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Old 01-20-2014, 02:39 AM   #16
Unstung
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I think the applications of the SLS are interesting like the Apollo Applications Program. One particularly enticing idea is Skylab II, a cheap alternative for a space station at L2.

However, launching the Europa Clipper on the SLS is much more expensive, but cuts down the 7 year transit time from using VEEGA (Venus Earth Earth Gravity Assist) to two years. There are some other benefits to using the SLS, such as being able to deploy nanosatellites around Europa and not having to make the spacecraft survive being close to the sun. If the Falcon Heavy can be used instead, it would be much more cost effective. The SLS may speed up a fancy NASA-style Mars sample return, but there are no formal plans for returning samples from Europa.

A sample return mission from Europa's surface, or just a lander, may be fruitless due to the high energy radiation environment around the moon. Also, Europa's surface must be characterized better first to choose a good landing site, something that cannot be done without a Flagship precursor mission with instruments ranging from a ground-penetrating radar to a reconnaissance imager. A more simple spacecraft could return potentially more valuable samples from Europa's recently discovered geysers using an aerogel like Stardust. It may require a smaller launch vehicle and could fit within a New Frontiers (or smaller) budget. NASA cannot afford another huge Flagship mission.

The Viking spacecraft were launched before NASA knew how and where to land on Mars.

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Old 01-29-2014, 07:10 PM   #17
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Europa mission idea.. what do you think?
- You make a very powerful laser projector on earth, the moon or earth orbit,
- put a satellite in Europa orbit with lenses and a good camera,
- fire laser from here to the satellite
- focus it onto a spot on Europa's surface to cut into the ice
- when through to the other side drop a probe down the tunnel
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Old 03-05-2014, 01:31 PM   #18
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Default NASA Eyes Ambitious Mission to Jupiter's Icy Moon Europa by 2025

NASA hopes to launch a mission to the Jupiter moon Europa, perhaps the solar system's best bet to host alien life, a decade or so from now, officials announced Tuesday (March 4).
The White House's 2015 federal budget request, which was released Tuesday, allocates $15 million to help develop a mission to Europa, which harbors a potentially life-supporting ocean of liquid water beneath its icy shell.
"Europa is a very challenging mission operating in a really high radiation environment, and there's lots to do to prepare for it," NASA chief financial officer Beth Robinson told reporters Tuesday. "We're looking for a launch some time in the mid-2020s." [Photos: Europa, Mysterious Icy Moon of Jupiter]



The $15 million — which represents a tiny fraction of the $17.5 billion allocated to the space agency in the 2015 request — would fund very early "pre-formulation" work for a potential Europa mission, Robinson added.
"I know people have asked about the total size [of the possible mission], and we're frankly just not sure at this point," she said, adding that agency officials will reach out to the scientific community to help map out the mission.

Though the 2015 proposal marks the first time Europa was included in a federal budget request, NASA has received funding to study a possible mission to the 1,900-mile-wide (3,100 kilometers) moon in the past. Congress allocated the space agency a total of $155 million toward this end over the last two years.

Though statements by Robinson and other NASA officials suggest that the Europa mission space is wide open at this point, the best candidate to get off the ground in 2025 or so may be a concept called the Europa Clipper.
NASA researchers have been developing the Europa Clipper idea for years. The probe would orbit Jupiter but make dozens of flybys of Europa, using a variety of science instruments to study the moon's ice shell and subsurface ocean.

The Europa Clipper could conceivably cruise through the plumes of water vapor erupting from the moon's south pole — intriguing features that were discovered late last year and have helped build momentum for a Europa mission, since they offer a possible way to sample the ocean from afar.
It would probably cost about $2 billion to get the Europa Clipper off the ground, officials have estimated. That's a pretty high price tag in these tough fiscal times, so some rethinking may be required to take the Clipper — or something like it — from concept to reality.

The Europa Clipper "is what we would call a flagship, and right now the budget horizon is such that we're deferring that kind of mission until later in the decade," Jim Green, head of NASA's planetary science division, said in December at the annual fall meeting of the American Geophysical Union in San Francisco.

Source: Space.com

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Old 03-05-2014, 05:59 PM   #19
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This has been a long time coming!

I had the privilege of peeking at the development cycle of one of the potential instruments back in 1999. I wonder if it will still be used...

