Tag Archives: Ceres Asteroid Mission

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

 

Screaming Pluto Flyby

… isn’t a bad name for a band…

NASA’s New Horizons is screaming in (well, it would be screaming if there was some air) on Pluto this week. No brakes!  Can’t stop!

This is a historic first, the closest any probe has come to Pluto, and checks the last box on the “visit the planets” dance card. (From Sputnik to now, it took just under 58 years.)

If nothing goes wrong, we’ll get some pretty good images, snapping away like mad.

New Horizons Dashboard

In contrast to the quick and “whatever we can grab” Pluto flyby, Dawn is doing a slow and very thorough survey of Ceres. Currently in a 4400 km orbit, Dawn is finding a lot of interesting geography, which will have to be puzzled through in the ensuing years.

Marc Raymon gives us a nice run down on some of the high lights of the observations, and the implications. He also tells us a little about communication with Earth from that distance. (Hint to NASA PR people: this post is way more interesting than the continuing hoo-haw over “guess what the bright spots are”.)

Now Dawn will spiral yet lower, to gather much more high resolution data. This ion drive thing is awesome!

And out at 67P/CG, Philae seems to be alive, but communication to the orbiter is spotty.  It’s great to hear that the lander has survived (seriously good engineering job), though it isn’t clear we’ll be able to get much information back.

 

Space Saturday

Ceres Close Ups, and Waiting for Philae

In the solar system this week, the New Horizon probe is swooping in on Pluto, for a screaming flyby, with closest approach on 14 July. In the past month, the probe has seen several moons, albeit briefly.

Data from the New Horizon probe has been augmented by observations from the Hubble Space Telescope, which is obviously closer to Earth, but also way larger and more capable. This study has indicted that the smaller moons of Pluto / Charon have quite chaotic orbits around the twin planets. I guess that’s not too surprising, though I wonder if these moons are recent acquisitions. I mean, Pluto has been there a long time, so things should have settled down by now, no?  I expect we’ll learn more from the flyby.

Meanwhile, Rosetta is still looking for the little lost Philae lander. The Rosetta orbiter took imagery in December that should cover Philae’s location, but the lander has not been picked out. As the comet heats up, the gasses boiling off the comet have been too much for Rosetta’s navigation system, so the probe has not been able to swoop lower for closer looks.  (This is an interesting, if inconvenient finding that we’d never know without actually visiting a comet close up.)

In the coming weeks, the sunlight on 67P/CG will be increasing even more, and it is possible that Philae will be able to charge its batteries. If that happens, and the systems have survived months of extreme cold, then Philae will wake up and try to contact the Rosetta orbiter. Even if we don’t get any science, I think we all want the lander to wake up, and show us just how well it was built!

Out at Ceres, “deep into the main asteroid belt between Mars and Jupiter”, the Dawn spacecraft has been orbiting and amassing images and measurements for the past month. Last week, Dawn completed a maneuver into a lower “survey orbit”, about 4400 KM altitude. It is recording and transmitting images from this second orbit, and later it will move lower still.

Dawn’s spiral descent from its first mapping orbit (RC3) to its second (survey). The two mapping orbits are shown in green. The color of Dawn’s trajectory progresses through the spectrum from blue, when it began ion-thrusting on May 9, to red, when ion-thrusting concludes on June 3. The red dashed sections show where Dawn is coasting, mostly for telecommunications. The first two coast periods include OpNav 8 and 9. Image credit: NASA/JPL-Caltech

I would note that the Dawn team is rightly proud of their ion propulsion system, which has made possible this incredible feat.

 

Space Saturday

Space Probes Waiting for Summer

Space exploration certainly has a lot of “hurry up and wait” to it, no? Decades of slow travel, followed by frantic activity, followed by weeks and months of data crunching. It’s not the way Hollywood shows it!

This summer we are following three robot probes, “New Horizons” (closing in on Pluto for a dramatic flyby), “Rosetta” (riding comet 67P/CG around the sun), and “Dawn” (orbiting Ceres).

Lot’s will happen this summer.

New Horizon

We are waiting patiently for a 14 July Plutopalooza.  The imagery and data isn’t exciting yet, though we are getting the closest views ever, and finding moons.  I’m sure we’ll know a lot more real soon now.

Rosetta

Rosetta is clucking away, sucking in unprecedented close up data as 67P/CG heats up and spews gas. It is now just visible from Earth, showing the beginnings of the class comet tail we all love to see.

Comet 67P (center) with a visible tail taken at the TRAPPIST observatory in Chile on April 18, 2015. Image Credit: E. Jehin and Team.

(Amateurs are invited to participate and contribute in the ground observations.)

As a reminder of why the Rosetta expedition is significant can be seen by comparing the image above (a pretty good view from Earth) with the imagery from Rosetta, such as:

There really is no comparison.

And Rosetta is gathering lots of other data from many instruments.

Dawn

As Dawn gets down to business, the current interest is the now famous bright spots. This week we have an even clearer image from NASA:

This image of Ceres is part of a sequence taken by NASA’s Dawn spacecraft on May 16, 2015, from a distance of 4,500 miles (7,200 kilometers). Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn will collect more data and then move to a lower orbit and collect even better imagery.

 

 

Space Saturday

 

 

What Are The Sparkly Spots On Ceres?

