Tag Archives: Ceres

Wither Dawn?

The Dawn spacecraft has chalked up some amazing discoveries in the time it’s been orbiting the dwarf planet 1 Ceres — the planet does not have the subsurface ocean that was anticipated, and its weird shiny spots are some type of salt (and planetary scientists are having spirited debates over what type of salt exactly).  But one thing we knew going on: thanks to the problem with Dawn’s reaction wheels, which forced it to expend more propellant to maintain orientation, Ceres would be Dawn’s final resting place.  Dawn would never be able to break orbit the way it left Vesta and go on to a third target.

Well, good news!  Turns out the mission controllers have been so fastidious with the propellant that there is way mor e left than they were expecting at this point.  They actually do have enough to leave Ceres orbit and go on to an incredible third target!  Which means that now they face a very difficult decision: to go or to stay?

If you were them, which would you pick?  Stay at Ceres, and continue investigating deeper and deeper into this strange world, or leave orbit and go on to a third target?

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Space Probe Catchup: Hayabusa 2, Curiosity, New Horizons, and Dawn – Occator Crater revealed!

I’ve been busy lately, so I have not had much time to write, so here’s the latest on three different deep space probes!

First off, Hayabusa 2 made a successful flyby of the Earth on December 3, flying about 3,090 km above Hawaii at closest approach.  The spacecraft was performing a gravity assist maneuver, and controllers now report the maneuver was performed flawlessly: Hayabusa 2 is right on target to encounter asteroid 162173 Ryugu in 2018.  Hayabusa 2 is a follow-on to the original Hayabusa mission, which encountered serious difficulties but still managed to return samples from asteroid 25143 Itokawa.  Hayabusa 2 builds on the lessons learned from that mission and should be able to return much larger samples, scheduled for 2018.  It will also deploy a set of landers, both Japanese and European.

Earth from Hayabusa 2, just after the gravity assist.  Summer has reached the South Pole.

Earth from Hayabusa 2, just after the gravity assist. Summer has reached the South Pole.

Here’s a fantastic animation showing its flight:

Next, Curiosity!

The Mars Science Lander “Curiosity” is now well into its mission exploring Mount Sharp in the center of Gale Crater.  Its latest object of interest is a field of sand dunes.  The going will be difficult, and the team will be very cautious, since it was sand dunes that irretrievably mired MER-A “Spirit”.  This is the rippled surface of “High Dune”, within a dune field named Bagnold Dunes.

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The texture and particles are very intriguing, and Curiosity may learn a lot when it samples them.  They’ve already used the wheels to help get a peek below the surface:

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And still New Horizons returns data!

The probe is continuing its long, slow plod through the enormous data set that it collected at Pluto.  Color data is now available for those high resolution images taken at closest approach, and it only looks wilder:

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Click for the larger image.  It’s really quite weird looking.  The geology must involve some processes that simply don’t happen on Earth, although some of it looks distinctly familiar to our eyes.

Last but not least, Dawn!

Dawn has continued studying 1 Ceres, the closest of the dwarf planets, and there is new information on the mysterious lights in Occator Crater!   Occator Crater has by far the brightest spots on Ceres, but the small world is sprinkled with bright spots.  New spectrographic analysis is consistent with all of those spots being a salt called hexahydrite, which is a type of magnesium sulfate.  Furthermore, all of the spots are associated with impact craters.  This allows them to rule out ice volcanism.  They  believe the spots are salt left behind after water sublimated away following impacts which exposed a briny water layer just below Ceres’ crust.  They aren’t yet suggesting that layer to be liquid, by the way.  It could well be ice, which would rapidly boil away in the sunlight this close to the Sun.  (Ceres is near the limit of our Sun’s golidlocks zone.)  Occator Crater they think is brightest because of relative youth, and possibly also a more energetic impact digging deeper into this layer.  It appears that the water may not have finished sublimating away from Occator Crater, as there is evidence of water vapor accumulating in the crater from both Dawn and also the Herschel Space Observatory.

Another team was analyzing for evidence of ammonia compounds on Ceres, and came up with a lot of evidence, locked up in clays.  This is particularly interesting because surface ammonia is even more volatile than water; that Ceres has some suggests it formed further away from the Sun than its present position.  Perhaps interactions with the giant planets pushed it in.  Ceres is also unusually rich in water ice for a main belt asteroid, which would tend to suggest the same thing.

Here is a color-enhanced image of Ceres rotating.  The enhanced colors help to pick out subtle differences but should not be interpreted as what the human eye would see.

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China launches Tianhui 1C, and other spacecraft news

Tianhui 1C, a mapping satellite built for the same basic mission as the Landsat series, launched from Jiuquan Space Center on Monday, aboard a Long March 2D rocket:

In other spacecraft news, Dawn is moving into its final orbit around Ceres, a low one which hopefully will finally answer the many questions that have been raised about Occator Crater and other strange features of this surprisingly peculiar world.

And Cassini is preparing to dive closer than ever to Enceladus.  Tomorrow, the spacecraft will plunge deep into the water vapor plumes above Enceladus, directly sampling them.  This will not be its closest pass to Enceladus (that was the last pass) but it will be the closest that passes through the plumes.  Should be exciting!

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New looks at Occator Crater from the Dawn spacecraft!

Dawn has gotten through its thruster issues and is plugging away at the science.  Mission controllers are currently planning to conduct six full mapping cycles over the dwarf planet so that they can produce accurate 3D maps of Ceres, and they’re off to a fantastic start.  But of course what most folks are waiting to know is this:

What the heck are those spots???

And honestly, they still don’t know.  But they do have the best images yet of them, and they’re starting to look somewhat resolved.  And the 3D imagery shows that the really bright spot in the center of the crater is not the peak of a mountain; it’s actually in more of a dip.  It’s quite a puzzle, but we’re getting closer to the point where that question might finally get answered.  Here’s the latest overhead look, and it’s breathtaking (click for full res):

PIA19889

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The veils of Ceres, obscuring the bright lights

With Dawn fully recovered, science data is coming back again and possibly yielding some new clues to the puzzle of the bright lights in what has been named Occator Crater.  At certain times of day, the crater with at least nine reflective spots in it appears to have some sort of haze in it. It might just be overexposure, or it could be the elusive source of the water vapor signal that the Hershel Space Observatory had detected, or it could be something more particulate in nature.  The nature and composition of this haze will almost certainly shed some light (hah) on the nature of the spots as well, but for now it remains excitingly mysterious.

Planetary Society: Dawn at Ceres: A haz in Occator cater?

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Dawn is back up and running!

The Dawn spacecraft suspended science activities on June 30.  The computer had noticed that the spacecraft’s orientation didn’t match with what had been commanded, so it reset itself into safe mode and awaited commands.  The problem turned out to be much more significant than what struck New Horizons: there’s a mechanical problem with the gimbal on engine #1.  That’s the bad news.  The good news is that Dawn has three ion engines.  So after conducting some tests on the gimbaling mechanism for engine #2, engineers have switched Dawn over to that engine, and it is now working its way into the third orbit, the High Altitude Mapping Orbit, which despite the name is actually lower than the current orbit.  It will take five weeks for the ion drive to bring the spacecraft down to an average altitude of 1,500 km (900 miles) above Ceres, so around about Labor Day we can start watching for new imagery at better resolution than any yet!

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Dawn’s bright spots: still weird

Now in its second survey orbit, Dawn has taken pictures of the bright spots with a faster shutter speed.  It’s really too short an exposure for dim Ceres, but the hope was to get a better look at the bright spot.  Unfortunately, it’s STILL too bright to make out details!  So the mystery remains.

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