Quote:
Once the technology has been developed and demonstrated to work at depths of 4,000 meters (13,200 feet), the probe's external shell will be modified for use in sub-glacial lakes like Lake Vostok, an ancient freshwater lake that appears to extend about that deep beneath Antarctic's surface. The design may also become a prototype for a probe that could penetrate Mars' icy polar caps and search for microbial life, or explore a liquid ocean thought to lie 7 kilometers to 8 kilometers (about 4 miles to 5 miles) below the icy surface of Europa.
http://www.jpl.nasa.gov/news/releases/99/monterey.html

Here's the project I worked on back in the day when I was just a youngin' coming out of high school and scored an internship at JPL. I worked directly under Dr. Lane, Lloyd French, and his wife Gindi French.

In fact, I built the little portable crane they used to conduct this test at Monterey Bay mentioned in the article.

---------- Post added at 09:59 AM ---------- Previous post was at 09:52 AM ----------

Back then, these thermal burrowing probes were the main contender for delivery. looks like they are still in the running.

http://www.astrobio.net/exclusive/34...opa-acutes-ice

It appears the submersible robot has been given the ax though
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Old 03-06-2014, 12:14 AM   #20
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The similar threads have been merged, I don't think the news adds much to what's already known. It's hard to cover a topic like this on a regular basis when there simply isn't much happening. A mission to Europa is still a long way off. I was hoping for construction to start on the spacecraft in 2015, but the budget proposal falls far short.

I've covered a potential $1 billion dollar Europa mission earlier on in this thread, and NASA is now more officially supporting that idea:
The Planetary Society: "NASA Wants to Explore Europa On the Cheap"
The science would be affected with a cheaper mission, which hasn't been addressed. The $2 billion Europa Clipper can cover about 80% of the science compared to the canceled $4.7 billion Jupiter Europa Orbiter. However, attempting to reduce the mission's funds further may dramatically affect its capabilities. $2 billion looks like a sweet spot between cost and science. Any more and there's very diminishing returns, while much less significantly descopes the mission. A larger portion of a smaller budget would be spent on merely getting the spacecraft to Europa and keeping it alive. A smaller spacecraft can only carry so many instruments. It still requires radiation shielding, RTGs, antennas, reaction wheels, and other necessary systems. The number of flybys may be reduced and thus the amount of surface studied will be decreased.

This link shows what systems Cassini requires to function no matter how much was spent on the mission. Scientific instruments are a small part of its mass, like probably any spacecraft.

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Old 03-06-2014, 06:05 AM   #21
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In my humble opinion, I think Cassini is one of the best successes of science (like Huygens probe and Voyager). And if I were to choose to route the money between Cassini and Europe Clipper, I would bet the Cassini probe and the SLS.

The satellites Europa and Titan always fascinated me, would be very interesting also send another probe (more advanced to Huygens) to Titan.
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Old 03-19-2014, 08:50 AM   #22
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Below is an excellent summary of the path towards the current Europa mission proposal for those who want to become informed yet not read every minor update.

Scientific American: "Europa’s Water Geysers Entice Scientists to Send a Probe—but Can NASA Do It on the Cheap?"

The entire article:

Quote:
The more we learn about Europa, the greater its allure. Galileo Galilei discovered Jupiter’s four largest moons in 1610, and in the intervening centuries Europa, the smallest of them, has revealed itself as a likely harbor for liquid water—and maybe even life. Last week NASA took tentative steps toward sending a robotic mission there—a goal long lauded by planetary scientists. But exploring Europa presents some serious technological, financial and political challenges.

For the last few year's NASA's planetary science budget has seen a major crunch, and the lion's share of its remaining funds have gone to Mars missions. Despite the high priority given to Europa exploration in the U.S. National Research Council’s last decadal survey, an overview of the most pressing goals in planetary science, NASA has not requested any money for planning a Europa mission in recent years. Nevertheless, Europa fans in Congress have allocated funding for it, granting $43 million in 2013 and $80 million in 2014. Proponents of the mission were therefore heartened last week to see the White House's 2015 NASA budget request include a line item of $15 million for Europa exploration planning, although the amount is far less than many would hope for. "If nothing else, we're excited to see NASA and the White House put it into budget lines and acknowledge it’s an important destination," says Casey Dreier, director of advocacy at the Planetary Society, a nonprofit organization devoted to solar system science and exploration. The size of the request—$15 million out of NASA's total budget request of $17.5 billion—is "a very small amount of money" but the symbolism of the move is significant, he says. "The fact that it's in there is a big, big shift, and I think a big part of that is the discovery of those plumes."

