Dawn of a new Vesta

By Phil Plait | July 18, 2011 2:00 pm

The Dawn spacecraft is now in orbit around the main belt asteroid Vesta! Yay!

The spacecraft entered orbit around the main belt asteroid on Saturday, July 15. Two days later — today — it snapped this spectacular high-res image:

[Click to enprotoplanetate.]

Wow, what a mess! As expected, it’s littered with craters, but there are some interesting things to note. Some craters appear to be very deep, while others are shallow — that indicates a different type of terrain (asteroidain?) where the impactors hit (although in some cases it might be a lighting effect; a more direct sunlight angle makes craters look shallow). The grooves I mentioned in a previous post are everywhere, some looking more like scarps (cliffs) now. And look at that huge cliff on the upper right! I’ll be very curious to see that area at different angles. Is it part of a big basin, a collapse feature? Or is it a cliff caused by cracking in the surface? By the way, that lump in the center casting a shadow to the left is actually a mountain or mound of some kind well over 100 kilometers across.

The resolution is stunning; each pixel in the high-res version is about 1.4 km (0.9 miles) across — the asteroid itself is 530 km (330 miles) wide. Dawn is orbiting at a distance of 16,000 km (9900 miles; a bit more than the diameter of the Earth) and will slowly lower its orbit over time. Vesta’s mass is uncertain, so engineers played it safe and put it into a high orbit. This will allow an accurate mass to be determined, and then scientists and engineers can calculate how much thrust is needed to safely close in. That will take some time, about three weeks. During that time Dawn scientists will search the region around Vesta for tiny moons. None has ever been seen from Earth, but there’s nothing like being there.

… and I’ll add, we almost didn’t go. Back in 2005/6, this mission was actually canceled by NASA, causing quite the stir in the astronomy community. However, a strong voice was raised against this cutback, and Dawn was back on. After a long, long journey, it’s now where it belongs: in deep space, exploring, doing science, and expanding our frontiers.

I can hope the same will be true for JWST.

Related posts:

Dawn approaches
On approach to Vesta
A new day for Dawn
Hubble spins an asteroid

CATEGORIZED UNDER: Astronomy, NASA, Pretty pictures, Top Post
MORE ABOUT: craters, Dawn, scarps, Vesta

Comments (46)

  1. Greg

    To the upper-left (top-center) of that large cliff there is a very surprised onlooker.

  2. Oli

    Is that mountain the central peak of the huge crater? How tall is it?

  3. Lonny Eachus

    I would expect grooves, since with its low gravity many impactors undoubtedly graze.

  4. MrCompletely

    In other words, asteroids seen up close look exactly like you’d expect from watching Empire Strikes Back. But with at least marginally fewer giant worm thingies.

  5. I find the lack of rays from ejecta near the craters interesting. Phil, why would this be so?

  6. Georg

    I think its due to the low gravity,. Almost nothing will fall back
    after an impact.

  7. Al

    Interesting question, Angel Bomb. I wonder about that myself. Perhaps it has something to do with the low mass; I’d suspect that a certain amount of gravity is needed for a plume of ejected material to fall back down and remain behind as a visible ray.

  8. lqd

    I think the mountain in the middle is probably the central peak of a very large crater, and the large cliff to the upper left is part of the crater wall. Could that be the large crater detected by Hubble that blasted off most of Vesta’s polar region?

  9. Magrathea

    @angel bomb

    Most probably because the gravity is so low on Vesta’s surface, on the moon gravity pulls material back down, on Vesta it might just blow off into space.

  10. Sir Chaos

    This is beautiful.

    BTW, have any of you read “Marooned off Vesta” by Isaac Asimov? It´s the first SF story I ever read (I must have been about 8 or so), and coincidentally also the first Asimov ever sold, so of all the asteroids Vesta will always be “special” for me.

  11. Anchor

    “Is it part of a big basin, a collapse feature?”

    Still consistent with a big impact followed by local collapse or slumping. There is a very unambiguous indication of slides on BOTH sides of a section of that cliff-edge which could only be if that was an up-lifted ridge-line. And though the feature is not always a “cliff”, it is part of a discontinuity that can be traced concentrically (if unevenly scalloped) around that big mound. That is entirely consistent with a giant impact feature, complete with huge central ‘peak’ and rim.

    I’m gonna go out on a limb here and just mention that the ‘central peak’ strongly reminds me of a resurgent lava dome often found grown within newly-erupted volcanic calderas. It seems too big to be the result of dynamic impact rebound alone. It might have grown bigger by oozing out partial melt from the interior…

  12. Keith Thompson

    In some areas, it looks like a lot of the grooves are at right angles to each other. That’s probably just coincidental — but *somebody* is going to point at some feature and call it a cross.

  13. OtherRob

    Some craters appear to be very deep, while others are shallow — that indicates a different type of terrain (asteroidain?) where the impactors hit (although in some cases it might be a lighting effect; a more direct sunlight angle makes craters look shallow).

