Tag: Phobos

Animated transit of a Martian moon

By Phil Plait | October 16, 2012 9:00 am

Back in September I posted an image taken from the Curiosity rover showing Phobos, one of the moons of Mars, crossing the face of the Sun.

That was pretty cool. But this is cooler: video of Phobos transiting the face of the Sun seen from the rover Opportunity on September 20, 2012!

Lest it be overshadowed (HAHAHAHA! Get it?) by Curiosity, remember Opportunity is still going strong after more than eight years on the surface of the Red Planet. These shots from the elder rover are really awesome; Phobos is not even close to being a sphere and you can see its potatoey lumpiness in the animation.

Phobos is about 27 km (17 miles) across its long axis, which is small for a moon. It looks big because it orbits Mars so close in; it’s only 6000 km above the surface. It was actually a bit farther away from Opportunity when these images were taken, making it look smaller than it could be.

In fact, given its size and distance, Phobos has a maximum size in the sky of about a quarter degree, or half the size of our full Moon. As seen from Earth, the Sun and the Moon are about the same size in the sky. But Mars is farther from the Sun, so the Sun looks smaller, about 1/3 of a degree. So even at best Phobos can’t completely block the Sun.

But… Phobos isn’t in a stable orbit. Tides from Mars are dropping it down closer to the planet, making it appear bigger. In a few million years it’ll drop low enough to create total eclipses as seen from the surface of Mars. They won’t last long, since the moon is zipping along pretty rapidly in its orbit. Still though, I have to admit to a bit of delight: creationists like to claim the Earth is special, and we’re the only planet that has the right conditions for total solar eclipses. That’s not even really true right now, and it certainly won’t be once Phobos dips down a bit more.

Of course, once Phobos gets too close to Mars a few million years later it’ll crash into the surface, making the sweatiest apocalyptic scenarios dreamed up by humans look like a warm summer’s breeze by comparison. Nature! It has a way of making our fevered imaginations look like pretty small potatoes.

Image credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ. Tip o’ the rocket crane to Mars Curiosity on Twitter.


Related Posts:

A solar eclipse… FROM MARS!
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More *incredible* Phobos imagery

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

A solar eclipse… FROM MARS!

By Phil Plait | September 15, 2012 12:34 pm

OK, this is simply too cool.

The Mars Curiosity rover has already returned thousands of images taken of the Red Planet’s landscape. But on September 13, 2012, it was commanded not to look around, but to look up, at the Sun. Why? Because Mars’s tiny moon Phobos passed directly in front of the Sun, partially eclipsing it!

Sweeeeet. I blew the original image up by a factor of two for clarity.

Technically, this is called a transit – when a much smaller body passes in front of a larger one. Usually, there’s some science that can come from this; the timing of the transit gives a better orbit for the moon (since the rover’s location on the surface is precisely known), and so on. In this case, though, we study Phobos with other orbiting spacecraft, so I’d think its orbit and position are extremely well determined.

It may very well be that this shot was taken just because it’s cool. I actually kinda hope so.

It’s not the first time a Phobos transit has been seen; in fact it’s been done several times. Here’s a video of one seen by the rover Opportunity in November 2010:

Wikipedia has more info. I’ll note that as of right now, the image above is the only one I’ve seen listed on the Curiosity raw images page (at decent resolution, that is; there are lots of tiny thumbnails, and bigger, cleaner versions should show up soon). The image was taken by the MASTCAM, which has a filter on it so it can observe the Sun. It does that for various reasons, including being able to observe how much the Martian atmosphere is absorbing sunlight.

Phobos orbits Mars pretty close in, just about 6000 km (3600 miles) above the surface of Mars – compare that to the 400,000 km distance from the Earth to the Moon! Phobos is so close that it transits the Sun pretty much every day for some location on Mars, making this something of a less-than-rare event. It’ll only be a year before it happens again at Curiosity’s location.

Still. It’s an eclipse, seen from Mars, taken by a nuclear powered one-ton mobile chem lab that we put there. I think that qualifies as pretty damn cool.

Image credit: NASA/JPL-Caltech/Malin Space Science Systems. Tip o’ the heat shield to… MarsCuriosity on Twitter!