In December scientists announced that the Hubble Space Telescope had spotted geysers of water vapor shooting from Europa's surface, most likely originating from a liquid water ocean thought to exist under the moon's icy surface. This theorized ocean has long been the focal point for hopes that Europa could host microbial life, but scientists assumed that a lander would be required to drill down into the ice to reach the liquid water for sampling. The geysers may make the water more accessible, however. "If that’s the case, maybe we don’t have to go to the ocean—the ocean will come to us," says astrobiologist Chris McKay of NASA Ames Research Center at Moffett Field, Calif.

The discovery of the geysers may have been the push that Europa needed to attain must-explore status. "The big question that ultimately drives us to study Europa is 'Does life exist there?'" says Kurt Retherford of the Southwest Research Institute (SwRI) in San Antonio, Texas, one of the co-discoverers of the water vapor plumes. "I think most of us had imagined that two or three large and expensive Europa missions would be needed before we find a clear answer to this compelling question, including future landers and deep-drilling devices."

Sending a probe to fly through the geysers would be cheaper but Retherford cautions against designing a Europa mission completely around the plumes. For one thing, the water vapor appears to be time-variable, and scientists cannot yet predict when the plumes will be active. "Until we are able to more firmly confirm our discovery of Europa’s water vapor plumes with additional observations in the next few years, it would seem inappropriate to focus a mission to exclusively study geysers at this time," Retherford says.

Europa presents other challenges as well: The moon is situated within Jupiter's intense radiation field, which would bombard spacecraft with radiation that could damage sensitive electronics. The best solution is to encase a Europa probe in thick shielding, which would increase its weight and thus the cost to launch it. The Jovian system is also far from Earth, probably at least a six-year journey, which adds to the time and expense of the total mission. "The Europa program is a complicated, expensive, step-by-step process because of these difficulties," McKay says.

Researchers have been working on Europa mission concepts for years. A proposed NASA mission called the Europa Orbiter, estimated to cost $4.7 billion, was canceled in 2002. Following that disappointment, scientists devised a reduced-cost plan for around $2 billion called the Europa Clipper, which would orbit Jupiter and make repeated low-altitude flybys of Europa. The Europa funding allocated to NASA in recent years has gone toward furthering that plan. "The Clipper concept is very mature," Dreier says. "They could basically start today on that mission."

After the NASA budget announcement last week, however, agency chief, Charles Bolden, said NASA was looking to spend less than $1 billion total on a Europa mission. That would put the spacecraft in a class of missions called "New Frontiers," a less expensive category than its bigger "Flagship missions." NASA plans to issue a "request for information" to solicit ideas from scientists on what type of Europa mission could be done for under $1 billion. But some worry that price point puts most major science goals out of reach. "No one has really thought much about what you can do with that minimal budget," Dreier adds.

Scientists' wish list for a Europa mission includes characterizing the chemistry of its subsurface ocean, learning how large the ocean is and determining the thickness of the ice shell that encloses it. "Measuring the composition of Europa's ice-water shell is important," says Lorenz Roth of the SwRI, lead author of the paper announcing the water geyser discovery. "Flying through plumes from active outgassing and measuring their composition" is another priority, Roth adds. Whether a New Frontiers mission can accomplish all those goals remains to be seen.

Europa has several champions in Congress. Texas Rep. John Culberson (R), a member of the House Appropriations Committee, has led the charge to insert Europa funding into the agency's budget. Culberson is next in line to become chairman of the subcommittee responsible for NASA's budget, where he could exert considerable influence to make the mission fly. That is comforting news to Europa proponents, who know it will take a cosmic alignment of political goodwill, money and technical know-how to reach Jupiter's enigmatic moon. If it happens, however, the payoff could be nothing less than finding life beyond Earth.
I've underestimated the positivity that other supporters see in having official White House and NASA support for the mission. Unfortunately a mid-2020s launch is a few years behind what can be achieved now. Europa Clipper is much more realistic than JIMO and JEO with a cost-effective design and a payload that has a high technology readiness level (page 24)*. With the discovery of geysers, some extra time may actually be beneficial so the payload can be improved to study them, but all this science seems impossible to do as a New Frontiers budget.

