Previous observations indicated that there was water on the moon. New telescope observations concluded that these results contained water.

The spacecraft saw evidence of water ice in permanently shaded pits at the moon’s poles (SN: 5/9/16), As well as hints of water molecules on the sunlit surface (SN: 9/23/09). But watching water in sunlit areas relied on detecting infrared light with a wavelength that could also be emitted from other hydroxyls, which contain hydrogen and oxygen.

Now, the Stratosphere Observatory for Infrared Astronomy, or Sophia, Discover the unique infrared signal of water near the moon’s south pole, Researchers report online October 26 at Natural Astronomy. “This is the first unambiguous discovery of molecular water on a sunlit moon,” says study co-author Casey Honeyball, a lunar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. This shows that water isn’t just in permanently shaded areas. That there are other places on the moon that we can possibly find. “

These observations could benefit future missions to the moon that will discover lunar waters as a potential source for human visitors (SN: 12/16/19).

SOFIA, operated by NASA and the German Space Center, is a 2.5-meter telescope that is mounted on a jumbo plane for clear views of the sky (SN: 2/17/16). During a flight in August 2018, the telescope detected a 6-μm infrared light emitted from an area near the moon’s southern crater, Clavius. This wavelength of light is generated from the vibrations of water molecules heated by sunlight, but not other compounds containing the hydroxyls, which consist of an oxygen atom attached to a hydrogen atom.

“I thought it was really cool,” says Jessica Sunshine, a planetary scientist at the University of Maryland in College Park, to confirm the presence of water on the moon through observations of this wavelength. Sunshine has participated in previous observations that spotted hints of water on the moon, but was not involved in the new study.

Based on the brightness of the observed infrared light, the Honeypal team calculated the water concentration from about 100 to 400 parts per million around the Clavius ​​crater. That’s less than a pint of water per metric ton of lunar soil. This focus was about what the researchers expected, based on observations of previous spacecraft.

These water molecules are not frozen into ice, like water in the moon’s permanent shadow regions. Sunshine also says it is not liquid. “There are no moon pools.” Instead, water molecules are thought to be bound to some other material on the moon’s surface.

“The only way for us to see the water is on [sunlit] “The moon is if it’s protected from this harsh environment,” says Honeypal. These water molecules can be coated in glass formed by the effects of micrometeorites, or get stuck between grains of soil that shield the water from the scorching rays of the sun.

Water could have formed on the moon itself, from hydrogen ions in the continuous outward flow of charged particles from the sun that interact with the oxygen on the surface (SN: 10/6/14). Or, if the water was stored in a collision glass, it could be delivered to the moon by tiny meteorites.