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ESA writes off Phobos-Grunt

By Phil Plait | December 2, 2011 2:07 pm

The Russian space probe Phobos-Grunt was an ambitious attempt to send a spacecraft to Mars, land on its moon Phobos, and return a sample to Earth. However, once it achieved low-Earth orbit after launch in November, the rocket that would have sent it on its way to Mars failed to fire, stranding the probe here at Earth. There have been numerous attempts to communicate with Phobos-Grunt, but they have been met with very limited success and most usually failure.

And now another nail has been driven in the coffin: the European Space Agency, which was tasked with spacecraft communications during the cruise phase to Mars, has announced they will no longer try to talk to Phobos-Grunt, declaring the mission "no longer feasible". Ouch.

NASA joined in the effort to talk to the probe, but had to abandon those efforts when the antennae were needed for other missions. It’s unlikely Russia will give up on the mission soon, but my own opinion is that the outlook’s pretty bleak. If they can’t get the probe on its way, or even boosted to a higher orbit, it’ll burn up in an uncontrolled re-entry over Earth sometime in February. The Russians are saying the fuel onboard will burn up as well and shouldn’t pose a threat to people on the ground. I expect we’ll be hearing more about that as time goes on.

I’ll note that Curiosity, NASA’s Mars Science Laboratory rover, launched successfully recently and is looking good as it heads to Mars, so there’s that.

As usual, you should follow Emily Lakdawalla on her blog and on Twitter for current info on all things involving planetary space missions.

CATEGORIZED UNDER: NASA, Space
MORE ABOUT: ESA, Phobos, Phobos-Grunt

Phobos-Grunt scheduled to launch at 20:16 UT

By Phil Plait | November 8, 2011 9:05 am

[Update (20:30 UT): The mission launched on time, and everything looks good so far! As I write this, the probe’s orbiting the Earth. In a few hours (a little after 01:00 UT) it will make its burn to send it on its way to the Red Planet. Congrats to everyone involved in this mission!]

[UPDATE 2 (05:00 UT): There are problems, potentially serious ones, with the mission. As I write this what happened is not clear, but Emily is keeping up with the news.]

[UPDATE 3 (Nov 9, 16:00 UT): It looks like the spacecraft is in safe mode, meaning it shut itself off to prevent damage due to an unforeseen problem. The burn to move it out of Earth orbit and no to Mars did not occur, which means it still has all its fuel. This is very bad, but perhaps not catastrophic. Emily has the details.]

The Russian Mars probe Phobos-Grunt — which will land on the Martian moon Phobos and return a sample to Earth! — is scheduled to launch today at 20:16 UT (15:16 Eastern US time). As usual with planetary missions, Emily Lakdawalla has the details. The launch will be streamed live on SpaceflightNow.

phobos_hires

Grunt means "soil" in Russian; the name is a little misleading since soil technically is rock and other material broken down in part by bacterial processes. A better term is regolith, but I’m just being pedantic. The important thing to note is that if all goes well this probe will return a sample of the surface of another planet’s moon back to Earth!

That’s awesome.

We still don’t understand Phobos all that well; it may be a captured asteroid orbiting Mars, and its surface is weird, as you can see in the picture above. It’s lined with grooves, which may have formed when asteroid impacts on Mars below blasted up material, which the tiny rock then plowed through. That’s still being argued about. A sample return might help resolve issues like that (for example, finding clear evidence of Martian minerals in Phobos samples). I’m not a geologist, or an asteroid expert, so I’m just excited that a) this probe is going to get intense images of Phobos, 2) we’re going to expand the boundaries of science once again, and γ) there will be even more new mysteries to solve once the material is studied, too.

And it all starts today, in a few hours.

Credits: ESA/DLR/FU Berlin (G. Neukum)


Related posts:

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CATEGORIZED UNDER: Astronomy, Cool stuff
MORE ABOUT: Mars, Phobos, Phobos-Grunt

Phobos passes Jupiter… as seen from Mars!

