On approach to Vesta

By Phil Plait | June 13, 2011 9:29 am

NASA’s space probe Dawn is on its way to Vesta, scheduled to settle into orbit around the solar system’s second largest asteroid on July 16th, about a month from now. On June 1st, when Dawn was still 480,000 km (300,000 miles) away from Vesta, it captured a series of navigational images that have been put together into a short animation:

That is so cool. You can see features, still too small to see clearly, but they’re there. And you can see them move as Vesta rotates — the 20 frames of the animation are repeated five times, covering 30 minutes or about 1/12th of Vesta’s 5.34 hour rotation period. That dark spot near the center is possibly a crater 100 km (60 miles) across; we’ll know a lot more about it in the next few weeks.

Vesta is about 550 km (330 miles) across and clearly non-spherical. It’s potato-shaped, and has a huge crater at its south pole. You can see in the video and the pictures here how the crater distorts the shape of the asteroid; the lower right section is flattened, where we see the edge of the crater. I suspect when we get clearer shots of that basin in July it’ll be spectacular.

I also suspect, from long experience in watching probes approach celestial bodies, that the crater won’t be the most amazing thing we see on Vesta. I don’t know what that thing will be, but over and again we’ve found that every time we visit another member of our solar system, we get profoundly shocked by what we see. This is the first large main-belt asteroid we’ll have ever visited for any length of time (others have been observed as probes flew past on their way to bigger and better things, but Dawn is the first that will orbit a main-belt asteroid), and whenever the adjective "first time" is used, it means surprises await… and that’s where the most fun is.

Video and image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA


Related posts:

- Vesta interest
- Hubble spins an asteroid
- Asteroid comparison chart, Part II

CATEGORIZED UNDER: Astronomy, NASA, Pretty pictures
MORE ABOUT: asteroid, Dawn, Vesta

Comments (45)

  1. Carey

    This video of a vista of Vesta has vested me with something that begins with V.

  2. Adam

    Oh man, I remember the Voyager approach videos and how shocking what we found in those places was. This excites me terribly. Brand new worlds always alter our very conception of what a “world” is and how it can form, or what it can be like. Very exciting time indeed.

  3. ELMO

    damn.! if that thing hit on earth it’s our end :)

  4. Gary Ansorge

    I love asteroids. Both Vesta and Ceres figure prominently in a short SciFi story I wrote some time ago(and no. It wasn’t published. Not good enough). I had a heck of a time figuring transit times between the two asteroids(at 1/10 G acceleration). I had thought Vesta was not quite round and as we see here, that was accurate. From spectral analyses and such, Vesta is thought to consist of a metallic iron–nickel core, overlying a rocky olivine mantle, ideal as a pit stop and manufacturing zone for asteroid colonies.

    REALLY looking forward to this probes visit.

    Gary 7

  5. Go back, GO BACK! There’s TWO of them!

    Let us hope that NASA’s investment was wholly spreadsheeted in either metric or Imperial units.

  6. How close will it orbit? My guess is that it will be pretty close to the surface due to the small size (mass, really) of Vesta.

  7. jamie

    Didn’t know that it was so non-sperical. Previously thought that Vesta and Ceres should qualify as planets, but maybe not. Anyway, I personally doubt that there’ll anything terribly new or interesting to see there. All the other asteroids that we’ve examined have proven to be rather blah. Just big rocks.

  8. jamie:

    I personally doubt that there’ll anything terribly new or interesting to see there.

    Didn’t they say the same thing about Jupiter’s moons, before Voyager arrived? A lot of people didn’t want to “waste” time and resources to even bother looking at them.

  9. WJM

    I love how planetary astronomy classifies all bodies as one of “spherical”, “oblate”, and “potato”.

  10. chris j.

    that dark spot isn’t a crater, it’s the formics’ base. oh wait, that was eros.

  11. Brian

    All these SF references in the comments, and nobody mentions “Marooned Off Vesta”?

  12. Bjoern

    @Brian: I briefly considered mentioning it, but then decided it was not worth the effort… So thanks to you. ;-)

  13. jamie

    Ken: I certainly don’t think that our robotic probes are a ‘waste’! But Jupiter’s moons were a wholly different matter, being a sort of miniature alien solar system. In contrast, we’ve already seen what asteroids look like, and as I said, they’re just ‘big rocks’. But I still look forward to seeing the images July 16!