    Would not impactors of of different sizes and/or relative velocities also account for the differences in crater sizes?

  14. Gilon

    I support your hypotesis, and I would also like to imagine that there were some time in proto-solar system 1 or maybe 2 small-Planet sized objects in the Orbit of the Asteroid Belt and this big crater over Vesta might be the only evidence of that Chaotic Orbit in the early times of the Solar system.

    I feel like writting a Science fiction book now

    :) This picture is so Exciting.

  15. Alan(UK)

    I don’t know where this fits but another spacecraft has reached orbit:

    Russian Scientific Spacecraft Spectrum-R Successfully Launched from Baikonur


    Russian Observatory Intended to Study the Universe Reaches the Targeted Orbit


    It has been a long wait but they have finally got it there. Very Long Baseline Interferometry with a baseline that is out of this world! Yay!

  16. Peter C

    The tracks obviously are because this is where the Interplanetary BMX meet is held

  17. Congratulations to the people of the Dawn mission. Great image and looking forward to many more including & especially those of Ceres later too. :-)

    Vesta is, btw. apparently the source of many meteorites and a cluster of asteroids with similar composition as determined by spectral analysis. There’s ahuge southpolar crater on Vesta – looking forward to seeing Dawn‘s close up images of that. An impressive little world of it’s own with lava and possible geological differentiation. Any signs of any possible Vestan moonlets? Guess they’d say they’ve found any. But are they ruled out now?

    Click on my name for Vesta’s wikipedia page for more info. :-)

    However, a strong voice was raised against this cutback, and Dawn was back on. After a long, long journey, it’s now where it belongs: in deep space, exploring, doing science, and expanding our frontiers.
    I can hope the same will be true for JWST.

    Seconded by me.

    If I recall right much the same thing also happened to the NewHorizons spaceprobe currently travelling to Pluto so there’s certainly precedent here. Hoping for the best for the James Webb Space Telescope – hard to believe they won’t continue with it now.

  18. @10. Sir Chaos :

    This is beautiful.BTW, have any of you read “Marooned off Vesta” by Isaac Asimov? It´s the first SF story I ever read (I must have been about 8 or so), and coincidentally also the first Asimov ever sold, so of all the asteroids Vesta will always be “special” for me.

    As a huge Asimov fan myself, I sure have! :-)

    Oh & guess what image now accompanies its entry on Wikipedia? 😉

    (Click on my name and see.)

  19. Kappy

    @Messier Tidy Upper:

    “There’s ahuge southpolar crater on Vesta – looking forward to seeing Dawn‘s close up images of that.”

    I’m pretty sure that is what we are looking at in this image (although I’m not sure you could call it a closeup), the crater is thought to be some 300km wide. I think the “Mountain” in the center of this image is actually from the rebound of the impact. The scarps on the upper right and down along the right edge are likely the rim of the impact crater. From a “side” view, Vesta should look kinda flattened due to the fact that a huge amount of the southern hemisphere has been blown off by the impact.


  20. Das Boese

    First MESSENGER and now Dawn, this is shaping up to be a great year for space exploration. And it’s barely half over!

  21. ethanol

    Emily at the planetary society blog has posted a cool new picture from a different angle where you can really see the striations around that peak. http://www.planetary.org/blog/article/00003104/

  22. Buzz Parsec

    Peter C, were you at TAM9? There was a big BMX convention at the same hotel. (I’m at a Starbucks, recaffeinating and catching up on the intertubes while wending my way to the airport. P.S. BA, great meeting you and Mrs BA!

  23. So beautiful but it looks so dead……..

  24. @ ^ Cynthia : Well Vesta’s no B-612* but it is a lot roomier and, who knows, it may one day have life brought out to it. If we humans ever venture out that far in person.

    @22. Kappy : Thanks. :-)

    I never would have guessed I was looking at the south polar crater here!

    @16. Alan(UK) : Also in other space-related news, just heard on the TV (a headline at that) that the Shuttle astronauts have just said farewell to the ISS crew and are heading home now or very shortly. Must admit I thought they still had more time left.


    * The Little Prince’s asteroid home – house-sized with 3 volcanoes. Vesta was once volcanic too .. doubt we’ll find any roses there though! 😉

    Click on my name for its wiki-page.

  25. MadScientist

    I vote for the lighting effect; isn’t it peculiar how all the ‘shallow’ craters are in the same region and the craters get deeper as you get further away and have the light coming in more from the edge?

  26. JB of Brisbane

    @Messier #27 – I was wondering if I should make another “Little Prince” reference here. Thanks for going first.

