From 56 miles above the Moon, NASA’s Lunar Reconnaissance Orbiter captures this image of Saturn.


Saturn as seen from 56 miles above the Moon by NASA’s Lunar Reconnaissance Orbiter.

On October 13, 2021, the camera aboard the Lunar Reconnaissance Orbiter (LRO) spacecraft imaged “Lake of Spring” from a viewpoint about 90 kilometers (56 miles) above Lacus Veris.

The Lunar Reconnaissance Orbiter Camera (LROC) was looking down at the north face of the rings in this image, and the rings in front of Saturn appear to be below its equator from this vantage point.

The LROC Narrow Angle Cameras (NAC) are line scan cameras, which make imaging anything other than the Moon difficult.

This is because they were built to acquire images by building up an image one line at a time, with very short exposure times, by taking advantage of the spacecraft’s motion above the surface (LRO travels over 1,600 meters per second (1 mile per second) above the Moon.

To image Saturn, the spacecraft slews the NAC across the planet, emulating our orbital ground motion to build up the image.

By pointing the NACs on one side of Saturn and then targeting the other, the slew across Saturn was accomplished.

LRO slews to the updated target at a set rate across the planet in response to it being updated.

This rate was set to optimize LRO stability and speed, resulting in a 3.82 millisecond NAC exposure time.

We cannot detect the Saturnian moons as we did the Galilean moons because Saturn is much dimmer than the Moon (and) the exposure time is in effect set by the slew speed.

Fortunately, the NACs can image Saturn’s incredible rings, which are only 10 to 100 million years old, 10 meters thick, and almost entirely made of water ice.

The major rings visible here have a diameter of 270,000 kilometers (168,000 miles), which is roughly 70% of the average distance between the Earth and the Moon.

To give you a sense of scale, the image above was taken by the during its grand tour of the solar system.

The Science Mission Directorate at NASA Headquarters in Washington manages LRO, which is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

LRO, which was launched on June 18, 2009, has gathered a wealth of data with its seven powerful instruments, contributing significantly to our understanding of the Moon.

NASA and commercial and international partners are returning to the Moon to expand human presence in space and bring back new knowledge and opportunities.


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