Fobos/Grunt is falling!

Seth Jarvis

You think living on Mars would be dangerous and difficult? Try just getting there!

Of the 38 Mars mission launched from Earth so far, exactly half of them arrived at Mars in operating condition.

A case in point is the Russian “Fobos/Grunt” (in English we would call it “Phobos/Soil”) mission launched last November that was intended to land on one of Mars’ moons, Phobos, scoop up some surface material, and then rocket the sample back to Earth. Total round-trip time: three years.

Sadly, just a couple of hours after launch the rocket motor that was supposed to send Fobos/Grunt from low Earth orbit to Mars failed to fire and ground controllers lost contact with the spacecraft.

Fobos/Grunt is now a derelict fourteen-ton spacecraft in a deteriorating orbit, destined to burn up in the atmosphere sometime between now and Monday.

The Fobos/Grunt Spacecraft - now just so much junk.

The Fobos/Grunt Spacecraft - now just so much junk.

Most of the spacecraft’s mass is its eleven tons of fuel. True, that’s a lot of toxic chemicals, but the fuel will most likely vaporize quickly very high in the atmosphere upon reentry.

Only about three tons of actual hard metal will survive the initial 18,000 mph encounter with our atmosphere, and only about 400-500 pounds of the spacecraft is expected to survive the fiery reentry and make it all the way to Earth’s surface.

There is almost zero chance that Fobos/Grunt falling from the sky will injure anyone or cause damage. After all, three-quarters of the world is covered by oceans, so right there you see there’s only a one-in-four chance of the spacecraft even hitting land.

Earth is a big place, and humans represent a teensy-tiny portion of the surface area. The chances of a piece of Fobos/Grunt hitting a human being are on the order of one in a thousand, and the chances of you being hit are something like one in million-million.

Update: Fobos/Grunt fell harmlessly into the southern Pacific Ocean at about 10:45 MST on Sunday, January 15, about 600 miles west of Chile. See? Told ya.

This phenomenon of dead satellites in low-Earth orbit creating problems for us is the subject of Clark Planetarium’s next ATK IMAX theatre documentary film. It’s titled, appropriately enough, “Space Junk 3D.” We’ll have more information about this film later in the month.

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One thought on “Fobos/Grunt is falling!

  1. Pingback: “Space Junk” is falling in the ATK IMAX Theatre « Clark Planetarium

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