The European Space Agency’s Mars Express is one of more than 20 spacecraft now exploring planets or moons in our solar system. On January 9, 2011, the craft flew past the martian moon Phobos and captured new images from a distance of only 100 kilometers (60 miles). Here are three that I found particularly intriguing, for different reasons.
The image at right shows previously planned (red) and currently considered (blue) landing sites for the planned Russian mission Fobos-Grunt (meaning “Phobos Ground”). It’s a sample return mission to Phobos, scheduled for launch late 2011 or early 2012.
It’s exciting to see this type of mission actually happening, because, for decades – both in science fiction and in real space science – Phobos has been considered as a possible way station for manned explorations of Mars. The reason is that little moon orbits close to Mars – only 9,400 kilometers (5,800 miles) above the red deserts of Mars. That’s in contrast to 400,000 kiometers from Earth to our moon. So you see Phobos is an ideal landing spot, prior to a Mars landing. Landing on it would be easier and less expensive than a landing on Mars itself. Remember, a lander bound for Mars – perhaps with human beings aboard – would have to enter Mars’ atmosphere and later return to orbit, without any support facilities on the ground. This has never been attempted in a manned spacecraft. Or Mars astronauts would have to build support facilities in-situ (“colony or bust”).
Meanwhile, we’ve already had spacecraft land on and return from the moon and asteroids. A Phobos landing could use similarly designed equipment. So the Russian landing on Phobos is a possible first step to a human presence on Mars. I’m not saying I favor that in the near future, but it’s interesting to contemplate how it might be done.
So human exploration of Phobos could serve as a catalyst for the human exploration of Mars. It would also be exciting and scientifically valuable in its own right, and that brings us to the second recent image from Mars Express, at left, again taken on January 9. See the streaks on Phobos in this image? Now look at the far right side of the image at right to see that this martian moon isn’t perfectly round. There’s a chunk taken out of one side, like an open mouth. This is a crater – the biggest on Phobos. It’s a six-mile wide impact crater called Stickney, named for Chloe Angeline Stickney Hall, wife of Asaph Hall. who discovered the two martian moons Phobos and Deimos in 1878.
Spacecraft were needed to discover Stickney, which you can see from a better angle in the mosaic image at right. This image was taken by the Viking 1 spacecraft in 1978. It’s really three images pieced together. Besides showing Stickney, it also gives you a chance to compare Mars Express’ super clarity with the blurriness of earlier Viking 1 images.
You can see that Stickney dominates one whole side of Phobos. The crater is thought to be the result of an ancient impact that nearly destroyed this little martian moon. The impact is thought to have caused the streaks we see in the Mars Express image above – much as a baseball from an errant pitch will cause streaks to radiate from the point of impact on a car’s windshield. Other lines on Phobos might be the result of landslides down the steep sides of Stickney. Nature in action.
The image at left is another Mars Express image taken on January 9 of this year. It’s a 3-D image. If you squint, you can see the 3-D-ness of it. Cool, yes?
The Mars Express spacecraft is a project of the European Space Agency. It left Earth in mid-2003 and went into orbit around Mars on Christmas Day, 2003, Mars Express ejected a lander called Beagle 2 (named for Charles Darwin’s ship The Beagle), Unfortunately, the Beagle 2 lander was declared lost after it failed to make contact with orbiting spacecraft and Earth-based radio telescopes. The Mars Express orbiter, however, has been moving around and around Mars ever since. You can find out more about it here.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.