search-for-life-on-mars/

    Getting back to Europa, Galileo has shown Europa to be a very promising target for continued exploration with a tidally-heated ocean definitely present below its icy crust. But you also have to remember that Galileo’s severe communications issues limited the volume of data it could return. Galileo did not observe any geysers (assuming they exist) because it was never directed to make the types of observations required to detect for such phenomenon owing to the stark limits placed on the amount of data it could return. The small amount of available data that Galileo could return from Europa had to be allocated to tasks with a high probability of useful return.

    NASA’s next mission to Europa will be able to do MUCH more than just take pictures of its surface and “sniff” any emissions from geysers. One of the often-proposed instruments for this mission is a long-wave radar system designed specifically to probe the thickness the icy crust – information vital for not only assessing the the conditions of the ocean beneath but for designing future missions. While the exact instrument suite for the proposed mission has yet to be chosen (that process is currently underway), it will include many instruments to explore this biologically promising target.

    Finally, yes, Enceladus is known to possess very active geysers – certainly more active than ay Europa seems to have. It also shows much promise as a potential target of astrobiological interest. But a mission to this interesting moon will be much more expensive and take longer to develop than the currently proposed Europa mission which has been under study for decades now. That being said, there ARE serious studies being performed as we speak for new missions to Enceladus – missions that will benefit greatly from the experience learned from mounting a new mission to Europa. As for Ceres, with Dawn scheduled to assume orbit next month around this dwarf planet, we have yet to get our first good look at this world and its astrobiological potential is HIGHLY speculative. It would be the height of irresponsibility to place this unknown target ahead of proven targets like Europa.

    Your libelous statements about how planetary missions are purposely designed to be inconclusive as some sort of “welfare” program deserves no comment and, as a member of the scientific community, I find deeply offensive.

  • Ashley Baldwin February 5, 2015, 4:39

    I am excited about a Europa mission . I concede that Enceladus is well worth a look but after the extended Cassini mission it was inevitable that NASA would be obliged to look at Jupiter. My worry is that NASA are under increasing pressure to get quick , easy returns and it’s for this reason that they prioritise Mars. At dull but safe locations. The Insight mission was a classic and totally needless example of this , with an exciting Titan Lake mission on the short list and rejected. Given the issues surrounding exoplanet ice Giants and the discovery of ” mini Neptunes” and the controversy surrounding the point at which terrestrial planets turn into them ( or around some M dwarfs the opposite way) , there is a big scientific case for Uranus or Neptune missions. But these involve huge flight times and limited RTGs. Jupiter represents the perfect compromise and by the time the Clipper arrived it will have been 25 years since Galileo, apart from brief distant flybys by Cassini and New Horizons. The Clipper in conjunction with JUICE , will return tonnes of data with state of the art technology. I don’t count Juno as that is dedicated to the radiation and magnetic fields in a polar orbit and will contribute no “planetary” science.
    In terms of SLS and a direct flight , the limitation here is its half billion dollar cost which would add 25% to mission costs. What I don’t understand though is why not use a Falcon Heavy which is more than adequate to deliver a Clipper mass payload direct and quickly to Jupiter and at less than a quarter of the cost of SLS ? It’s due for its first flight in the next year, unlike SLS ,and by the early 2020s should more than have proved its credentials . Maybe we will see a change in mission planning to accommodate a rocket that could also open the outer solar system as it is capable of delivering meaningful payloads as far as Uranus at least.

  • EricSECT February 5, 2015, 7:02

    Joy stated; “…IMO, Europa was chosen, like Curiosity, the ISS, and the shuttle as a welfare program for the industry. The fact that it would be expensive, time consuming, and almost certainly scientifically inconclusive (requiring the next program) is not a bug, it is a feature.” and “…The argument for an Enceladus orbiter is much stronger than Europa. Guaranteed plumes to sniff and much lower radiation. Any mission to the outer planets would require a politically problematic RTG and not be cheap. But, at least there would be a much higher probability finding the holy grail of astrobiology, an extraterrestrial water sample. Of course if a plume is sampled and lacking in life signs, solar system astrobiology would be dealt a mortal blow, and the risk averse NASA planners are terrified of that. They remember 20 years in the wilderness after Viking failed to demonstrate life on Mars. (That is why Curiosity does not have any actual astrobiology instruments) Better to go to Europa, not sample a plume, and crow about how pretty the new pictures are.”

    Prior to reading this comment, something was eating at the back of my mind for a while, but I was not able to articulate it as well as Joy did.

