The unfolding of one of the three antennas. This series of three photographs was taken during the unfolding of an antenna on the Queqiao satellite, which is located behind the Moon at around 450 thousand kilometers from Earth. The antenna is the black-and-white rod pointed away from the camera. The gilded cube is the casing in which the antenna has waited to be unfolded for 18 months.
Credit: Marc Klein Wolt/Radboud University

The antennas of a radio astronomy experiment have been deployed from China’s Queqiao lunar relay satellite.

The detector is a joint development by Dutch and Chinese scientists, designed to measure radio waves originating from the period directly after the Big Bang, when the first stars and galaxies were formed.

Queqiao, meaning Magpie Bridge, was launched on May 21, 2018. It was then maneuvered into a halo orbit around the second Lagrangian point of the Earth-Moon system.

An earlier image from Queqiao relay satellite shows Netherlands Chinese Low-Frequency Explorer (NCLE) stowed antenna, the Earth, and farside of the Moon. Queqiao is in a halo orbit at L2 Lagrange point.
Courtesy: Radboud Radio Lab

Communication link

From its Earth-Moon position, the satellite provides a communication link between the Earth and the Moon’s farside, and has been instrumental in the continuing operation of China’s Chang’e-4 lander and Yutu-2 rover.

Chang’e-4 soft landed within Von Karman Crater in the South Pole-Aitken Basin on the farside of the Moon on January 3, 2019.

Radio antennas of the Netherlands Chinese Low-Frequency Explorer (NCLE), developed by ASTRON, Radboud Radio Lab, ISIS and the National Astronomical Observatories of China (NAOC).
Credit: Radboud Radio Lab/ASTRON/Albert-Jan Boonstra

Start of science observations

The radio antenna — Netherlands Chinese Low-Frequency Explorer (NCLE) — was developed by Radboud Radio Lab of Radboud University, ASTRON, the Netherlands Institute for Radio Astronomy in Dwingeloo, and the Delft-based company ISIS, along with the Chinese National Astronomical Observatory of the Chinese Academy of Sciences (NAOC).

Tweets Marc Klein Wolt, managing director of the Radboud Radio Lab: “We are so proud, not only of this success which marks the start of our science observations, but also because as of now we are an official radio astronomical observatory in space!”

“Our contribution to the Chinese Chang’e 4 mission has now increased tremendously,” Wolt said in a press statement. “We have the opportunity to perform our observations during the fourteen-day-long night behind the Moon, which is much longer than was originally the idea. The Moon night is ours, now.”

The Netherlands-China Low-Frequency Explorer (NCLE) is onboard China’s Queqiao relay satellite.
Credit: Radboud Radio Lab of the Radboud University, the Netherlands Institute for Radio Astronomy (ASTRON) and Innovative Solutions in Space (ISIS).

Deployment issues

In a Radboud University statement, the longer stay behind the Moon most probably did have an effect on antenna deployment.

“At first, the antennas unfolded smoothly, but as the process progressed, it became increasingly difficult,” the statement explains.

“The team therefore decided to collect data first and perhaps unfold the antennas further at a later point in time. With these shorter antennas, the instrument is sensitive to signals from around 800 million years after the Big Bang. Once unfolded to their full length, they will be able to capture signals from just after the Big Bang.”

According to China’s Xinhua news service, citing scientists involved with the detector, it will be able to observe the radio bursts of Earth, Jupiter and other planets, conduct collaborative observation with the low-frequency radio spectrometer on the Chang’e-4 lander and similar instruments on Earth, and help explore exoplanets.

Go to this video showing one of the NCLE antenna elements deploying during a pre-launch test.

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