July 27, 2021

China launches two small satellites for gravitational wave research


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A Long March 11 rocket lifts off from the Xichang space base with the GECAM mission. Credit: CAS

Two small Chinese satellites designed to detect gamma-ray bursts associated with gravitational waves launched Wednesday on a Long March 11 rocket, beginning an astrophysics research mission to study black holes and neutron stars.

The Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor, or GECAM, mission was developed by the Chinese Academy of Sciences on a rapid timeline of a little more than two years.

The two GECAM satellites, each about 330 pounds (150 kilograms), lifted off on top of a Long March 11 rocket from the Xichang launch base, a site surrounded by mountains in Sichuan province in southwestern China.

The 68-foot-tall (21-meter) solid-fueled Long March 11 launcher fired out of a launch tube on a mobile transporter at 3:14 p.m. EST (2014 GMT) Wednesday. The launch occurred at 4:14 a.m. Beijing time Thursday, according to the China Aerospace Science and Technology Corp., or CASC, the prime contractor for China’s space program.

After heading east from the Xichang launch facility, the four-stage Long March 11 rocket delivered the two GECAM satellites to an orbit about 372 miles (600 kilometers) in altitude, with an inclination of 29 degrees to the equator, according to U.S. military tracking data.

Chinese officials declared the launch a success.

The Chinese Academy of Sciences said the GECAM satellites will operate together as an all-sky monitor to detect gamma-ray bursts associated gravitational waves, ripples in the fabric of spacetime caused by cataclysmic events in the distant universe like collisions between black holes and neutron stars.

The same super-violent events that generate gravitational waves can also produce powerful explosions that send out high-energy gamma rays. The GECAM mission is designed to measure hunt for the gamma ray signals that come with gravitational waves, which were first directly detected by scientists in 2015.

GECAM will also detect high-energy radiation from fast radio bursts, special gamma-ray bursts and magnetar bursts, and other high-energy celestial explosions, according to the Chinese Academy of Sciences.

Scientists will combine GECAM’s observations with gravitational wave detections from ground-based observatories, providing new insights on neutron stars and black holes, the super-dense relics of dead stars left behind after violent supernova explosions.

Chinese scientists said the GECAM mission will also study phenomena closer to come, such as high-energy radiation produced by solar flares and terrestrial gamma-ray flashes over thunderstorms.

Artist’s concept of the GECAM satellites. Credit: CAS

The National Space Science Center of the Chinese Academy of Sciences was responsible for development of the GECAM mission. The Shanghai Institute of Microsatellite Innovation, also part of the Chinese Academy of Sciences, developed the two GECAM satellites.

The academy’s Institute of High Energy Physics set the GECAM mission’s scientific goals and was in charge of development of the spacecraft payloads.

China launched a small satellite named Tianqin 1 last December to test technologies for a future Chinese space-based gravitational wave observatory. The European Space Agency, with assistance from NASA, is also leading developing a space-based mission to detect gravitational waves.

In addition to China’s widely-reported solar system missions — such as the Chang’e moon probes and the Tianwen 1 Mars rover — the Chinese Academy of Sciences said researchers are working on multiple other space science projects.

China is developing the Advanced Space-Based Solar Observatory to study the sun’s magnetic field, solar flares, and coronal mass ejections. A Chinese X-ray astronomy observatory named the Einstein Probe, and a joint Chinese-European mission named SMILE to study the interaction between the solar wind and Earth’s magnetosphere are also in development.

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Follow Stephen Clark on Twitter: @StephenClark1.


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