Postcards from Clementine

This article originally appeared as a guest post on The Planetary Society’s web site.

Nineteen years ago this month, the Clementine mission arrived at the moon. A joint project of NASA and the Department of Defense, Clementine’s goals focused on testing lightweight sensors and other deep-space technology demos—but the results reached far beyond that. Besides several technical accomplishments, the mission returned a complete map of the moon, images of the Earth, and confirmed the existance of lunar water ice.

Compared to the instruments on current spacecraft, Clementine’s images were relatively small and low resolution. But a search through the raw data reveals some hidden gems. Here are some of my favorite postcards that the intrepid robotic explorer sent home.

The orbiter carried geologic mapping cameras, which let us see some lovely landscapes.

The Sea of Cleverness on the moon
The Sea of Cleverness – The Clementine orbiter captured this strikingly textured image of Mare Ingenii, “The Sea of Cleverness” on the lunar far side. I’ve stretched the contrast slightly and removed some very small seams in the image. Credit: NASA / Naval Research Laboratory / Bill Dunford
crater rays on the moon
A Splash of Rays – An unnamed rayed crater on the lunar far side, near Mandel’shtam Crater. The Clementine orbiter captured this dramatic image using its UV/visual camera.
NASA / Naval Research Laboratory / Bill Dunford

Clementine also relied on small, very lightweight (300-gram!) star tracker cameras to help it navigate, a modern version of a sailor with a sextant. It turned out that these navigational aids delivered some of the most amazing images of the entire mission.

the moon eclipses the sun

An Eclipse by Earthlight – The Clementine lunar orbiter sees the solar corona as the moon eclipses the sun. The moon is partially illuminated by reflected Earthshine. Credit: NASA / Naval Research Laboratory / Bill Dunford

The star trackers returned small files, but sometimes they contained some pretty amazing views.

observe the moon as it passes in front of the sun
The Moon in Motion – The Clementine lunar orbiter uses one of its star tracking cameras to observe the moon as it passes in front of the sun. Credit: NASA / Naval Research Laboratory / Bill Dunford

In one dramatic case, the heavens aligned so that Clementine could see the moon eclipsing the sun as the planet Venus shone brilliantly in the same scene.

The Moon, the Sun, and Venus
The Moon, the Sun, and Venus – This is one of the most widely-seen images from the Clementine mission to the moon in the 1990s: the Moon eclipsing the Sun, with the planet Venus shining brightly nearby. Credit: NASA / Naval Research Laboratory

While the picture above that NASA published is one of the most famous images from the mission, it’s by no means the only one the spacecraft sent down. Here’s another take. Below is a different frame from the same sequence of images. I’ve stretched the contrast of the raw image a little, but unlike the more famous picture, I’ve chosen to leave the ‘sparkle’ created by Venus dazzling the sensor.

The Moon and the Evening Star
The Moon and the Evening Star – One of the star tracker cameras onboard the Clementine orbiter captured the moon and Venus, which was so bright it somewhat overwhelmed the image sensor. Credit: NASA / Naval Research Laboratory / Bill Dunford

Clementine may not be the most celebrated deep space mission of all time, but it was an important stepping stone. And the stories it left behind are amazing even now.

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