On March 17, just a month from now, NASA’s MESSENGER probe is scheduled to enter orbit around Mercury, the smallest planet in the solar system. No other mission from Earth has ever done this, and for the first time we’ll get high-resolution maps of the entire globe.

On its way down, the spacecraft was commanded to turn around and look outward, toward space. It took a series of images of what it saw… this astonishing family portrait of the solar system:

Click it to ensolarsystemate it and see it in more detail. When you do you’ll see the five classical planets in our system, as well as the Earth and Moon. Uranus and Neptune are there, but too faint to see, unfortunately, but still, this is an interesting picture. In November 2010, when these pictures were taken, Mercury was still nothing more than a dot. In fact, all the planets as barely more than dots, a reminder that this probe is well away from home and nowhere near any solid ground.

I like very much the images of Venus and the Earth. Venus is technically the closest planet to MESSENGER besides Mercury, though it depends on where the planets are in their orbits. It’s extremely bright as seen from the spacecraft, since MESSENGER is inside the orbit of Venus: the planet is therefore close to being full (like the full Moon) and reflects a lot of light back to the cameras.

And the Earth is accompanied by the Moon! That always amazed me. I’m so used to seeing pictures of just the Earth from space that it’s easy to forget that the Moon travels along with us. An important reminder in this picture is just how far the Moon is from us; 400,000 km is over 100 times the Moon’s size, so it appears to be a dot located well away from its home planet. If you wanted to make a scale model of it, a good way would be to use a golf ball to be Earth, and a marble located a meter away to be the Moon. That really brings home — ironically! — how small and distant our Moon is.

If you look to Jupiter you can see it has a couple of moons near it as well. The four moons spotted by Galileo 400 years ago are pretty big; Ganymede is actually about the same size as Mercury itself! Were Jupiter not there, Ganymede might be considered a planet on its own.

I smiled when I saw the section of the picture between Jupiter and Mars — that fuzzy glow is the Milky Way itself! The split down the middle is a dead giveaway; that’s caused by dust located in the disk of our galaxy. That section of the sky looks toward the center of our galaxy in the direction of the constellations Scorpius and Sagittarius.

I mention that last part on purpose. (more…)

Last week, the MESSENGER spacecraft passed the solar system’s smallest planet for the third and final time; when they next meet it won’t be some quick fling, it’ll be for a long term relationship.

Several gorgeous images were returned from the spacecraft, but this one is my favorite so far:

This is a large impact basin about 260 km (160 miles) across. It’s never been seen before! Only one other spacecraft has visited Mercury before — Mariner 10 in 1974 — and its orbit was such that it never did see many parts of the planet. MESSENGER was in the right place at the right time to snap this picture.

Note that it’s a double ringed crater. It’s not quite clear why these features form. It may be due to the forces generated upon impact, when a shock wave travels through the rock and rebounds inside the crater, or it may be from subsequent volcanic flows. Double rings are only seen in large impact events, so that must have something to do with it. You can also see concentric troughs or cracks in the crater middle. Those are due to the stretching of the crater floor after the impact.

Other images of Mercury from this third pass are just as cool: a bright splash around a double crater (seen here; most likely lighter material under the surface blasted out on impact), a crater with an elongated pit in its floor that makes it a pretty good smiley face, and a lovely shot of the northern limb of the planet spattered with craters.

I imagine they’ll release a handful more images over the next few days, but that’ll be it for the most part until March 2011, when MESSENGER meets up with Mercury one last time, settling into orbit… and then we’ll see lots more images. Lots and lots more… and they’ll be even higher resolution than these. What wonders will we see then?

The spacecraft MESSENGER is just three days away from its third encounter with Mercury. The past two have been nothing short of frakkin’ amazing, so I’m really looking forward to this final pass. Even though it was 1.3 million kilometers away from the tiny planet on the 25th, it snapped this serene shot:

I love moody astronomical pictures. Here, a crescent Mercury sits in the inky black as MESSENGER screams down on it at 3.3 km/sec (2 miles per second). ON this final pass, the spacecraft will slow enough that it will be able to enter orbit around Mercury in March 2011. The nominal lifespan of the mission will be for one solid (Earth) year of observations, and will map the planet with 18 meter resolution. That’s the size of a house.

That is so going to rock. But that’s 1.5 years away, and we’re still waiting on this third pass. I hope to be able to post pix when they come in, but I’m traveling to the UK for TAM London not long after, so we’ll see. But you can always keep an eye on the MESSENGER website, as well as Emily Lakdawalla’s blog. They’ll be up-to-date… especially, if I know her, Emily, who will be spending the flyby looming over her keyboard and hitting "refresh" every 30 seconds or so.

1) The new Carnival of Space is up at Lab Lemming’s tent, and it’s a BIG tent.

2) Emily has news that Phobos is a bit lighter than previously thought. What a pile.

3) Emily also has some nifty new MESSENGER images explained. I’ve been too lazy to deal with that.

4) Tom notes that HiRISE spotted Spirit on Mars. Massively embiggenated version is here.

4) This is dumb. So why did it make me smile so much? Oh right: I’m a dork.

I posted a few days ago that NASA’s MESSENGER probe is headed toward a rendezvus with Mercury on Monday. In the comments, BigBob noted that the first image has been returned!

This was taken on January 11, when the spacecraft was still 1.7 million kilometers from the planet. On Monday, it will pass about 200 km over the surface (yikes!). It will fly on, making two more passes of Mercury over time before settling into orbit, and making a detailed map of this planet. That’ll be in 2011, so the images we see from this first of three flybys will have to do you for now.