In 2007, the European Space Agency probe passed by Mars on its way to visit a comet. It used Mars for a gravity assist to help it on its way, and got close enough to take some very detailed pictures (it also passed by the asteroid Lutetia and returned amazing shots; see the gallery at the bottom of this post). That data wasn’t initially released by the mission leader (that’s fairly common in some missions), but they were finally made available late last year. My pal Emily Lakdawalla from the Planetary Society Blog grabbed a bunch of them and put together some simply amazing pictures from them, including this jaw-dropper:

Yeah. You really want to click that to Barsoomenate it. Holy dry ice polar caps!

In fact, you should go over to her blog where she gives all the details and has more incredibly cool pictures of the Red Planet as well. I don’t want to spoil her fun by giving it all away here. Go!

Credit: ESA / MPS / UPD / LAM / IAA / RSSD / INTA / UPM / DASP / IDA / processed by Emily Lakdawalla

- Rosetta’s cometary goal now in sight
- Lutetia may have witnessed the birth of the Earth
- Curiosity on its way to Mars!

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When we look at the solar system now, we see it after it’s had billions of years of evolution under its belt. Things have changed a lot since it first formed out a swirling disk of material, 4.5 billion years ago. We can make some pretty good guesses about the way things looked back then, though. We can see other systems forming around other stars, for example, to get an idea of what things look like when they’re young.

But we can also look at our own solar system, look at the planets, the comets, the asteroids, and, like astronomical archaeologists, get a glimpse into our own cosmic past.

We know that asteroids formed along with the rest of the system back then. We also know that there are many kinds of asteroids: rocky, metallic, chondritic, some even have ice on or near their surface. Some formed far out in the solar system, and some formed near in. The thing is, we think the vast majority of the asteroids that formed close to the Sun were absorbed by — and by that, I mean smacked into and became part of — the inner planets, including Earth. Only a handful of those asteroids still remain intact after all this time. But now we think we’ve found one: the main belt, 130 km-long asteroid Lutetia.

Using a fleet of telescopes, astronomers carefully measured the spectrum of Lutetia — including spectra taken by the European Rosetta space probe, which visited Lutetia in July 2010 and returned incredible close-up images (see the gallery below). The spectra were then compared to spectra of meteorites found on Earth — meteorites come from asteroids after a collision blasts material from them, so they represent a collection of different kinds of asteroids that we can test in the lab here on Earth.

They found that the spectrum of Lutetia matches a very specific type of meteorite found on Earth, called enstatite chondrites. These rare rocks have a very unusual composition that indicates they were formed very near the Sun, where the heat from our star strongly affected their formation. They have a clearly different composition than meteorites which formed in asteroids farther out in the solar system, and are an excellent indication that Lutetia formed in the inner solar system, in the same region where the Earth did.

So Lutetia is a local! There aren’t many like it in the asteroid main belt between Mars and Jupiter, and in fact it’s a bit of a mystery how it got there; perhaps a near encounter with Earth or Venus flung it out that way, and then the influence of Jupiter made its orbit circular. And there it sits, a relatively pristine example of what the solar system was like when it was young. Currently, the Dawn space mission is orbiting the large asteroid Vesta, and will make its way to Ceres, the largest asteroid, after that. I have to wonder if NASA is eyeing Lutetia as another possible target. It’s an amazing chance to visit an object that may yield a lot of insight into our own planet when it was but a youth.

After all, you can take the asteroid out of the inner solar system, but you can’t take the inner solar system out of the asteroid.

Image credit: ESA 2010 MPS for OSIRIS Team. MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

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Rosetta is an amazing probe launched by the European Space Agency. In 2014 it will go into orbit around the comet 67P/Churyumov-Gerasimenko, and actually deploy a lander to sample the surface!

That rendezvous is still years away, but the target is now in sight: Rosetta has returned its first image of the comet.

Oh, very cool! The top image is the wide angle shot, showing a densely-populated star field toward the center of our galaxy; from Rosetta that’s the direction to the comet. The second image zooms in a bit, and you can see some distant stars and nebulosity. The bottom one has been processed to remove the stars, and the nucleus of Churyumov-Gerasimenko stands out.

Note that this image was taken when Rosetta was still 163 million kilometers (100 million miles) from the comet — that’s more than the distance from the Earth to the Sun! That’s why it took a total of 13 hours of exposure time to see the comet in these images; it’s still extremely faint from that great distance.

(more…)

On March 24, the NASA mission Stardust ran out of fuel and sent its last data to Earth. At 16:33 Pacific time the mission was officially ended.

Launched in 1999, Stardust became a wildly successful mission. It passed by the asteroid Annefrank, sampled the dust from one comet (Wild 2) — returning those samples to Earth in a special re-entry container while the spacecraft itself flew on — and looked closely at another (Tempel 1) to see the crater left by the Deep Impact mission.

It’s always sad to see a mission end, but I like to also keep my eyes ahead. Stardust may be done, but Rosetta flies on, heading toward a rendezvous with a comet where it will deploy an actual lander. The Dawn spacecraft will enter orbit around the main-belt asteroid Vesta later this year as well. And, of course, MESSENGER is now orbiting Mercury and returning data.

We learned a lot from Stardust, and we get better with this endeavor of solar system exploration as a result.

And that’s the whole point, isn’t it?

Image credit: NASA/JPL-Caltech

Use the thumbnails and arrows to browse the images, and click on the images themselves to go through to blog posts with more details and descriptions.

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Emily Lakdawalla — scientist, blogger, and all around cool chick — has just posted a totally awesome scale diagram comparing every asteroid and comet visited by spacecraft. It features pictures of all the rocks, each of which she has carefully resized so you can see just how big they are relative to each other:

Whoa. Look how big Lutetia, just visited by Rosetta, is compared to everything else! And yet, at 130 km across, it’s a dot compared to our Moon. In fact, you could smash together all the known asteroids in the main belt between Mars and Jupiter and they’d be far smaller than our rocky satellite.

Still, small doesn’t mean "uninteresting". These rocks in Emily’s diagram are all fascinating beasts, and the more we learn about them the more compelling they become. And there’s more to come, with the Dawn mission about to see the big asteroids Vesta and Ceres up close… and go read Emily’s blog about this to see how they’d fit on the diagram (hint, they don’t, and by a long shot). You’ll also find a much larger version of the diagram there, and you really, really should look at it. Wow.

The European space probe Rosetta passed about 3000 km from the asteroid Lutetia on Saturday, July 10, 2010, and it sent back incredible closeup images of the rock. Check ’em out below!

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Emily Lakdawalla at the Planetary Society Blog has more details, as always.