  14. Doug

    Does anybody else see a face, turning to stare at the probe? Kinda freaky.

  15. Just Mike

    @ #16 Doug – It looks almost like the face on Mars. Do you suppose he has a twin?

  16. andy

    Well Vesta shows evidence of differentiation and Ceres seems to have substantial quantities of ice in its makeup, so they are probably substantially different from the smaller asteroids that have previously been visited. I’m particularly interested in Vesta as the huge impact basin at the south pole may provide (in relative terms) the deepest look into a differentiated object that we’re likely to get.

  17. Grimbold

    This is going to be so cool. Can’t wait for the 16th of July.

  18. dave chamberlin

    If someone from the future reads this please go back in time and put a SEE ROCK CITY billboard on Vesta. I’m not asking for world peace or the winning lottery number, just put one of those old billboards on this ancient potato.

  19. That is wicked cool. Too bad its blurry. :(

  20. That is wicked cool. Too bad its blurry. :(

  21. Jess Tauber

    Big crater? Thats a frakkin’ focusing manifold! The thing’s a planet killer, and you want to get its attention?

  22. Aaron

    Looks like the head of a “grey” to me . . . Richard Hoagland should have a field day with this one!

  23. Sam H

    @25 Aaron: I saw a face almost immediately myself!! I don’t think Hoagland will have a field day with such blurry images from this far-out, but whatever blurry things we see up close will drive him nuts!! :)

    And Jamie: true that the asteroid shouldn’t look too remarkable, but true science goes beyond the obvious appearances and digs as deep as it can go – point is, we’ll definitely find SOMETHING new with this one (I for one am just stoked to see how detailed a giant asteroid will look close up!! :) )

    And besides, for the moment, you CANNOT prove that a Monolith or something of the like is NOT there…;)

  24. David Zimmerman

    @21(dave), or “Free Ice Water at Wall Drug”

  25. Messier Tidy Upper

    NASA’s space probe Dawn is on its way to Vesta, scheduled to settle into orbit around the solar system’s second largest asteroid on July 16th

    Isn’t Pallas the second largest asteroid and Vesta the *third* largest one behind that and Ceres, BA? ;-)

    EDIT : Or are you excluding Ceres from the asteroid list because its a planet rather than giving it dual asteroid /planetary status?

    Great images already – can’t wait until Dawn arrives there – and at Ceres too. :-)

    Vesta is about 550 km (330 miles) across and clearly non-spherical.

    Hmm… I’d have said its boarderline sphereical~ish. Yeah, it’s not quite a sphere but I don’t thik its too far off. More a sort of lumpy sphere like a not-too smooth snowball or a dirty ball knocked out of shape with a bit of mud sticking to it. Also a lot of Vesta’s non-sphereicity is due to a huge crater taking a chunk out of it so it could be said to have a good excuse! It may not quite qualify for dwarf planet status but I don’t think it’s too far off and perhaps could be right on the boundary there.

  26. Pete Jackson

    Looks like Jason Voorhees to me! Fortunately, the only Friday the 13th this year has already passed, in May.

  27. Dutch Railroader

    Try this classic trick that can be done with rotation sequences. Cross your eyes to fuse the two side by side images into a 3-D image. You can see that the feature at 2 o’clock is a deep crater, and that the center of the image is a deep depression.

  28. Messier Tidy Upper

    @16. Doug : “Does anybody else see a face, turning to stare at the probe? Kinda freaky.”

    Yep. I see it. Pareidolia at work. ;-)

    @29. Pete Jackson : What’s wrong with 13? In our family that’s a lucky number. As Jim Lovell said in Apollo 13 “..it comes after 12.” Then again, that might not be the best example to use! ;-)

    @9. jamie :

    Didn’t know that it was so non-sperical. Previously thought that Vesta and Ceres should qualify as planets, but maybe not.

    I still think that Ceres at least should qualify as a planet – a small planet inside the asteroid belt so also the largest asteroid as well as the smallest planet – but a planet nonetheless.

    Ceres is certinaly a fair bit larger than Vesta (& Pallas too) and more notably sphereical than either of them. Of course Earth isn’t totally spherical and neither, for that matter, is Jupiter and there are other cases such as Haumea. I guess it depends how strict or generous you want to be on the departure from 100% sphereicity. Vesta to me, is right on the planet-asteroid border.