    I fully agree with Joy. I am a huge Europa fan, but we should go with the sure bet (an Enceladus sample). NASA is much too risk adverse and politically correct (launch no RTG’s!!!)… pathetically timid in it’s search. NASA wants to play it out as long as possible, much like a welfare program. At this rate, it will be 100 years before we detect a second Genesis.

  • Lionel Ward February 5, 2015, 9:58

    With the climaxes of what look to be highly successful missions to Ceres and Pluto in the coming months, it’s the right time to be proposing bold new missions to congress and the public. Whether Europa’s plumes or Enceladus’s should be investigated first seems to be a controversial question and I was somewhat pursuaded by what Joy wrote above… Hopefully an Enceladus mission would follow on from this Europa mission.

    Or, assuming the SLS is successfully realised, could we simultaneously launch probes to both?

  • RobFlores February 5, 2015, 12:36

    I must admit those timelines look awfully long for a Europa Mission. It
    is in line NASA’s Conservative strategy. I think the biggest chance that NASA ever took, in robotic exploration, was the Viking landers. They were expensive and they did not prescisely know how rugged Mars surface was likely to be, it’s why the sent two of them.

    But on to Saturn,
    I think this is a golden opportunity for ESA to take up the banner of Saturn Space Exploration. They have a heavy launcher, They understand the Saturnian Moon system thanks to Cassini. Think about a what it would
    mean for prestige is ESA explored the Titan Seas and sampled the Plumes
    of Enceladous. You would not even need a submarine to explore the Titan
    seas. A Dirigible filled with a lifting gas, could go ‘Fishing’ with special probes. Maybe ESA can arrive at Saturn Before NASA arrives at Jupiter, as they don’t need to worry as much about the Radiation belts, and they are FORCED to use RTG’s in Saturn Space, simplifying things enormously.
    AND AS A BONUS, more advanced manufacturing methods available now, should lower the cost of constructing the main probe.

  • Lionel Ward February 5, 2015, 15:42

    @Ashley Baldwin
    Thanks for the reminder about the Falcon Heavy – and shall I never forget about it again! :) If mission planners aren’t currently factoring it into their roadmaps now, they certainly will be after it’s first successful launch

  • Joy February 5, 2015, 16:48

    Correcting a common misunderstanding regarding deep space missions:

    “a mission to this interesting moon (Enceladus – JS) will be much more expensive and take longer to develop than the currently proposed Europa mission ”

    Utterly, completely wrong!

    Where to begin? Yes Saturn is further out of Sol’s gravity well and missions take two years of additional cruise time post Jupiter flyby. However, there is no additional delta V required, the Jupiter gravity assist takes care of that. (As New Horizons has demonstrated, post Jupiter gravitational assist, any deep space destination is energetically attainable including the very interesting Neptune/Triton system.) The RTG and high gain antenna requirements are the same for Jupiter and Saturn (with an adjustment in data rate). The delta V required for orbital capture is the same for Jupiter and Saturn. Specifically, Galileo’s orbital insertion burn was 630 m/s while Cassini’s was 626 m/s.

    There is a huge developmental difference between Jupiter and Saturn orbital missions in that the need for extreme radiation hardening makes Jupiter missions a much more difficult and expensive engineering challenge. Saturn is a less demanding environment. As for the many years of supposed development of Europa Clipper hardware, none of that would be wasted. In fact, if Europa Clipper were launched to Jupiter at a time which was also a Saturn launch window, the probe could be redirected to Saturn/Enceladus at no additional cost other than the 2 year extension of cruise phase. As the geysers of Europa might be a very infrequent phenomenon, this would be the wiser move for astrobiology.

    Finally, in the early days of NASA, the wisdom of reusing common buses for spacecraft design was well understood. During a short period of years, the (more or less) assembly line Mariner series of probes visited Venus, Mars, and Mercury. Now every deep space probe must be engineered starting from scratch as a one off, the slowest and most expensive option. Not good for science, but an excellent program for the cost plus contractors and their subcontractors.

    Now imagine if Dan Goldin had ordered 3 Cassini buses to be produced at no increase in engineering cost (complete copies of rovers are routinely produced as the engineering and design is >> cost of fabrication). Cassini 2 and Cassini 3 might still be sitting in warehouses awaiting plutonium and launch vehicles (the Falcon 9 Heavy will be available soon), but at least we would have the option of someday soon launching ice giant missions to Uranus and Neptune with very low marginal cost.

