Short-lived experiment marks the beginning of radio astronomy from the Moon – Sky & Telescope

After a half-century hiatus, NASA finally returned to the lunar surface with a scientific payload in February. It did so aboard the Odysseus lander, the first of NASA-sponsored privately operated missions.

However, the first mission of the agency's Commercial Lunar Cargo Services program, which was designed to reduce costs and accelerate lunar research, did not go exactly as planned. A navigation system malfunction caused the spacecraft to hit the ground harder than expected. One of the lander's legs broke and the spacecraft tipped over, ending up in a strange 30-degree tilt.

Despite the setback, the scientific experiment the lander conducted, called Radio Wave Observations on the Lunar Surface Photo Electron Sheath (ROLSES), yielded data, and researchers on Earth are milking everything that they can.

“All was not lost,” said instrument co-investigator Jack Burns (University of Colorado, Boulder) during a press conference at the 244th Meeting of the American Astronomical Society in Madison, Wisconsin. Burns confirmed that ROLSES became the first radio astronomy experiment to operate on the Moon, where it served as a precursor to future more advanced lunar radio telescopes. The team even managed to collect some unplanned scientific measurements during the trip to the Moon.

The experiment featured an array of four wire antennas and a radio spectrometer, weighing a total of just 4 kilograms (9 pounds). The team designed it with the purpose of investigating how the Moon's porous surface scatters cosmic radio waves. ROLSES landed in the Malapert A crater, near the south pole of the near side of the moon.

The ROLSES team had two opportunities to collect data. The first occurred when an unexpected failure caused one of the 2.5-meter (8-foot) antennas to deploy mid-flight, when the spacecraft was still 10,000 km (6,000 miles) away from the Moon. In images taken by the cameras on board Odysseus you can see the antenna protruding into space.

“We took advantage of that, turned on our radio spectrometer and got some data,” Burns said. With about an hour and a half of data, the researchers clearly detected radio emissions from the Earth, which come from human activity. “We got a nice (frequency) selfie of Earth taken from a unique perspective,” Burns added.

The failure allowed ROLSES to record radio emissions from Earth at a distance, an unexpected repetition of an experiment that Carl Sagan invented in 1993. Sagan used the Galileo spacecraft on its way to Jupiter to obtain a similar observation of Earth; However, the ROLSES data is more comprehensive than what Galileo was able to collect at the time, with better temporal resolution and higher frequencies.

Studying Earth in this way provides a benchmark for detection of exoplanet signals by future lunar telescopes. Our planet's reference point could even allow the identification of possible technosignatures, the signals that extraterrestrial civilizations could produce.

ROLSES' second opportunity to collect data came after the moon landing. The original experiment required eight days of data collection, but the angle of the spacecraft considerably shortened that time to just 20 minutes. However, the device was able to deploy its antennas, collect some data, and return it to Earth.

Despite the setbacks, Burns remains optimistic: the instrument has a second chance. NASA has already given the green light to an improved ROLSES-2 experiment that will fly on another commercial lander in 2026.