Tuesday, November 21, 2017

Long March 6 Launches a Trio of Jilin-1 Earth-Observing Satellites Into Orbit

Long March 6 launches trio of Jilin-1 satellites on November 21. Credit: Xinhua

A Long March 6 rocket took to the skies for the second time in history on Tuesday, November 21, carrying three Jilin-1 satellites designed for Earth observation purposes. Liftoff took place at 4:50 GMT (11:50 p.m. EST on Monday) from the Launch Complex 16 at the Taiyuan Satellite Launch Center (TSLC) in China’s Shanxi Province.

The launch of the mission was initially targeted for July 2017, however due to setbacks with Long March 3B in June and Long March 5 in July, China was forced to halt its orbital flights for three months. The confirmation of the new launch date came in late October, when engineers finished the assembly of the Long March 6 rocket and the satellites were shipped to Taiyuan.

Firing up its one YF-100 engine, the first stage of the Long March 6 booster started powering the launch vehicle during the initial phase of the flight. Chinese media keep the details about the timeline of the mission under wraps, however the flight most likely lasted about 15 minutes until the separation of the satellites.

After separation, the three Jilin-1 satellites, designated Jilin-1 04, 05 and 06, were inserted into a highly-inclined sun-synchronous orbit (SSO) at an altitude of 332 miles (535 kilometers).

Named after China’s Jilin province, Jilin-1 satellites were developed and produced by Chang Guang Satellite Technology Co., Ltd. Each Jilin-1 spacecraft weighs around 209 lbs. (95 kilograms) and has dimensions of 3.6 by 3.9 ft. (1.1 by 1.19 m). The satellites feature a fixed solar array and are designed to offer their services for more than three years.

Jilin-1 are commercial remote sensing satellites designed to provide high definition video imaging. In particular the satellites will deliver imaging, video, multispectral and wide swath coverage of the ground from low-Earth orbit (LEO). The data obtained by these spacecraft will be used for land resources monitoring, land surveying and mapping, mineral resources development, smart city construction, agriculture yield estimation, environmental monitoring, disaster prevention and other areas.

When it comes to Jilin-1 04, 05 and 06, they are expected to deliver video imaging with a swath width of 11.9 by 2.8 miles (19 by 4.5 kilometers) with a resolution greater than 3.3 ft. (one meter).

“Researchers greatly improved the temporal resolution of the new satellites, reducing the visiting time (the length of time it takes for the orbiting satellite to fly by a certain point) from three days to one day, which will greatly upgrade service ability and promote marketing in sensing satellites,” China Daily reports.

So far, China has launched three Jilin-1 satellites into space – Jilin-1 01 and Jilin-1 02 (in October 2015) as well as Jilin-1 03 (January 2017). Chang Guang Satellite Technology intends to have 10 Jilin-1 satellites operational till yearend, therefore next two spacecraft in the series should be delivered into orbit also in November, by a Long March 11 rocket. However, the exact date of the mission is still unknown.

By 2020, the company aims to have a network of 60 spacecraft in service, hoping that it will allow to offer a 10-minute revisit capability of satellites anywhere in the world. By 2030, this network should expand to 137 satellites.

The 95 ft. (29 meters) tall Long March 6 used for Tuesday’s mission is China’s new generation light-lift booster. It is a three-stage small satellite launcher capable of placing up to 2,380 lbs. (1,080 kg) into a SSO. The launch vehicle has a diameter of 11 ft. (3.35 m) and weighs about 103 metric tons. It was developed by the China Academy of Launch Vehicle Technology.

The rocket’s first stage measures around 49 ft. (15 m) in length and 11 ft. (3.35 m) in diameter. It consists of a single YF-100 engine that burns kerosene and LOX (liquid oxygen) propellant, which causes less pollution compared to the UDMH/N2O4 (nitrogen tetroxide) that is currently in use. This stage burns for approximately three minutes.

The 24 ft. (7.3 m) long second stage measures some 7.4 ft. (2.25 m) in diameter. It is powered by a single YF-115 engine that has the ability of performing more than one burn for injections into a variety of orbits.

The third stage measures about 5.9 ft. (1.8 m) in length and 7.4 ft. (2.25 m) in diameter. It is equipped with four YF-85 engines and is capable of making multiple burns over a long mission duration.

Long March 6 is described by the country as being the first carrier rocket that uses fuel free of toxicity and pollution. China hopes it will help the nation to cut the expenses tied to sending payloads aloft.

Maiden flight of Long March 6 took place on September 20, 2015 when it put a fleet of 20 microsatellites into orbit, launching from Taiyuan.

Tuesday’s liftoff was the 255th mission carried out by the Long March vehicle family. It was also the 13th orbital launch for China this year. Next Chinese mission is scheduled for November 25 when a Long March 3B rocket will send two BeiDou-3 navigation satellite into orbit.

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