The “Dawn” spacecraft has finished downloading the navigation images, and has now begun systematic imaging of Ceres from a circular 13,500 KM polar orbit.

This animated sequence of images from NASA’s Dawn spacecraft shows northern terrain on the sunlit side of dwarf planet Ceres. Dawn took these images on April 14 and 15 from a vantage point 14,000 miles (22,000 kilometers) above Ceres’ northern hemisphere. The spacecraft was settling into its first circular orbit, called RC3 (for “rotation characterization 3”), which it will begin on April 23. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

These images were captured a week ago—it takes a while to transmit them back, and to process the data. A reminder of the magnitude of the enterprise: this is pretty far away from home. The fact that the software is still working after years untended is amazing.

So far, Ceres is not an especially photogenic destination. The main point of interest so far are the mysterious “bright spots”, visible in this week’s images. It isn’t known what they are, so we’ll all be looking to the upcoming observations for more clues.


Speaking of huge undertakings, we commenmorating the 25th anniversary of the Hubble Space Telescope.  Though now superceded by technical advances, this has been one of the most significant scientific instruments ever.

And, by the way, there are gazoogabytes of data from Hubble available for anyone who wants it. E.g., start with the Hubble Legacy Archive.  (Astronomers are some of the original and most consistent practitioners of true Open Data policies.

 

Space Saturday

Real Life For Solar System Probes

As we follow our space probes this spring, we are reminded how much we are all spoiled by Hollywood spaceships that not only make cool “whoosh” sounds, but magically pop between interesting places in minutes without spending any boring time getting there.

Unfortunately, real space travel is much slower and trickier, and robot spacecraft aren’t as magical as seen on TV. In the past few months, we have seen NASA’s Dawn probe arrive at Ceres and ESA’s Rosetta at comet 67P/CG, both of which took a decade to get there. And even now that they have “arrived”, things are still “exotic” by Earthbound standards.

Dawn’s slow looping progress…

Dawn arrived at Ceres last month, achieving gravitational capture on 6 March. But this is a long, slow mission, and the spacecraft has been slowly looping around in a long spiral in, to a target 15KM circular orbit in a few weeks. Furthermore, it has been on the dark side of Ceres which, out there, is really, really dark! So no imagery until the mapping orbit is achieved.

Dawn’s final swoop down to RC3 orbit. The sun is off the figure far to the left, and Ceres’ north pole points up. The farther Dawn is to the right side of Ceres here, the smaller a crescent it sees, because the illumination is from the left. The white circles are at one-day intervals. The trajectory is solid where Dawn is thrusting with its ion engine, which is most of the time. The labels show four optical navigation sessions, where it pauses to turn, point at Ceres, conduct the indicated observation, turn to point its main antenna to Earth, transmit its findings, turn back to the orientation needed for thrusting, and then restart the ion engine. Dawn was captured into orbit on March 6. Note the periods on the right side of the figure between OpNav 5 (on March 1) and OpNav 6 (on April 10) when Dawn pauses thrusting for telecommunications and radio navigation but does not take pictures because it would have to point its instruments too close to the sun. Apodemeter is the Dawn team’s word for the highest altitude in orbit, in analogy with the more common term apogee, which applies for Earth orbits. (Demeter is the Greek counterpart of the Roman goddess Ceres.) Dawn was at its apodemeter of 46,800 miles (75,400 kilometers) on March 18. For more on Dawn’s approach trajectory, see the overall description and figures from other perspectives in November (including the motion into and out of this flat depiction), further details (including the OpNavs) in February and an animation in March. Credit: NASA/JPL

 

Marc Rayman gives us a ton of cool information about real life out there in Ceres orbit: reconfiguring the spacecraft from travel to observation mode, dealing with the loss of 2 of 4 maneuvering flywheels, calibrating the camera and so on.

Now that Dawn is there, it will begin a long campaign of observations, spiraling in to successively closer orbits as the months go by. And this will be the end of the mission: she will fade out and someday fall onto Ceres.

Rosetta’s navigation woes…

The Rosetta spacecraft has been swooping in for close passes to comet 67P/CG, which is heating up and developing an atmosphere as the ice steams off. This means that these passes are actually quite dangerous for the deep space adapted Rosetta: she’s not intended to operate in an atmosphere.

Example of Rosetta’s recent flyby trajectories at Comet 67P/C-G. Credit: ESA.

The mission has reported on problems they have had, which are kind of interesting. The big problem has been that the automated star finder system has been confused by all the ‘bright spots’ from the escaping gasses. The star finders continuous watch the sky for familiar groups of stars, which are used to keep the spacecraft on course and oriented correctly. The latter involves, critically, pointing the antenna at Earth.

Apparently the last pass encounters so many false “sightings” that the star finders got lost and the antenna skewed away from target Earth. The signal was lost for a while and data could not be transmitted.

The spacecraft recovered, though not before entering a “safe mode” partial shutdown.

(“Safe mode” sounds warm and cuddly to me, but I know that space scientists hate safe modes—they are what happens when all else has failed.)

I don’t know about you, but I’ve always be awed by guide star astrogation—it is so elegant and so universal. The spacecraft knows exactly where everything is….

And for that matter, orienting spacecraft with flywheels just blows my mind–again, so elegant, so flat out Newtonian.

 

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