Tag Archives: Jonathan Amos

Robots on Enceladus!

In the last two decades, we have established that this solar system is awash in water, albeit mostly dirty ice. That’s good news for our 98%-water species, at least in the very long term. Whatever else, we shouldn’t die out of thirst.

Even more interesting are the “ocean worlds“, icy moons of Neptune and Saturn (and, who knows, outer planets such as Pluto and Uranus), which probably have a liquid ocean underneath a thick crust of ice.

As I have noted earlier, ESA and NASA are gearing up to explore these worlds, because we just have to.  A prime target is the large moon Europa, which has a fissured icy crust and, most likely, a watery ocean below.

This week Waite, J. Hunter and colleagues report on yet another moon, Enceladus, which also has an icy crust ovre a liquid ocean. Enceladus also has active volcanoes !spewing water vapor. Whoa!

Enceladus is also notable because the Cassini spacecraft actually visited and swooped through one of the volcanic plumes to take a sample.

As Waite et al report, this sample contains water with traces of several other species, including H2. (See [2] for the details of this non-trivial measurement, a billion KM from home.) The researchers are particularly interest in H2, because they theorize that it is generated by “ongoing hydrothermal reactions of rock containing reduced minerals and organic materials.” They also calculate that this indicates “thermodynamic disequilibrium that favors the formation of methane from CO2 in Enceladus’ ocean “ (p. 155)

The thermodynamics and Hydrogen are both highly favorable for microbes, so these findings suggest that the ocean is “habitable”. This makes Enceladus a tempting target for a landing mission.

“We’re pretty darn sure that the internal ocean of Enceladus is habitable and we need to go back and investigate it further,” said Cassini scientist Dr Hunter Waite from the Southwest Research Institute in San Antonio, Texas.”  (quoted in [1])

So now we have at least two high priority “ocean worlds” that we should must visit.

The good news is that the gear being developed will work for missions to either or both Enceladus or Europa.

It is difficult to be optimistic about the prospects for government funding for such missions (unless someone’s family can make a bundle off the “deal”).

But, why aren’t the Silicon Valley hobbyists all over this stuff? This is way more interesting than sending rich tourists into low Earth orbit, and probably cheaper, too.

So let’s all raise a glass to my new favorite, “Robots on Enceladus!”

Suck on that, Europa.


  1. Jonathan Amos, Saturn moon ‘able to support life’. BBC News – Science & Environment.April 13 2017, http://www.bbc.co.uk/news/science-environment-39592059
  2. J. Hunter, Waite, Christopher R. Glein, Rebecca S. Perryman, Ben D. Teolis, Brian A. Magee, Greg Miller, Jacob Grimes, Mark E. Perry, Kelly E. Miller, Alexis Bouquet, Jonathan I. Lunine, Tim Brockwell, and Scott J. Bolton, Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes. Science, 356 (6334):155-159, 2017. http://science.sciencemag.org/content/356/6334/155

 

Space Saturday

Evidence of Water Volcanoes on Europa

While waiting for pictures from Rosetta’s last dive, and also waiting for Juno’s next pass at Jupiter, we see more indications of how cool Jupiter’s moon Europa is.

William Sparks and colleagues (including Melissa McGrath of The SETI Institute, no relation so far as I know) published a study using the Hubble Space Telescope to detect evidence of water plumes shooting out from Europa [1].

Such plumes of water have been observed at Saturn’s moon Enceladus, and there is strong reason to think that Europa has a liquid water ocean under the frozen surface. So this would not be unbelievable.

The new study stretches the limits of the Hubble, identifying smudges that could be water plumes. Other spectroscopic studies have detected Hydrogen and Oxygen in these regions, supporting the notion that there might be water there. Suggestive, but hardly conclusive or very detailed evidence.

The possibility of water plumes high above the surface is particularly interesting because Europa’s ocean is one of the places in our solar system that might support life. A mission to that ocean will be really, really difficult, but maybe we can orbit or land on the surface to sample from these plumes. This could tell us quite a bit about what is down below, even if we can’t visit yet.

Both NASA an ESA are planning possible missions to fly by Europa in the next decade. Clearly, investigating water jets, if they can be found, will be a high priority.

Cool!


  1. W. B. Sparks, K. P. Hand, M. A. McGrath, E. Bergeron, M. Cracraft, and S. E. Deustua, Probing for Evidence of Plumes on Europa with HST/STIS. The Astrophysical Journal, 829 (2):121, 2016. http://stacks.iop.org/0004-637X/829/i=2/a=121

 

Space Saturday

Solar System Science Pouring In

After Perihelion (which would be a good name for a band), the Rosetta team continues to release new studies of 67P/CG. To date, most of the analysis is based on data from the first months in orbit, the perihelion will come out later (probably in time for big meetings in December and January).

