NASA Celebrates New Year By Putting Moon Gravity Probes In Orbit

The New Year got off to a great start for NASA as it managed to put the twin GRAIL probes in an orbit around the Moon. They are now set to beam each other radio signals, which will keep them synchronized in orbit and the distance from one probe to the other can be known to an error margin or a micron!

The GRAIL probes, before they were launched (Courtesy: NASA)

Measuring the gravity of the situation

The GRAIL probes are designed to accurately measure the Moon’s gravitational field strength. The technique is pretty simple really! When one of the probes passes close to a lunar region, which has high density, it will feel a greater gravitational pull. This will suddenly accelerate the probe and the distance between the two probes will decrease. This is how the density map of the moon can be prepared. Of course, it’s never as easy as this, is it?

Why map the moon anyway? The gravity map of Earth’s closest satellite can give us a good map of the composition of the moon. One of the mysteries that might be solved is why the two faces of the Moon look so very different; one is rolling flatlands, without any craters, while the other one is puckered with numerous craters.

The GRAIL probes will now descend and sink lower into its orbit, getting closer to the Moon’s surface. The data acquisition is supposed to start early March, when the probe is 34 miles above the lunar surface.

Getting young minds into the project

One of the best things about this mission is the attempt to get students into this thing. As Phil Plait writes in his blog, Bad Astronomy, there will be four cameras on each of the probes, called MoonKAM. These will get high resolution photos of the lunar surface and these can be used by middle school students. They may even request NASA to fly the probes over a particular area on the Moon. As Phil Plait puts it:

That’s very cool! … I’ll bet it’ll be an experience they’ll remember their whole lives.

I’m sure too! Being part of science is sometimes being like a detective, without the dirty work!

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Debjyoti Bardhan

Is a science geek, currently pursuing some sort of a degree (called a PhD) in Physics at TIFR, Mumbai. An enthusiastic but useless amateur photographer, his most favourite activity is simply lazing around. He is interested in all things interesting and scientific.