  27. Blake

    I guess I’ve just been spoiled by all the amazing missions that happened in the first half of the last decade, but, well, I’m just not getting excited about this mission yet, like…. at all. I feel bad for saying it, I mean I know it’s a first, but after NEAR Shoemaker, Cassini and the Huygens lander, Hayabusa, the Mars rovers, the DS1 Borrelly flyby, Deep Impact, etc. this is kind of, eh….boring. It’s just a dusty old rock that looks pretty much how everyone imagined it would. Hopefully Ceres will be more exciting since it’s differentiated and has water ice on the surface, maybe even a subsurface ocean. Don’t get me wrong, the scientists on Dawn obviously have a lot to be proud of and I’m really glad to see the DS1 ion engine technology being put to practical use on a full deep space science mission, but more than anything, at least thus far, this mission makes me appreciate what a really amazing time for exploration the early ’00s were.

  28. Messier Tidy Upper

    Update : Atlantis has, indeed, undocked from the International Space Station for the final time. This was covered live by a local Aussie TV news show.

    See :


    for news or NASA’s Shuttle page here :


    for the latest. Mission elapsed time now 10 days, 17 hours 43 minutes.

    I thought this mission (STS-135) was to last twelve days and, indeed, was extended by one day. Wikipedia :


    seems to confirm this providing a landing scheduled for the 21st July 2011 5:56 a.m. EDT (9:56 UTC) at KSC so I’m kinda surprised they’ve undocked and departed the ISS this far out from that date. Anyone here know why and care to enlighten us please?

  29. Georg

    Is there some chaperon along with dawn?
    You know, that a vestal virgin was buried alive when caught
    at an entanglement with some man….:=)

  30. PSP

    Hmmm, did anybody else notice that big footprint about 6 o’clock? Obviously, we’re not the first ones here… :-)

  31. QuietDesperation

    @ Blake: I know what you mean. Asteroids seem boring now. It’s no Titan landing. We’re so spoiled. :)

    MTU: Vesta was once volcanic too ..

    Are asteroids big enough to have geologically active cores? I haz a skepticism. It’s not orbiting a large planet that can flex it to create heat, like Io. Google suggests it’s still just a hypothesis.

  32. Calli Arcale

    Messier Tidy Upper — The Little Prince is one of my favorite stories ever. It still makes me cry. And there is actually an asteroid named for it now — 46610 Besixdouze. The name is French for “B Six Twelve”. (And 46610 is what you get if you convert the hexadecimal number B612 into decimal.) There is also 2578 Saint-Exupéry, and the asteroid 45 Eugenia has a moon which is named Petit-Prince.

  33. Calli Arcale

    QuietDesperation — there is another possibility I’ve heard suggested by people who know more about this stuff than I do. Volcanism points to a geologically active core, which requires something to melt it. That can be tidal flexing (Io, Europa), radioactive elements, or the lingering results of a really cataclysmic impact. This last is plausible for asteroids, which we know get smacked around a lot. But, as you say, it’s just a hypothesis — that it *could* happen doesn’t mean it does, and nobody’s actually seen any evidence that it’s happening. (But then, that’s what they said about Venus and Io. I won’t rule it out; we’ve been surprised before. But I won’t expect it either.)

  34. mike burkhart

    I’ve heard that some asteroids have moons , but this is the frist time I’ve heard that Vesta might have any . One idea I,ve read about is that we might be able to mine Asteroids for minerals in fact we may have to since minerals from the Earth may be depleated one day. Not to brag but on the video game Asteriods I’ve fliped the score (when it reaches 99999 the score returns to 0) on the original and the Atari 2600 , but as for Asteroids Deluxe I haven’t because the game is 100x harder then the original and can accomidate a higer score. in the updated version for Playstation the game ends after the last level .

  35. Boomer

    I love words that I can type into Google search with one hand, ie. Vesta

  36. Zucchi

    I see I’ve been beaten to the punch in referencing “Marooned Off Vesta”. Man, I wish Asimov were alive to see this. Think of the science column he’d write for F&SF. But, hey, we’ve got Phil!

    And, Boomer, I’m not going to ask why you need to be able to do the search with one hand. I’m excited too.

  37. andy

    I can’t wait until the topographic maps come out. Then we can start playing around with this in 3D programs to explore the place, it’s certainly got some landscapes worth seeing!

  38. I think Hoagland has completely lost connection to all reality. He was on Coast2Coast this morning spewing a bunch of garbage about geometric patterns on the surface of Vesta that could only be from an ancient, extinct society. And, of course, NASA is only releasing one image a day because they’re covering something up because they have lied about so much in the past blah blah blah….

    Does anyone actually listen to him seriously any more? Did they ever?

  39. Strahlungsamt


    Our old friend Richard C. Hoagland is on Vesta’s case already….. 90 degree angles that nobody else sees… Definitely proof of an alien civilization.

  40. Strahlungsamt

    I think someone beat me to the Hoagland article.

  41. MaDeR

    “I think Hoagland has completely lost connection to all reality.”
    You realised it just now?


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