On July 25 at 3:13 AM (UTC), a Chinese Long March 4B rocket launched three satellites from LC-9 at Taiyuan Satellite Launch Center.
The biggest payload — weighing in at 2650 kilograms (1325 two-liter soda bottles) — was the Ziyuan-3 03 satellite, which will join the other two Ziyuan satellites in orbit. This is China’s first constellation of high-resolution mapping satellites for civilian use. Until the Ziyuan satellites were launched, China was using other countries’ satellites to collect data for mapping and surveying. The Chinese enthusiast blog SpaceFlightFans reports that this constellation has saved the country hundreds of millions of dollars. A fourth satellite to complete the constellation is planned to launch later this year.
The co-passengers for this flight were Tianqi 10 and Lobster Eye X-ray Exploration Satellite.
Tianqi 10 is the seventh addition to the Tianqi constellation, which provides “much-needed data collection and transmission services for terrestrial network coverage blind areas,” according to Gunter’s Space Page.
Lobster Eye 1 is a joint project between Nanjing University, the University of Hong Kong, and China Aerospace Science and Technology Corporation (CAST). The name refers to an optical principle described in the scientific literature back in 1979 where an instrument constructed similarly to that of a lobster’s eye could observe a large field of view with a minimum of components, an ideal combination for space-based astronomy (large field of view, low weight, and complexity).
Lobster Eye 1 is designed to observe large areas of the sky simultaneously in the soft X-ray part of the electromagnetic spectrum, unlike NASA’s Chandra Observatory that observes in the “hard” X-ray portion of the spectrum. “Soft” X-rays are higher in energy than ultraviolet, but much less energetic than the “hard” X-rays used for things like chest X-rays or bone scans. Earth’s atmosphere blocks soft X-rays, so it’s not possible to observe them from the ground. Some of the science to be done using the Lobster Eye includes X-ray detection and location as well as possible dark matter verification.
BONUS FACT: Soft X-rays are routinely used for medical imaging of fine structures and were the means by which DNA was discovered.
The optics also allow for a wide range of wavelengths to be observed and does so in a way that detects and measures changes in the image over short periods of time, neither of which are practical or possible for hard X-ray detectors like NASA’s Chandra X-ray Observatory.
Twelve minutes after launch, what appears to be the first stage of the rocket crashed down in the mountainside in Yunyang district of Shiyan city, Hubei.
According to Shiyan Evening News, “the landing of the wreckage caused no casualties or economic losses. The local armed forces and public security departments protected the site, and the relevant departments have processed the wreckage.”
Xinhua News Agency article (Chinese)
Tianqi 10 (Gunter’s Space Page)