    Anyway, I personally doubt that there’ll anything terribly new or interesting to see there. All the other asteroids that we’ve examined have proven to be rather blah. Just big rocks.

    Sometimes big rocks can have big surprises in them and they can be fascinating and tell us a lot – ask any geologist or miner! ;-)

    Okay, asteroids may not float your boat but I think they’re pretty interesting and I suspect we may land on and make homes out of them one day – perhaps before we land on Mars.

    There are also very good reasons of planetary survival significance given the impact risks why we should try and understand the asteroids (& comets) better and learn as much as we can about them. Not all of them are the same, indeed Vesta is apparently cold-lava-covered
    whilst Ceres is icy and contains plenty of water. Interest like beauty is in the eye of the beholder. Curiosuity though is human and cries out tobe satisfied! ;-)

  29. Aaron: “…true science goes beyond the obvious appearances and digs as deep as it can go.”

    Yes, but there’s always a point of diminishing returns. We can’t expect every mission to be as spectacular as Cassini/Huygens or the Voyagers. Obviously, asteroids are far less interesting than eg. the Galilean satellites.

    “…we’ll definitely find SOMETHING new with this one…”

    Well, something new is likely, and maybe even *something* new, but I really doubt that we’ll see SOMETHING new. For that to happen, we’ll need to invest in a really expensive project, like a submarine for Europa, or a dirigible for Titan. I’m all for space exploration, but I do believe that we’ve now left the golden age of robotic probes (and I don’t expect much of a future for human exploration). The most exiting mission that’s coming up is the New Horizon mission to Pluto, but even then, it’s likely that Pluto will turn out to resemble Triton, only without the liquid nitrogen geysers.

  30. Messier Tidy Upper

    @ ^ jamie : Well I think youare being too pessimistic there – and remember Pluto has Charon and Nix & Hydra and perhaps rings too. What will it look like and what will we see & learn from NewHorizons and Dawn and other such missions – there’s only one way we’ll find out! ;-)

    @13. Brian : All these SF references in the comments, and nobody mentions “Marooned Off Vesta”?

    Well you did! ;-)

    Ah yes, the classics – for those who don’t get the ref – see :

    http://en.wikipedia.org/wiki/Marooned_Off_Vesta

    This lecture :

    http://www.youtube.com/watch?v=CVwRsAltFDw

    by Apollo 9 astronaut Rusty Schweickart is long (1 hour) but interesting or at least I found it so! ;-)

    But if you lack the patience, attention span and/or interest for that & if you want to see a short reason why we really should be studying these heavenly bodies though, this :

    http://www.youtube.com/watch?v=zxQSJj3pypA

    may have a bit of an impact! (A deep one even) ;-)

    *****

    PS. Yeah, I know that’s a comet – but an asteroid impact would be equally bad plus the categories do overlap somewhat and sometimes.

  31. IanS

    @31 Messier. “Ceres is certinaly a fair bit larger than Vesta (& Pallas too) and more notably sphereical than either of them. Of course Earth isn’t totally spherical and neither, for that matter, is Jupiter and there are other cases such as Haumea. I guess it depends how strict or generous you want to be on the departure from 100% sphereicity”

    The IAU definition that you so despise does not require sphericity, it requires hydrostatic equlibrium which in a spinning body is an oblate spheroid hence why the earth and jupiter qualify but Vesta doesn’t. Ceres as you well know is defined as a dwarf planet because it is in hydrostatic equilibrium whereas vesta clearly is not.

  32. RobT

    Was I the only one to first read that as On Approach to Vespa? Is the security code for NASA 12345? I was half-expecting to see a picture of MegaMaid on its way to the asteroid…

  33. @ Jamie:

    “Of what use is a child?” –Benjamin Franklin

    Trying to prejudge the outcome of any scientific endeavor is somewhat pointless.

  34. Messier Tidy Upper: “– there’s only one way we’ll find out!” Agreed.

    kuhnigget: I fully support NASA and robotic space exploration, and I look forward to seeing close-ups of Vesta. I’m merely pointing out the fact that we’ve reached a point of diminishing returns.