One study examined fissuring on the surface of the comet, published in Geophysical Research Letters. Now that we have close up views, we can see many different fissures and cracks in the surface, which gives us basis for inferring some of the erosion that occurs on the comet. Of course, it will be really interesting to compare the “before” images to similar images collected after perihelion, which should show many changes which will tell us what happened.

The Rosetta team also has examined the magnetic fluctuations, dubbed “singing”, observed last year. These waves are different from what has been observed in other comets, and the team theorizes that they are due to the behavior of the plasma field at the time when 67P/CG was still cold and the plasma cloud small. The observations show the unexpected “singing” abated around February, as the comet came closer to the sun. In the near future we should have observations from perihelion, which may well show the development of the “song” like those observed in other comets.

it’s difficult to keep up with all the reports, and we haven’t even got to perihelion yet.  (“We haen’t even got to perihelion yet” would be a great title for a novel.)

Meanwhile, the Dawn spacecraft is comfortably orbiting Ceres at its final altitude of 1470 km. Each 11 days, Dawn completes a map of the surface of Ceres at three times the resolution of any previous imaging. This spacecraft is an awesome piece of engineering to last this long and collect so much data.

OK, Ceres looks kind of like the moon, all grey and cratered. But now we have really, really detailed maps and, with multiple overflights, 3D reconstructions.

Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA http://www.nasa.gov/jpl/pia19631/the-lonely-mountain

 

A BBC report reminded me that the Cassini spacecraft is Still Out at Saturn (yet another good name for a band). <<link>> Cassini  launched in 1997(!), and has been touring the neighborhood of Saturn, observing the planet, rings, and many moons, and dropping the Huygens lander onto the surface (or at least methane lakes) of Titan. Awesome!

The probe is now preparing for its last loop away from Saturn before a final funeral plunge into Saturn in 2017.


 

  1. El-Maarry, M. R., N. Thomas, A. Gracia-Berná, R. Marschall, A. T. Auger, O. Groussin, S. Mottola, M. Pajola, M. Massironi, S. Marchi, S. Höfner, F. Preusker, F. Scholten, L. Jorda, E. Kührt, H. U. Keller, H. Sierks, M. F. A’Hearn, C. Barbieri, M. A. Barucci, J. L. Bertaux, I. Bertini, G. Cremonese, V. Da Deppo, B. Davidsson, S. Debei, M. De Cecco, J. Deller, C. Güttler, S. Fornasier, M. Fulle, P. J. Gutierrez, M. Hofmann, S. F. Hviid, W. H. Ip, J. Knollenberg, D. Koschny, G. Kovacs, J. R. Kramm, M. Küppers, P. L. Lamy, L. M. Lara, M. Lazzarin, J. J. Lopez Moreno, F. Marzari, H. Michalik, G. Naletto, N. Oklay, A. Pommerol, H. Rickman, R. Rodrigo, C. Tubiana, and J. B. Vincent, Fractures on comet 67P/Churyumov-Gerasimenko observed by Rosetta/OSIRIS. Geophysical Research Letters, 42 (13):5170-5178, 2015. http://dx.doi.org/10.1002/2015GL064500
  2. Richter, I., C. Koenders, H. U. Auster, D. Frühauff, C. Götz, P. Heinisch, C. Perschke, U. Motschmann, B. Stoll, K. Altwegg, J. Burch, C. Carr, E. Cupido, A. Eriksson, P. Henri, R. Goldstein, J. P. Lebreton, P. Mokashi, Z. Nemeth, H. Nilsson, M. Rubin, K. Szegö, B. T. Tsurutani, C. Vallat, M. Volwerk, and K. H. Glassmeier, Observation of a new type of low-frequency waves at comet 67P/Churyumov-Gerasimenko. Ann. Geophys., 33 (8):1031-1036, 2015. http://www.ann-geophys.net/33/1031/2015/

 

Space Saturday

 

Spacecraft Getting Up Close And Personal With Small Bodies

As discussed earlier, the Rosetta spacecraft swooped low past comet 67P/CG on 14 February. Apparently, the images have been downloading ever since. It is easy to forget that Rosetta is a long way away, and has only so much bandwidth!

ESA released some imagery this week, including a close up that caught Reosetta’s shadow on the surface. This goes to show you just how close it passed.

Close-up view of a 228 x 228 m region on the Imhotep region on Comet 67P/Churyumov-Gerasimenko, as seen by the OSIRIS Narrow Angle Camera during Rosetta’s flyby at 12:39 UT on 14 February 2015. The image was taken six kilometres above the comet’s surface, and the image resolution is just 11 cm/pixel. Rosetta’s fuzzy shadow, measuring approximately 20 x 50 metres, is seen at the bottom of the image. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA From: http://www.esa.int/spaceinimages/Images/2015/02/14_February_close_flyby

 

Graphic to illustrate the difference between how a sharp shadow is generated by a point source (left) and a fuzzy shadow by a diffuse source (right). Credits: Spacecraft: ESA/ATG medialab. Comet background: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0 From: http://blogs.esa.int/rosetta/files/2015/03/RosettaPenumbra.jpg

Meanwhile, in another part of the solar system….