By Phil Plait | June 17, 2011 12:40 pm

Mars Express is a European Space Agency probe that’s been orbiting the Red Planet since 2003, returning vast amount of data. Lately it’s been taking some amazing images and video of the tiny Martian moon Phobos, and the ESA just released this amazing footage of the lumpy potato moon passing by Jupiter as seen from the orbiting craft:

How cool is that? Engineers saw this viewing opportunity and actually changed the orbit of Mars Express to be able to see it. Phobos passed a mere 11,400 km (6800 miles) away when these shots were taken, but Jupiter was 530 million km (320 million miles) in the background. That’s why a moon only 27 km (16 miles) across can appear to dwarf a planet 140,000 km (86,000 miles) across! In the diagram here, the relative positions of all four players is shown; click to enbarsoomenate.

Read More

Phobos is, like, totally groovy

By Phil Plait | January 24, 2011 7:00 am

As recently promised, the European Space Agency’s Mars Express probe made a very close pass of the small moon Phobos, taking incredibly detailed pictures of the spud-shaped rock. Emily Lakdawalla, as always with planetary missions, has the what-fors with this event.

When it was a mere 111 km (66 miles) from the moon, Mars Express took this amazing image:

Click it for the full-res version is a whopping 7800 x 5200 pixel, 13 Mb TIF barsoomenated version. The detail is incredible, with features as small as 8 meters (roughly 25 feet across). Since Phobos is about 27 km (17 miles) long, that’s a lot of detail!

But as regular readers know, I have a thing for 3D red/green anaglyphs, and as the probe passed the moon naturally took stereoscopic images. The folks at ESA put two together to make this jaw-dropping 3D shot of Phobos:

Click it to get 3800 x 2600 pixel, 13 Mb TIF version. You really want to. If you have red/green glasses, this is one of the best anaglyphs from space you’ll see. I’ve never seen something stick out of my screen like this! Also, the details were so sharp that if I shake my head back and forth (like gesturing "no") I can actually see Phobos rotate a little bit, due to the change of positions of my eyes! That was new to me as well, and is very cool. it really solidifies the illusion that you’re seeing an object three-dimensionally.

Mars is an astonishing place, and it’s easy to forget how interesting its two moons are (the other is Deimos, which is smaller than Phobos). Their origins are still something of a mystery, and the surface features on Phobos are not totally understood either. Read More

CATEGORIZED UNDER: Cool stuff, Pretty pictures, Top Post

It's rabbit^h^h^h Phobos season!

By Phil Plait | January 12, 2011 7:00 am

The European Space Agency probe Mars Express has been orbiting the Red Planet for just over seven years now, returning vast amounts of information. It looks at Mars, of course, but also the two dinky and weird moons Phobos and Deimos. For example, a little while back it took this phenomenal shot of Phobos over the limb of Mars:

[Click to greatly barsoominate.]

That’s fantastic! Note how dark Phobos appears; it really is much less reflective than Mars. Its origin is unclear, but a popular idea is that it’s an asteroid Mars captured long ago. I’ve never been comfortable with this idea, since capturing an object is extremely difficult. An asteroid moving past a planet will just fly on by unless it is slowed considerably, and there aren’t many ways to do that. If it passes extremely close, the atmosphere of the planet might slow it sufficiently, but that results in a highly elliptical orbit that’s unlikely to last very long. Perhaps Phobos was a binary asteroid, and one of the two components absorbed the extra energy and was ejected, while the other settled into orbit and became Phobos. Maybe it got its start in some other way entirely.

We’ll hopefully learn more when the Russian probe (and lander with sample return!) Phobos-Grunt launches later this year. In the meantime, Mars Express is in an orbit that periodically brings it close to Phobos several times, and we’re entering a new season of passes right now. In fact, it just had a close encounter with Phobos, and word has it the flyby was a success! That means we’ll soon be getting more even interesting and beautiful images of this enigmatic little moon, so keep your eyes open for them.


Related posts:

More incredible Phobos imagery
Phobos: closeup of fear
Deimos!
The shadow of a moon goes passing by


CATEGORIZED UNDER: Astronomy, Pretty pictures

The shadow of a moon goes passing by

By Phil Plait | December 15, 2010 2:00 pm

The Viking 1 space probe settled into orbit around Mars in 1976, dropping a surface lander in the process. The probe stayed in orbit to monitor the planet, returning thousands of pictures from millions of kilometers away.

