China’s first astronomical satellite, an x-ray telescope that will search the sky for black holes, neutron stars, and other extremely energetic phenomena, raced into orbit today after a morning launch from the Gobi Desert.
The 2.5-ton Hard X-ray Modulation Telescope (HXMT), dubbed Insight according to the official Xinhua news agency, was carried aloft by a Long March-4B rocket from the Jiuquan Satellite Launch Center. The newest of several x-ray telescope in space, the HXMT will observe some of the most turbulent processes in the universe. The x-rays generated by those events cannot penetrate Earth’s atmosphere; they can only be observed by instruments mounted on high-altitude balloons or satellites. The HXMT carries three x-ray telescopes observing at energies ranging from 20 to 200 kilo-electron volts as well as an instrument to monitor the space environment, according to its designers. While orbiting 550 kilometers above the planet, the HXMT will perform an all-sky survey that is expected to discover a thousand new x-ray sources. Over an expected operating lifetime of 4 years, it will also conduct focused observations of black holes, neutron stars, and gamma ray bursts.
This latest achievement by China’s space science program “is certainly welcomed” by the astronomical community, says Andrew Fabian, a theoretical astrophysicist at the University of Cambridge in the United Kingdom. “It’s very meaningful that they’ve launched their first astronomical satellite and this will pave the way for others,” he says. Fabian predicts that the HXMT sky survey will prove particularly valuable for catching transient x-ray sources that emerge, flare up to tremendous brightness, and then just as quickly fade away. As yet, the processes behind x-ray transients are poorly understood. Other missions are also trying to catch transients in the act. But “any satellite looking at that phenomena is going to find interesting things and do good science,” Fabian says.
The HMXT is the last of the cluster of four space science missions covered under China’s 12th 5-year plan that were developed by the National Space Science Center (NSSC) of the Chinese Academy of Sciences in Beijing—the other three are a dark matter probe, a collection of microgravity experiments, and a test of long-range quantum entanglement. Funding constraints meant all four had to be developed simultaneously, and all four were launched over the course of 18 months. “This is not a sustainable way to have a science program,” NSSC Director Ji Wu told Science in a 2016 interview.
It would be better to get steady funding annually instead of in 5-year lump sums, he said. Nevertheless, NSSC has again gotten a 5-year budget to develop its next batch of four space science missions, all of which will likely be launched between 2020 and 2022. Among these is the Einstein Probe, a next-generation x-ray telescope that Fabian expects will build on the accomplishments of the HXMT.
By Dennis Normile