*latest version of the Europa Clipper summary: http://www.lpi.usra.edu/opag/jul2013...er_Summary.pdf
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Old 07-23-2014, 01:16 PM   #23
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There has been a relatively significant update a week ago regarding the future of a mission to Europa. NASA is now soliciting proposals until October 17 for the scientific instrumentation aboard such a mission. Up to 20 proposals will be selected in April 2015 for further study. Among the previous goals for a Europa mission as outlined in the Planetary Decadal Survey, the ability for a spacecraft to study possible Europan plumes has been added. The $2 billion Europa Clipper will already be able to study any plumes with its mass spectrometer and thermal imager. Meanwhile, NASA is assessing a $1 billion alternative that still appears too frugal to complete enough desired objectives.

NASA: "NASA Seeks Proposals for Europa Mission Science Instruments"
Quote:
[...]

The AO calls for proposals compatible with a spacecraft that would either orbit or perform multiple flybys of Europa. Spacecraft instruments will be used to conduct high priority scientific investigations addressing the science goals for the moon's exploration outlined in the National Resource Council’s (NRC) Planetary Decadal Survey.

The Decadal Survey deemed a mission to Europa among the highest priority scientific pursuits for NASA. It listed five key science objectives in priority order that are necessary to improve our understanding of the potentially habitable moon:
  • Characterize the extent of the ocean and its relation to the deeper interior
  • Characterize the ice shell and any subsurface water, including their heterogeneity, and the nature of surface-ice-ocean exchange
  • Determine global surface, compositions and chemistry, especially as related to habitability
  • Understand the formation of surface features, including sites of recent or current activity, identify and characterize candidate sites for future detailed exploration
  • Understand Europa’s space environment and interaction with the magnetosphere.

[...]
Future Planetary Exploration: "Mars and Europa: Contrasts in Mission Planning"
Quote:
[...]

Usually when NASA requests instrument proposals, it has a solid mission concept in mind. For this call, NASA said that the Europa mission might be an orbiter or might be a multi-flyby spacecraft. The request document was vague as to the budget for instruments and just said that past studies assumed it would likely be around 15% of the total mission cost. While many instruments by their nature have modest costs, some could be quite costly and it might help proposers to know whether the total instrument budget is closer to $150M (for the $1B total mission cost NASA would like) or to $300M (for the ~$2B that past studies have said is needed to achieve all the high priority scientific goals).

For some instruments, proposers will have to bet that NASA either selects a multi-flyby spacecraft or an orbiter. For example, measuring Europan tides would help pin down the depth of the ice covering the ocean. A laser altimeter could accurately measure the tides, but it requires an orbiting platform to pin down the size of the tides. If NASA goes with a flyby spacecraft, any group that proposed an altimeter is likely to be out of luck.

[...]

While NASA’s management decides the scope of a Europa mission, engineers at JPL continue to refine the design of the current leading concept, the Europa Clipper that comes with an estimated cost of $2.1B. The current concept would have the Clipper spacecraft make 45 dashes through the radiation fields surrounding Europa for close up looks at the surface and interior. Building a spacecraft and instruments that can survive that radiation exposure is one of the factors that has driven the cost well above the $1B NASA’s senior managers would like to see.

A presentation made to the science team also provides more insight as to why a large number of encounters are required to study Europa. The science team has carefully justified what measurements are needed at Europa to understand this world and to enable planning for a lander that would follow the Europa Clipper.

As an example, the science team has stated a requirement that the composition of 70% of the surface be mapped at resolutions of less than 10 kilometers by an instrument known as a short-wave infrared spectrometer. With 45 encounters, this goal would be just missed with 68% of the surface mapped. (Thirty flybys would map 50% at this resolution or better.) Similarly, mapping 70% of the surface with an imaging camera at resolutions of 1 kilometer or better would require 38 flybys. A global distribution of flybys to study the structure of the ice and ocean beneath the surface with an ice penetrating radar would not be met until 43 flybys.

If the radiation belt did not exist, the next stage to exploring Europa would be to orbit it instead of frantically gathering data during numerous brief flybys. (Europe, for example, will send the JUICE spacecraft to orbit Europa’s sister moon Ganymede, but that moon lies outside the harshest portions of the radiation belt.) JPL’s studies suggest that a Europa orbiter would cost about the same as the Europa Clipper, but its lifetime would be so short that the Clipper with its many flybys would better study this moon.