Those pictures are sitting in an archive, and sometimes have hidden jewels in them. As Emily Lakdawalla reports, somehow the keen-eyed Daniel Macháček spotted an amazing thing: the shadow of the Martian moon Phobos passing over a dust storm:

Wow! This animation is sped up by a factor of 10, and you can see the tiny moon’s shadow slip across the face of the planet. He also has one sped up 40X, and there you can see the slow movement of the dust storm, too… though it’s only slow due to distance; I’m sure someone standing on the surface would laugh ruefully at describing the 100 km/hr gusts as "slow". If they could breathe, that is.

Anyway, Emily has more information on the animations. I think this is amazing work, and we’ll be seeing more things like this as the planetary (and astronomical) databases get plumbed by the public. A lot of folks out there are very talented at digging out treasures, and equally adept at creating beautiful imagery and animations, too.


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CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

More *incredible* Phobos imagery

By Phil Plait | March 31, 2010 7:32 am

I’ve already posted some beautiful closeups of Phobos, a moon of Mars, taken by the Mars Express space probe, after the European Space Agency aimed the spacecraft at the tiny moon. The closeups are beautiful, but now the ESA has posted a stunning full-body shot of Phobos:

phobos_hires

[As usual, click the pix to embiggen.]

The resolution is an amazing 9 meters (30 feet!) per pixel. Clearly, Phobos has been through a lot. Mars orbits near the inner edge of the asteroid belt, which may explain how battered its surface is. The grooves were once thought to be ripples from a big impact that created the whopping crater Stickney (not seen in this view, but you can see it really well here), but are now thought to be from boulders rolling around in the low gravity of the moon, perhaps ejected rocks from various impacts landing back down in the feeble gravity.

Note the one winding path going from the upper left to lower right: that looks very much like a boulder bounced its way across the surface! The curvy path is an indication of the changing gravity field of Phobos: it’s not a smooth sphere, but a lumpy potato, so the surface gravity — what you’d think of as "down" if you were standing there — changes greatly depending on position.

phobos_anaglyphThey also put together this stunning 3D anaglyph. You can really see the depth of the craters and grooves on the surface. Run, don’t walk, to get a pair of red/green glasses for this one! Phobos really pops out of the screen. The depth and clarity of the 3D is amazing!

This pass of the moon was designed to obtain as much scientific data as possible before the launch of the Russian mission called Phobos-Grunt, which will land on the moon and send a sample of its surface back to Earth for study. Phobos looks an awful lot like an asteroid itself, and its origin is still something of a mystery. More data like these — and obtaining a sample of its surface material! — may clear up its story once and for all.

Credits: ESA/DLR/FU Berlin (G. Neukum)

CATEGORIZED UNDER: Astronomy, Pretty pictures

Phobos, closeup of fear

By Phil Plait | March 15, 2010 3:35 pm

As I promised a little while back, the European Space Agency has released new extremely high-res pictures of Phobos, one of the moons of Mars! Check this out:

ME_phobos

Yegads. Click to embiggen, and see this in all its glory. This image, taken by the Mars Express spacecraft, has a resolution of 4.4 meters per pixel, meaning objects about the size of a two-car garage can be seen on the surface of Phobos. For comparison, this lumpy, battered moon (named for the Greek word for fear, a companion to Mars) is 27x22x19 kilometers (16x13x11 miles), so even though it’s on the tiny side, this is still a fantastic map of the surface.

And an important one as well: next year, Russia will be launching a probe called Phobos-Grunt (Phobos soil) that will attempt to land on the moon, collect a sample of its surface, and send it back to Earth! These images of Phobos will help the Russians figure out the best place to land.

On the ESA page linked above, you’ll also find a cool 3D anaglyph of Phobos, and if you want to stay up to date on all this, check out the Mars Express blog, too.

Image credit: ESA/DLR/FU Berlin (G. Neukum)

CATEGORIZED UNDER: Astronomy, Pretty pictures, Space
MORE ABOUT: Mars, Mars Express, Phobos
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