NASA’s Dawn spacecraft is closing on Ceres, as planned, and entered orbit Friday. The arrival is hardly climactic, as the spacecraft approaches via a sedate spiral.


There is considerable interest in some “bright spots”, that are now quite visible. These areas are really, really bright compared to the rest of the surface. What are they?

Ceres rotates in this sped-up movie comprised of images taken by NASA’s Dawn mission during its approach to the dwarf planet. The images were taken on Feb. 19, 2015, from a distance of nearly 29,000 miles (46,000 kilometers). Dawn observed Ceres for a full rotation of the dwarf planet, which lasts about nine hours. The images have a resolution of 2.5 miles (4 kilometers) per pixel. Dawn’s mission is managed by NASA’s Jet Propulsion Laboratory, Pasadena, California, for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. The University of California, Los Angeles, is responsible for overall Dawn mission science. Orbital ATK, Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team. For a complete list of acknowledgments, visit: http://dawn.jpl.nasa.gov/mission Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA From: http://dawn.jpl.nasa.gov/multimedia/Ceres_Awaits_Dawn.asp

 

One intriguing thing is that “the European Space Agency’s Herschel telescope reported last year seeing water vapour coming from two sectors on Ceres. One of these sectors includes the location of the spots.

Perhaps an impact or other event has cause ice to melt, in a “volcanic” cloud of vapor, leaving deposits or exposed undersurface.

Well, we shall see.

Space Saturday

ESA DG Rethinking Data Embargos

Apparently ESA is feeling pressure to make a better public spectacle from Rosetta and other space missions.  The conventional policy embargoes the data for six months or more, allowing the scientists who created the data to analyze and publish it before releasing to the general public.

Earlier I posted an explanation of the policy, and also what the scientists will be doing, and why the embargo makes sense.

Naturally, the public and funding agencies would like all the data released immediately.  Poof.  Just like in the movies.  And nowadays, Google et al. would like all the data immediately (for free), so they can exploit it (for profit).

The BBC reports that Jean-Jacques Dordain, ESA’s director general, would like to try to release more data sooner.

Based on experience with Rosetta, where the media and the Internet have had to be content with relatively low resolution images, even as the science teams have much, much better imagery in process.

I’m sure that there is room for some changes here.  Usually, there is a LOT of data, and not much reason for PIs to sit on data they aren’t using.  Also, there isn’t any reason why selected “early snapshots” can’t be released to the media, providing that the funders are willing to pay for that activity.  (Science teams are funded to do science, not special effects.)

I’m also sure this will need careful thought, because the proprietary access is one of the prime motivations for science teams to participate in decade long projects.  When you dedicate many years work without results, you hope to get first crack at the big discoveries.  Removing that opportunity may make it difficult to hold together teams for long projects.

Rosetta at AGU

The Rosetta project presented at the AGU meeting last week, giving a status report for the recent activities and Philae landing.

There was more confirmation of the rough landing of Philae, including a graphic image snapped at initial touchdown.

Philae’s blurred view during its first bounce on 12 November 2014. Credits: ESA/Rosetta/Philae/CIVA

The Philae team think there is a good possibility that the lander will be able to recharge and wake up as 67P nears the sun, perhaps in a few weeks.  Fingers crossed!


 

I note that there has been disappointment and complaints because almost no data has been released, no results reported, and no dramatic movies.

Grrr.

Look people, this is real science, not Hollywood.  Unlike TV, you don’t just push a button and receive the results.  Data analysis is hard, obsessive, work; and it takes time.  And the results are mostly not going to be splashy Hollywood story telling.

(I don’t think the plucky underdog outsiders using intuition will out do the stodgy official scientists who natter on about “logic” and “science”.)

Try to grow up and understand how the world really works.

First of all, data collection has only begun.  The main study is going to be a series of measures over months as the Comet approaches the sun.  We won’t even have all the data until next year.

Second, for the data already collected, there is a lot of work that will be done before there is anything to tell the public.

First, they have to check every bit of data, cleaning out junk and cross referencing to get a dataset that is as accurate as possible. (This requires art as well as science–real data is messy.)

Second, the data needs to be analyzed using theoretical models developed over the last decade.  This may involve comparing multiple hypotheses, trying to separate alternative explanations, and modifying the models in light of the data.

Third, these analyzes need to be compared to other results to cross check and draw the bigger picture.

Then, the results will be written up and submitted for review and correction.

Only then will there be public results.