On December 9th at 20:14 UTC, a Long March 11 rocket took off from LC-4 at Xichang Satellite Launch Center in southwestern China.

Onboard were a pair of Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor (GECAM) satellites. The satellites will situate themselves on opposite sides of the Earth and will work together like a pair of eyes to watch the entire sky. They’re looking for fluctuations in the gamma-ray bit of the electromagnetic spectrum and for charged particles. 

Not a lot of objects give off light at these high energy wavelengths, and even fewer give off both light and particles. One of the few events to fit the bill is a kilonova – a flash of light and particles that occurs when two neutron stars merge. These events were identified for the first time thanks to their gravitational waves back in 2017. That initial discovery inspired the rapid-fire construction and launch of these twin spacecraft.

It usually takes years to design and construct a science mission, so this is remarkable. Since it’s not practical to identify the location of gamma rays or cosmic rays with a single detector, the twin spacecraft make things a bit easier. By looking at the difference in time between when each spacecraft detects light and particles, they can narrow down where in the sky a new merger has taken place.

This is a super cool new set of science missions, and we’re looking forward to seeing what all they discover.

More Information

Chinese Academy of Sciences press release (Chinese)

China Space article (Chinese)

China Space article (Chinese)

Xinhua Net news 

GECAM info page (Gunter’s Space Page)