The Moon itself is an exciting destination, but once the Apollo 16 astronauts landed, they used it as a viewing platform to look deep into the cosmos.
Astronauts Charles M. Duke Jr., the lunar module pilot, and John W. Young, the commander, spent a little under three days on the Moon in April 1972. Thanks to them, for the very first time, a telescope explored the vastness of space from the surface of another planetary body.
The telescope, called the Far Ultraviolet Camera/Spectrograph, looked at distant objects in ultraviolet light, a type of radiation invisible to our eyes. While some ultraviolet rays from the Sun reach the Earth’s surface – which is why we need to wear sunscreen! — our planet’s atmosphere absorbs a lot of the most high-energy rays. Stars and other astronomical objects hotter than the Sun give off a lot of short-wavelength ultraviolet light, but from our planet’s surface we wouldn’t be able to detect it.
The Moon, on the other hand, has no substantial atmosphere to block out such signals, making it a great venue not just for stargazing, but exploring deep into the universe. Young took the telescope out of its plastic bag and planted it on a tripod in the shadow of the lunar module, so that the instrument would get no direct sunlight. The astronauts re-oriented the telescope several times during their stay so that they could see different parts of the sky.
The Moon-based telescope studied a variety of star clusters as well as nebulae – clouds of gas and dust where new stars will be born. Astronauts also pointed it at the Large Magellanic Cloud, which is a small galaxy orbiting the Milky Way. It is called a “Camera/Spectrograph” because it had two modes of operating: “direct images,” which are pictures as from a regular camera, and “spectrograph” which is a way of splitting light to look for the fingerprints of atoms and molecules in astronomical objects.
Notably the telescope also looked back at Earth, viewing its upper atmosphere, called the “geocorona,” and aurorae. The principal investigator, George Carruthers, who had received a patent for such a camera while at the Naval Research Laboratory, said afterward: “The most immediately obvious and spectacular results were really for the Earth observations, because this was the first time that the Earth had been photographed from a distance in ultraviolet light.”
In total, the astronauts returned 178 frames of film from the telescope.
While this camera wasn’t the first space telescope – there were other ultraviolet light-collecting instruments that flew on sounding rockets and in Earth orbit before it – it was the first of a truly interplanetary nature. Later, on the final flight of Skylab, a backup version of the same camera looked at ultraviolet signals from a comet and other objects. Today, NASA’s Hubble Space Telescope delivers stunning images and gains wondrous insights about the universe by also looking at ultraviolet light.
The Far Ultraviolet Camera/Spectrograph remains on the Moon in the Descartes highland region today. It is a reminder that going to the Moon is a step forward not just in our understanding of our solar system, but also what lies beyond.
NASA’s lunar exploration plans are based on a two-phase approach: the first is focused on speed – landing astronauts on the Moon by 2024 – while the second will establish a sustained human presence on the Moon by 2028. The agency will use what we learn on the Moon to prepare for the next giant leap – sending astronauts to Mars.