How NASA Uses the Full Moon to Calibrate Its Earth-Gazing Satellite

The full moon—like yesterday's glorious event—is a great show for us here on Earth. But for NASA, it also plays a critical role in keeping its Landsat 8 satellite working properly. How? By using the moon exactly like a photographer uses a light meter.

Landsat 8 is all about Earth: It's designed to image our planet for use by the government and us citizens. But once in a full moon, this little satellite pulls its gaze from its main priority and turns in a different direction: The moon. Because the full moon is so bright, it provides a chance for NASA's engineers to make sure Landsat is reading Earth's more patchy brightness levels clearly.

Because the moon has no atmosphere and a surface that's uniform, it's the most stable place for NASA to check Landsat against. Here's how PhysOrg describes the process:

The timing is set for just after the moon is completely full. Then, as Landsat 8 passes over Antarctica and heads north in Earth's shadow, the spacecraft maneuvers to the precise location to start the first scan across the lunar surface.

It executes tiny and precise scans to take seven or eight passes across the moon – each one angled so that a different detector is centered on the moon. This takes about 18 minutes, by which time the spacecraft has almost reached the Arctic.

So the moon, which is such a constant here on Earth, is also playing a role in keeping our exoplanetary concerns stable. [PhysOrg]

Image: KPG_Payless.