    Space has never been about science at the management level. For JFK, it was primarily a political program. Since Nixon, NASA has been a self perpetuating welfare bureaucracy joined at the hip to the major contractors. Scientists are just along for the ride. The hugely expensive dead end ISS political/Boeing welfare program has produced no science of note, long duration microgravity missions had already been done on Mir. The tragically bad SLS currently in development had a mandate of retaining the low ISP (ICBM motors) solid fuel strap ons from the shuttle as well as the cryogenic H2-O2 core (higher ISP in vacuum completely wasted at sea level) to keep the shuttle contractors from the 1970s in business. NO OTHER REASON. Despite the fact that their previous design killed 14 astronauts. All of this to regain (after a half century!) the heavy lift capability of Arthur Rudolph’s beautifully designed Saturn V, which he first launched on his birthday in 1967. If the above doesn’t adequately demonstrate rampant incompetence and corruption … I am at a loss for words.

  • Enzo February 5, 2015, 17:17

    The reason I personally prefer Europa to Enceladus, apart from the reasons already mentioned (like the distance) is the fact that Enceladus’ activity seems to be local (i.e. it’s more like a lake than a global ocean). This makes me suspicious that it could be localized in time as well as space.
    In contrast, we know that Europa has a global ocean. The main questions there (inter-related) are :
    1) How thick is the ice ?
    2) Does the ocean interacts with the surface regularly ?
    The reason I think they are the main questions is because thin ice/ocean interaction has implications for extra energy reaching a potential biosphere from all the probable oxidizing compounds on the surface.
    Also thin ice/surface interaction => much easier to detect life.
    I’d be happy if a probe can answer these two questions. Clipper/JUICE should.

  • Andrew LePage February 5, 2015, 20:00

    @Joy February 5, 2015 at 16:48

    You are forgetting several key facts that make a Europa mission preferable to mission to Enceladus at this time:

    1) A Europa mission already has the advantage of two decades of detailed studies and analysis of the results from Galileo. Aside from the reluctance of Congress and various Administrations to commit the resources to a mission like Europa Clipper, it is ready to go NOW. Properly designing and developing a strategy to explore Enceldaus has only been under way for a handful of years with the study of Cassini’s findings still ongoing.

    2) A typical mission to Saturn has much longer flight times than a mission to Jupiter. While Cassini (and its predecessors like Voyager) were able to use Jupiter gravity assist trajectories to hasten their voyage to Saturn, trajectories to reach Saturn which minimize the orbit insertion delta-v requirements still have trip times of 6 to 10 years compared to 2 to 4 years to reach Jupiter on trajectories with comparable delta-V requirements (these flight times assume direct flights from Earth to target – additional Earth and/or Venus gravity assists (VEGA) can add years to these figures). These much longer flight times adds significantly to the burden of designing systems with the needed reliability/redundancy to ensure mission success.

    3) Even if we were to use a JGA trajectory to reach Saturn, launch opportunities that minimize flight times only occur for periods of several years every couple of decades. The last low-energy opportunities to use JGA to reach Saturn are in 2016 and 2017 – far too soon to realistically mount any sort of mission. After that, we have to wait until the next batch of low-energy opportunities which won’t start until around 2030.

    4) Without the JGA option available, there are only VEGA options available during the 2020 which add to the total flight time and have increased delta-v requirements to achieve orbit. Both of these factors lead to increased mission costs.

    Enceladus is certainly a target worthy but the planning for such a mission is no where near the maturity of a Europa mission and will be more expensive than a Europa mission. There is absolutely no good reason to pass up an opportunity to explore a perfectly good and scientifically interesting like Europa and instead wait another decade to mount a more expensive and longer mission to Europa. It makes more sense to go to Europa during the 2020s while planning a mission to Enceladus afterwards.

  • Andrew LePage February 5, 2015, 20:05

    Yikes, I should do a better job proofreading before I hit “Submit”. The last paragraph in my previous comment should read that there is absolutely no good reason to pass up an opportunity to explore a perfectly good and scientifically interesting like Europa and instead wait another decade to mount a more expensive and longer mission to Enceladus.

  • Tom February 6, 2015, 7:18

    The only limitation to these deep space expeditions is budgetary.
    $30 million dollars for a preliminary study for a proposed mission?
    This is about a little less than half of the budget for ISRO to send a modified telecom sat to Mars… launch included!
    It’s time for a lot of competition.
    The beauty of all this robot reconnaissance is… it’s one way.. no human lives being risked outside falling of a ground based dish or being blown up at a pad.

    This isn’t 1946, where the world leading rocket engineers all speak German, verstain?
    Let a highly innovative contractor build the probe after consulting at a public conference… maybe make the whole mission affordable for a cable company… see the results later.

    The way technology is pacing…National Geographic could fund something like this?

  • Wojciech J February 6, 2015, 12:36

    Joy February 4, 2015 at 15:34
    “Better yet, the pathway to a follow on Ceres lander is MUCH less problematic than a Europa lander. But Ceres will likely be neglected as it simply isn’t expensive enough to provide the job$ program that the industry demands.”