  35. Jamey

    Why so short a clip? I’m sure these nav camera frames don’t have near the resolution of the science cameras, so storage on the probe can’t be *THAT* full? Why not take enough of these to give us four or five full rotations? Use that to time things so that a long series, with the same face in the frame, could be taken so that the change in apparent size becomes obvious?

    Seriously – the same 20 frames (2 seconds, at cartoon frame rates) repeated 5 times, just doesn’t impress me that much.

  36. Dutch Railroader

    @38

    There is only one camera on Dawn, and it serves both science and navigation requirements. The camera further has pixels fixed at 19.4 arcseconds, which are huge; there is no zoom lens. In any case, I wouldn’t infer what or what not has been done, based on what the team has chosen to release.

  37. @34. IanS :

    @31 Messier. … The IAU definition that you so despise does not require sphericity, it requires hydrostatic equlibrium which in a spinning body is an oblate spheroid hence why the earth and jupiter qualify but Vesta doesn’t. Ceres as you well know is defined as a dwarf planet because it is in hydrostatic equilibrium whereas vesta [sic] clearly is not.

    Er .. IanS, did you miss the bit where that was pretty much exactly what I noted? :

    “Ceres is certinaly a fair bit larger than Vesta (& Pallas too) and more notably sphereical than either of them. Of course Earth isn’t totally spherical and neither, for that matter, is Jupiter and there are other cases such as Haumea. I guess it depends how strict or generous you want to be on the departure from 100% sphereicity”

    Note the bit in bold there? So yeah, I actually pointed that out and, of course, how does one define and work out what “hydrostatic equilibrium” means in plain english terms – basically it equals an object being round or rounded with a few ellipsoidal exceptions for objects like Haumea, Saturn or for that matter Achernar. (Alpha Eridani)

    I also noted that the extent to which something is in “hydrostatic eqilibrium” or how much of a departure from, “sphere-icity” you allow before drawing the line is a question. I’m not saying Vesta *does* qualify for planet status (I include dwarf planets as planets just as I include dwarf stars like our Sun as stars) only that it is perhaps *close* to qualifying, a borderline case.

    The reasons I despise the IAU definition of planet have nothing to do with the “hydrostatic equilibrium” criterion which I agree with (& which btw. Pluto, Eris, Ceres etc. pass) and much more to do with the unnecessary and illogical “cleared orbit” criteria which raises far more problems and questions than it resolves. Plus, as already noted, the exclusion of dwarf planets from planetary status is INCONSISTENT with the convention that “dwarf stars” (90% of all of them!) still count as proper stars!

  38. Gunnar

    I too am excitedly looking forward to see the close up pictures of Vesta, once orbit is achieved. I wonder, though, why Vesta was chosen before Ceres or Pallas as the first asteroid to send a robot probe to orbit around it. Are there plans to eventually send probes to Ceres and Pallas also?

  39. To be picky, both Eros and Itokawa have already been orbited by probes. Vesta is just the first of the Big ones, and orbital mechanics pretty much dictated Dawn going there before heading on to Ceres (a long enough journey that, IIRC, Pluto should become the first dwarf planet to get a closeup visit).

  40. Gunnar

    Yeah, I meant specifically the three big ones in the main belt. I forgot about Eros and Itokawa being orbited. I just looked up Pallas and found out why it is very unlikely to be orbited in our lifetimes. It is in an orbit that would be extremely difficult for us to reach and match with currently available spacecraft and technology.

    Thanks for your prompt reply to my question! :)

  41. FoxtrotCharlie

    YAWN. I already colonized the piece of rock in my boardgame High Frontier. I’m producing rare Salt-water Zubrin thrusters to sell in LEO.

  42. Pluto Animus

    I’d better get my amateur evaluation of the data before the professionals do….

    Based on the July 1 photo of Vesta from the Dawn Spacecraft:

    The massive bump on Vesta appears to be the remains of it South Pole, a huge amount of material stripped away by a collision with another large asteroid. Presumably, the core is mostly iron, which would be the large bump, while rock and other lighter material was blasted away. This bump appears to be about 60 miles in diameter and 25 miles tall.

    Another photo of Vesta appears to show an enormous peninsula-like formation. The scarps of this formation appear to be an astounding 15 to 20 miles high.

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