[...]

The launch is still likely to occur in the early to mid-2020s.

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Old 10-11-2014, 03:25 PM   #24
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If one looks at the webpage for Europa Clipper on JPL's newly redesigned website, they may notice something different: the spacecraft's radioisotope thermoelectric generators are gone. The design team recently chose to use solar panels over a plutonium power source.

Solar panels are cheaper to implement on a spacecraft than RTGs. Launching a solar power generator into space is less controversial than launching a nuclear one. NASA's supply of plutonium is precious and limited, so being able to conserve it whenever possible is a bonus. Nonetheless, there are drawbacks to solar power.

A solar powered space probe will have limited time to operate when in shadow or pointed away from the sun depending on its batteries. Adding increased capacity batteries and the large solar arrays a spacecraft needs at Jupiter requires more mass than encapsulated plutonium pellets. This may necessitate a larger launch vehicle than the Atlas V, but the mission is not committed to a specific rocket yet.

Some members of Congress are interested in launching Europa Clipper on the SLS to keep the vehicle active. Increasing the frequency of launches will reduce the rocket's cost per launch because the infrastructure is already in place and hardly used. There are other benefits of a direct launch to Jupiter such as reducing transit and hibernation time which keeps the spacecraft and investigators younger, requiring fewer years of costly support. Europa Clipper would not need to dive towards Venus and endure the increased solar radiation either.

While a faster transit will reduce operation costs, the SLS is still very expensive launcher. The heavy lift launch vehicle will definitely cost more than any savings it creates. This makes the Falcon Heavy a potentially very lucrative launcher for Europa Clipper. Having extra payload mass also opens up revolutionary possibilities for planetary exploration.


SpaceNews: "Europa Clipper Opts for Solar Power over Nuclear"
Quote:
Designers of a proposed NASA mission to study the icy and potentially habitable Jupiter moon of Europa have decided to use solar panels rather than a nuclear power source for the spacecraft, while keeping spacecraft’s launch options open.

In an Oct. 3 presentation at the 65th International Astronautical Congress here, Europa Clipper deputy project manager Thomas Magner of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, said that using large solar panels for the mission was both technically viable and less expensive than a radioisotope thermoelectric generator (RTG).

“For the last two years, we did extensive risk reduction work looking at whether solar is feasible,” Magner said. “We found that solar works fine, so our final decision about two months ago was to go to solar.”

Those tests included subjecting solar cells to a range of temperatures and radiation conditions the spacecraft would experience during the mission. Engineers also examined whether the large solar panels, with an area of 50 square meters, would cause jitter that would adversely affect the spacecraft’s scientific instruments.

[...]

One last thing: cubesats. They can enhance any planetary mission and may fit within Europa Clipper's launch vehicle.

JPL: "JPL Selects Europa CubeSat Proposals for Study"
Quote:
NASA's Jet Propulsion Laboratory in Pasadena, California, has chosen proposals from 10 universities to study CubeSat concepts that could enhance a Europa mission concept currently under study by NASA. The CubeSat concepts will be incorporated into a JPL study describing how small probes could be carried as auxiliary payloads. The CubeSats would then be released in the Jovian system to make measurements and enhance our understanding of Jupiter's moon Europa.

[...]
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Old 01-11-2015, 10:03 AM   #25
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In the spirit of Galactic Penguin, I have changed the titles of the Europa Clipper and JUICE mission threads to something more creative.

Now, about a year ago, evidence of geysers coming from Europa was discovered by Hubble. Unfortunately, recently analyzed data from the Cassini Jupiter Millennium Flyby shows that if Europa has geysers, they erupt only on occasion and may be less powerful than thought. This has implications for trying to sample Europa's ocean without landing on the surface and how much interaction the ocean has with the surface.

JPL: "Signs of Europa Plumes Remain Elusive in Search of Cassini Data"
Quote:
A fresh look at data collected by NASA's Cassini spacecraft during its 2001 flyby of Jupiter shows that Europa's tenuous atmosphere is even thinner than previously thought and also suggests that the thin, hot gas around the moon does not show evidence of plume activity occurring at the time of the flyby. The new research provides a snapshot of Europa's state of activity at that time, and suggests that if there is plume activity, it is likely intermittent.

The Europa results are being presented today at the American Geophysical Union fall meeting in San Francisco and published in the Astrophysical Journal. Europa is considered one of the most exciting destinations in the solar system for future exploration because it shows strong indications of having an ocean beneath its icy crust.