    Just to note that the Chinese Space Agency has proposed launching a Ceres sample retrieval mission in 2020s.Do note that this is a very early proposal as part of their extended mission program and not a full fledged mission concept/design. We will see what comes of it(likely in wake of Dawn’s discoveries)

  • andy February 9, 2015, 15:57

    Saw this one on the arXiv today: The pH of Enceladus’ ocean. The Enceladus ocean is predicted to be highly alkaline, which contrasts with the traditional acidic picture of the Europa ocean, though as noted in the paper the latter may need some revision. Mike Brown’s blog about Europan salts is worth a look, part 1 is here, follow the links through to 2 and 3 – note also the point that Galileo didn’t get good enough spectra of the Europan surface to determine what salts were there, and there is now better spectral mapping from the Keck telescope than we got from Galileo.

    Back to the Enceladus paper, there is also the point that the ocean floor conditions are likely to be very different also (Europa is predicted to be basaltic with active volcanism, Enceladus is not), which has implications for the chemical evolution of the oceans. Enceladus also lacks a nearby Io dumping sulphur over large parts of its surface. Point is, they are different worlds with different chemistry going on, so you may want to send different instruments along on the mission depending on destination.

  • Robert Clark February 12, 2015, 11:40

    Doing some rough calculations it should be doable to do an actual lander mission to Europa launched by a Falcon Heavy. This would of course be a much cheaper launch cost than using the SLS.

    The in-space stages would use already existing stages. This would significantly cut down on development costs. Centaur(s) would provide the propulsion for the Jupiter transfer insertion to escape Earth orbit. For the propulsion on reaching Jupiter, because of the long flight time, we’ll use hypergolics which won’t have a boiloff problem. Various small hypergolic stages already exist that could be used.

    I like the suggestion of U. of Ariz. professor Christopher Impey that such a mission could be mounted by private funding:

    SUNDAY, FEBRUARY 8, 2015
    Let’s Send a Private Mission to Europa, Expert Says.
    http://www.astrowatch.net/2015/02/lets-send-private-mission-to-europa.html

    Using the Falcon Heavy and existing in-space stages, the total launch cost might be in the $200 million range. And using a small Mars Pathfinder style lander the spacecraft development would be well less than $100 million, especially if fully privately funded.

    Bob Clark

  • ljk February 13, 2015, 15:20

    The gift of a Europa mission may have a cost

    NASA’s 2016 budget proposal, released last week, included plans to formally start work on a project to send a mission to Jupiter’s moon Europa. Jeff Foust reports that while this is good news for mission advocates, that decision could have a funding catch.

    Monday, February 9, 2015

    http://www.thespacereview.com/article/2691/1

  • ljk March 12, 2015, 10:31

    Europa Clipper concept team aims for launch in 2022

    Posted on March 10, 2015

    by Stephen Clark

    With a commitment from the Obama administration finally in hand after more than a decade of studies and concept papers, NASA expects to give the green light this year for development of a robotic probe to Jupiter’s icy moon Europa that could launch as soon as 2022.

    “It’s a tremendous opportunity for us to be able to look at a potentially habitable world around a giant planet,” said Jim Green, director of NASA’s planetary science division.

    One concept led by NASA’s Jet Propulsion Laboratory and the Johns Hopkins University Applied Physics Laboratory is the favorite to win NASA’s backing.

    The Europa Clipper mission came out of a multi-year study to slash the cost of a mission to study the enigmatic moon, eventually settling on a projected price tag near $2 billion — excluding launch costs — less than half the estimated cost of a Europa probe published in a decadal survey report by the National Research Council in 2011.

    Scientists and engineers found savings in switching the probe from a nuclear-powered design to a solar power source and crafting a mission to fly by Europa dozens of times instead of entering orbit around the icy moon.

    Officials say the Europa Clipper concept may need some tweaks, but it gives NASA a good starting point for development expected to start after it wins programmatic approval in a milestone expected as soon as mid-2015.

    The milestone, known as Key Decision Point A (KDP-A) in NASA’s parlance, will mark the start of full-scale development of the Europa probe. Decisions on scientific instrumentation, mission design, a launch vehicle and launch date, and international partnerships will follow.

    “Europa Clipper has had quite an important evolution,” Green said in a Feb. 19 meeting of NASA’s Outer Planets Assessment Group. “It is a proof of concept that says we can do it, and it’s not a $4 billion mission as we studied and discussed at the decadal, so it has made major progress.”

    Full article here:

    http://spaceflightnow.com/2015/03/10/europa-clipper-concept-team-aims-for-launch-in-2022/