From Spaceflight Insider: “China launches X-ray space telescope to unravel mysteries of universe”


Spaceflight Insider

June 16th, 2017
Tomasz Nowakowski

A Long March 4B rocket took to the skies on Thursday, June 15, 2017, carrying an important astronomy mission for China. The Hard X-ray Modulation Telescope (HXMT), dubbed “Insight”, will search for black holes, pulsars, and other phenomena with the aim of uncovering the most intriguing secrets of the universe.

Thundering off the launch pad at the Jiuquan Satellite Launch Center in the Gobi Desert, the Long March 4B vehicle lifted off at exactly 11:00 a.m. local time (03:00 GMT; 11:00 p.m. EDT on June 14). Some 25 minutes later, the success of the launch was confirmed by Chinese media as they announced that the spacecraft was inserted into a Sun-synchronous orbit (SSO) of 342 miles (550 kilometers), inclined 43 degrees. This orbit was chosen to avoid radiation from Van Allen belt and the influence of the South Atlantic Geomagnetic Anomaly, which could generate severe disturbances.

The launch of HXMT was originally targeted for 2010; however, it was postponed several times, mainly due to financial issues. The project was proposed in 1993 and, according to initial plans, the Long March 2D rocket was picked as the launch vehicle for this mission. HXMT is a joint effort of the Ministry of Science and Technology of China, the Chinese Academy of Sciences (CAS), and Tsinghua University.

Artist’s rendition of HXMT in space. Image Credit: Xinhua / SASTIND

HXMT is equipped with three different detectors covering a broad energy range from 1 to 250 kiloelectron volts (keV): the high energy (HE) X-ray telescope (20–250 keV), the medium energy (ME) X-ray telescope (5–30 keV), and the low energy (LE) X-ray telescope (1–15 keV). The trio of instruments will enable the spacecraft to conduct the hard X-ray all-sky survey of high resolution and high sensitivity. One extraordinary fact is the HE telescope has a total detection area of more than 5,000 square centimeters – the world’s largest in its energy band.

“Given it has a larger detection area than other X-ray probes, HXMT can identify more features of known sources,” said Xiong Shaolin, a scientist at the Institute of High Energy Physics of the CAS.

Besides performing an all-sky survey, HXMT will carry out deep pointing observations of interesting sky regions and continuous observation of extraordinary sources for spectroscopy and timing study. The spacecraft will also conduct a periodic survey of the Galactic plane.

The HXMT satellite will observe such phenomena like black holes, pulsars, and gamma-ray bursts, among many others. Therefore, the spacecraft is expected to detect a large amount of new transient X-ray sources as well as reveal more insights into temporal and spectral properties of accreting black holes and neutron star systems. This could help researchers to untangle the most puzzling mysteries of the universe.

“We are looking forward to discovering new activities of black holes and studying the state of neutron stars under extreme gravity and density conditions, and physical laws under extreme magnetic fields. These studies are expected to bring new breakthroughs in physics,” said HXMT lead scientist Zhang Shuangnan.

Celestial sources of hard X-rays, in the energy band between 10 and 200 keV, are of special importance to scientists studying high-energy astrophysical processes as they could help answer some of the fundamental questions in astrophysics.

However, there has been no hard X-ray all-sky survey of high sensitivity to date, hence the scientific community hopes that HXMT will change this situation, significantly improving our knowledge in this matter.

“Our telescope may discover new phenomena, or even new celestial bodies. We are looking forward to new findings that nobody can predict. I hope my predictions are wrong since the most interesting astronomical discoveries are all out of expectations,” Shuangnan said.

HXMT was not the only spacecraft launched Long March 4B on Thursday, as three smaller Earth-observing satellites piggybacked on the mission.

Weighing about 81.5 pounds (37 kilograms), the Argentinian ÑuSat-3 is part of the Aleph-1 constellation developed and operated by Satellogic S.A. With dimensions of 15.7 by 16.9 by 29.5 inches (40 by 43 by 75 centimeters), the satellite is equipped with an imaging system operating in visible light and infrared. It will deliver commercial images of Earth, available for the general public.

The two Zhuhai-1 satellites, which will be operated by China-based company Zhuhai Orbita Control Engineering Ltd., have a mass of 110 pounds (50 kilograms) each. They are fitted with a high-resolution video system capable of capturing 20 frames per second and reaching a ground resolution of 6.5 feet (1.98 meters).

The Long March 4B

The three-stage Long March 4B carrier rocket employed for Thursday’s launch is China’s long-serving booster, designed to deliver satellites into low-Earth (LEO) and Sun-synchronous orbits. The 150 feet tall launch vehicle has been in service for over 18 years and has conducted 29 missions, only one of them was unsuccessful.

With a mass of 249 metric tons, the Long March 4B booster is capable of delivering up to 4.2 metric tons to LEO, 2.8 metric tons to SSO, and 1.5 metric tons to a geostationary transfer orbit (GTO). The rocket’s first stage is 91.5 feet (28 meters) long and is 11 feet (3 meters) in diameter. It is powered by four YF-20 engines. The second stage, 35 feet (11 meters) long and 11 feet (3.3 meters) in diameter, is equipped with one YF-22C main engine and four YF-23C vernier engines. The 49 feet (15 meters) long third stage is 9.5 feet (3 meters) in diameter and is powered by two YF-40 engines.

Thursday’s liftoff was the first launch of the Long March 4B booster and the sixth mission for China this year. It was also the third launch from the Jiuquan in 2017.

The next Chinese launch is planned for June 18 when a Long March 3B rocket is scheduled to send the Chinasat-9A communications satellite into orbit. Liftoff will take place from the Xichang Satellite Launch Center, located in China’s Sichuan province.

A Long March 4B rocket carrying the Hard X-ray Modulation Telescope (HXMT) blasts off from Jiuquan Satellite Launch Center on June 15, 2017. Photo Credit: Zhen Zhe / Xinhua

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