Members of Cassini's ultraviolet imaging spectrograph (UVIS) team analyzed data collected by their instrument during the brief time it observed Europa in 2001, as Cassini sped through the Jupiter system en route to Saturn. The observations show that most of the hot, excited gas, or plasma, around Europa originates not from the moon itself, but from volcanoes on the nearby moon Io. In fact, from their data, the researchers calculated that Europa contributes 40 times less oxygen than previously thought to its surrounding environment.

"Our work shows that researchers have been overestimating the density of Europa's atmosphere by quite a bit," said Don Shemansky, a Cassini UVIS team member with Space Environment Technologies in Pasadena, California, who led the study. The team found that the moon's tenuous atmosphere, which was already thought to be millions of times thinner than Earth's atmosphere, is actually about 100 times less dense than those previous estimates.

A downward revision in the amount of oxygen Europa pumps into the environment around Jupiter would make it less likely that the moon is regularly venting plumes of water vapor high into orbit, especially at the time the data was acquired.

Scientists would expect that ongoing plume activity at Europa, as Cassini has observed at Saturn's moon Enceladus, would inject large amounts of water vapor into the area around Europa's orbit if the plumes were large enough, but that is not what UVIS observed.

"We found no evidence for water near Europa, even though we have readily detected it as it erupts in the plumes of Enceladus," said Larry Esposito, UVIS team lead at the University of Colorado at Boulder.

"It is certainly still possible that plume activity occurs, but that it is infrequent or the plumes are smaller than we see at Enceladus," said Amanda Hendrix, a Cassini UVIS team member with the Planetary Science Institute in Pasadena, who co-authored the new study. "If eruptive activity was occurring at the time of Cassini's flyby, it was at a level too low to be detectable by UVIS."

[...]
On the bright side, also in late 2014, JPL released an improved mosaic of Europa with realistic color:

I have just updated the thread on the JUICE mission with information about the spacecraft's role in European exploration. In the articled cited in my previous post, Van Kane also describes some recent progress with the Europa Clipper mission, although he has a more skeptical attitude than The Planetary Society towards whether Europa Clipper will fly.
Quote:
Breaking news: I listened in on a presentation by Jim Green, head of NASA’s Planetary Science Division at this week’s Small Bodies Assessment Group. Dr. Green says that NASA hopes that it will be able to use the $100M Congress added to NASA’s budget for a Europa mission to enable a New Start for the Europa Clipper program. This is the term for when a mission goes from the wish list to an approved program. This is the first that I had heard that NASA’s management was looking to commit to a Europa mission. This isn’t a done deal: the President’s Office of Budget and Management (OMB) must also approve a new start, and in the past they have not been. (Congress must also approve a new start, but the substantial funding it has already supplied suggests that it would.) We will see with the release of the Fiscal Year 2016 budget request whether OMB’s stance has changed. IF a new start is given, then the important questions will be the total budget for the mission and when launch is planned (which might be in the mid-2020’s).
There have been no updates in this thread about where exactly that $100 million came from, so you can read about it in "Here's How Planetary Science Will Spend Its $1.44 Billion in 2015".
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Old 02-05-2015, 11:08 PM   #26
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The Planetary Society: "It's Official: We're On the Way to Europa"

Bad Astronomy: "NASA Has Its Sights Set on Europa"

SPACE.com: "NASA Europa Mission Gets White House Approval"

Future Planetary Exploration: "2016 Budget: Great Policy Document and A Much Better Budget"


Summary: The White House has given a mission to Europa a new start and $30 million, the most it has proposed for such a mission. Now the mission can go from being a concept to Phase A, an "actual mission". The worst that can now happen to the mission is cancellation, but this is the farthest along such a mission has ever been. This is more official than the proposed $16 billion Jupiter Icy Moons Orbiter and the $4.7 billion Jupiter Europa Orbiter. At the current rate of funding, NASA's Europa spacecraft will launch in the next decade, with significant progress being made on the vehicle at the end of this decade. It's a long wait, but it's happening.
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Old 02-06-2015, 11:23 PM   #27
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This mission seems really expensive, with limited objectives and too far in the distance to excite It would better to send something cheaper and quick, to just have a visual reconnaissance of the surface (by crashing it admittedly) to see if a lander is feasible on Europa. (We have no idea how rugged the terrain is) Then a proper mission can designed with a lander. 2 billion is
a lot of money even for an extended look see of just Europa. Yeah , and
good luck with those Solar Panels around Jupiter Space.

