I like meteorites. Each arrives on Earth with a flash and bang after millions of years of space travel from the asteroid belt. And just like that, a space rock that would otherwise require a $150-million-dollar mission to snatch falls into our lap. Face to face with an emissary from 4.56 billion years ago, we’re rocketed back into the remote past to a time before the first living cell on planet Earth.
Rocks routinely plop down on all the planets though we’ve only ever identified meteorites on Earth and the moon — where people pick them up — and Mars, where rover cameras see them. On Nov. 26, NASA’s Curiosity rover ChemCam, a camera mounted on a robotic arm that takes close-up photos of rocks, soil and other Martian surface features, snapped images of a shiny rock in Gale Crater that appears to be an iron meteorite. They’ve even given it an the informal name of Little Colonsay“, after an uninhabited island in Scotland. It has a distinctive metallic sheen typical of iron meteorites and probably measures a few inches across. Notice how fresh it looks.
On Earth, oxygen and water attack all meteorites as soon as they land. Many contain pure iron-nickel metal either as pepper-like flecks, nodules and soon begin to rust. If an iron meteorite fell in Duluth, Minn. it would start showing signs of rusting within days, but on Mars, where there’s zero rainfall, routine subzero temperatures and an atmosphere that contains just 0.13% oxygen (Earth is 21%), meteorites stay rust-free for a long, long time.
On November 29, the second half of the ChemCam instrument called the LIBS (laser-induced breakdown spectroscopy), zapped the rock three times with an invisible (to our eyes) infrared laser, vaporizing bits of the material and burning tiny pits in its surface. The vapor was analyzed by a spectroscope that can read the signatures of chemical elements in the evanescent cloud of rock plasma to determine its composition. If there’s a lot of iron and nickel present, scientists can safely say they’ve found a Martian meteorite.
It won’t be the first. Between 2005 and 2018 six meteorites — all irons — have been discovered by rovers and their science teams on Mars. The first, Meridiani Planum, was discovered by the Opportunity rover on Jan. 5, 2005 and measured 12.2 inches across (31 cm). There are different types of iron meteorites, but this one turned out to be the same as the famous Canyon Diablo meteorite found at Meteor Crater near Flagstaff, Arizona.
We don’t know yet whether this latest find is a meteorite, but when we do, I’ll update the blog. Do stop back.
In other Mars news, NASA’s InSight lander successfully made it to the surface of the Red Planet and has started taking photos, a few of which you can check out at this link. The vehicle sits at a slight 4° tilt in a shallow dust- and sand-filled impact crater known as a “hollow” on the lava plain called Elysium Planitia. Mission control is very happy with the location, which they say is like a very large sandbox without any large rocks that might get in the way of setting up sensing instruments.
Once sites on the Martian surface have been carefully selected for the two main instruments, the team will open up and begin initial testing of the mechanical arm that will place them there. More on this soon!