If ESA had some gumption, it could get to Saturn faster and with a
more interesting missions with Titan a lander and a close in reconnaissance of
Enceladous.
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Old 02-07-2015, 02:03 AM   #28
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The Europa Clipper's primary goal is not reconnaissance. In fact, a recon camera is not included in the baseline science instruments. The mission is designed to assess the habitability of Europa's ocean, so minute surface details are not that important. The habitability of the moon has never been assessed, therefore there is much speculation about conditions underneath the surface and little data.

The Europa Clipper will be able to study the entire globe of Europa over dozens of flybys and answer whether or not the moon is a good place to look for life. It would also give scientists and engineers an idea of how hard it would be to search for life by assessing the ice shell's thickness and geologic activity among several other objectives. A more expensive $2.5 billion rover is already studying a small region of Mars to assess that area's past habitability.

The environment surrounding Europa is very harsh and difficult to reach, so $2 billion for a mission this capable is a bargain. Just to reach Europa to get some high resolution photos of a few sites will cost at least as much as a Discovery mission (~$500 million). Deliberately crashing a spacecraft into Europa will increase costs due to planetary protection, and that has an even lower chance of finding a suitable landing site.

Landing on Europa is undoubtedly very difficult and it is simply not known where is a safe landing site that is also ideal to search for biology. Only the Europa Clipper with a reconnaissance camera can find a proper site for just $2 billion. The previous proposal NASA was considering that would have similar capabilities was projected cost $4.7 billion. A lander will almost certainly be more expensive than $2 billion because it has to endure harsher conditions and, well, land. It is better ensure a surface mission will be successful and fruitful the first time than guess with limited coverage of the moon.

The easiest claim to rebuttal is that solar panels will limit the mission. If the scientists and engineers thought this, they would not have transitioned from using plutonium to photons. The next two missions to the Jupiter system are already using solar (Juno and JUICE), so that indicates that using solar panels have become feasible at 5 AU.

It is better to save RTGs for missions that need them, like the Titan boat and Enceladus geyser sample return. Both of those missions are projected to fit within a Discovery budget because they have a very limited scope. Each one has far fewer instruments than a flagship mission and are not a habitability utility knife like the Europa Clipper. It is possible for a flagship Europa mission to coexist with Saturn missions as long as Mars isn't the preference in the Planetary Science budget.

Last edited by Unstung; 02-08-2015 at 03:14 AM.
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Old 02-07-2015, 02:52 AM   #29
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 he easiest claim to rebuttal is that solar panels will limit the mission. If the scientists and engineers thought this, they would not have transitioned from using plutonium to photons. The next two missions to the Jupiter system are already using solar (Juno and JUICE), so that indicates that using solar panels have become feasible at 5 AU.
Don't forget Rosetta. Not a Jupiter mission, but it has gone out almost as far, and its solar cell technologies will be implemented in JUICE.

A note on Clipper's change to solar arrays instead of the previously baselined RTGs, specifically I think that another reason it was switched to solar power is/was because the US is no longer producing a domestic supply of plutonium, and a mission such as Clipper would've consumed a large portion of the existing stockpile.

As such it was/is highly desirable for Clipper to have switched to solar power, since that is indeed feasible at that distance.
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Old 02-07-2015, 09:03 AM   #30
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 A note on Clipper's change to solar arrays instead of the previously baselined RTGs, specifically I think that another reason it was switched to solar power is/was because the US is no longer producing a domestic supply of plutonium, and a mission such as Clipper would've consumed a large portion of the existing stockpile.

As such it was/is highly desirable for Clipper to have switched to solar power, since that is indeed feasible at that distance.
The DoE is finally restarting the production of plutonium, funded by NASA. The stockpile of plutonium will start to increase slowly in the coming years, but if the Clipper mission flies with MMRTGs, it would use about all of NASA's present plutonium supply. That is four or five RTGs. Before the apparent commitment to solar power, the Europa Clipper team was looking to reduce the number of required RTGs to four. It is disappointing that funds for research on the more efficient ASRG dried up as Planetary Science's budget was significantly cut.

I already mentioned the plutonium issue in two consecutive posts previously.
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