A Soyuz ST-A took to the early evening skies Monday, April 25. It was tasked with orbiting a cluster of European satellites designed for Earth observation, astrophysical research, and educational purposes. The booster lifted off at 6:02 p.m. GFT (5:02 p.m. EDT / 21:02 GMT) from Guiana Space Centre’s Soyuz Launch Complex (ELS) located in Sinnamary, French Guiana.
The launch was carried out by European launch service provider Arianespace. The mission was designated VS14 in the company’s numbering system and was the first Soyuz launch performed by the company this year (2016). It also came later than planned.
The launch had been scheduled to take place three days earlier, on Friday. However, weather conditions in the area were deteriorating and mission managers opted to push the launch back—first to Saturday and then to Sunday due to unfavorable upper-level winds over the South American spaceport. The launch time during each launch attempt was fixed at the same point each evening.
In the final hour of the Sunday countdown, a technical anomaly—a rare occurrence for the venerable booster—caused yet another delay. It was in the Inertial Measurement Unit (IMU).
“Faulty IMU will be replaced,” Arianespace Chairman and CEO Stephane Israel tweeted. “Launch targeted for [Monday].”
The IMU is located on the third stage of the booster and is used to determine the Soyuz’s heading and orientation during ascent. The information is fed into the guidance computers, which gives steering commands to the engines.
Preparations for the launch have been underway since March 1 when initial tests of the rocket’s Fregat upper stage commenced. Later that month, the Sentinel 1B spacecraft and payload was delivered to the launch site in French Guiana. The Soyuz ST-A launch vehicle was rolled out to the pad Tuesday, April 19.
Liftoff started with the core stage and its four liquid-fueled boosters sending the stack on a short vertical ascent. Nearly two minutes into the flight, the boosters were jettisoned, leaving the launch vehicle dependent on the core stage’s engine. The payload fairing separated approximately three minutes and 29 seconds into the flight.
The core stage continued to accelerate the booster downrange until it was detached from the rocket about four minutes and 48 seconds after liftoff. Then the third stage took control of the flight for about four minutes.
After it finished firing and separated, the Fregat upper stage conducted its first burn nearly ten minutes after launch and started guiding the payload toward the designated orbit.
The Sentinel-1B satellite, the mission’s main passenger, was deployed at 23 minutes and 35 seconds into the flight. It will be placed into a low-Earth orbit (LEO) at an altitude of 426 miles (686 kilometers), with an inclination of 98.18 degrees.
Weighing nearly 2.4 tons (2.2 metric tons), the Sentinel-1B spacecraft measures about 11 feet (3.4 meters) in height and has a diameter of 7.6 feet (2.3 meters). Manufactured by Thales Alenia Space, the spacecraft is based on the PRIMA bus. It is capable of generating up to 6,000 watts of power with its deployable solar arrays and is designed to be operational for up to seven years.
Sentinel-1B is a synthetic aperture radar (SAR) type C-band observation satellite. It will join its identical twin, Sentinel-1A, which was launched two years ago. These two satellites will work together to image any point on Earth in less than six days. Their powerful radar sensors will provide real-time all-weather coverage of land surfaces and bodies of water in Europe and the polar regions.
Sentinel satellites are part of a research program called Copernicus, managed jointly by the European Space Agency (ESA) and the European Union. The program aims to provide operational information on land masses, oceans, and Earth’s atmosphere. The system consists of Earth observation satellites and in-situ sensors such as ground stations, airborne and seaborne sensors.
|Sentinel-1. Credit: ESA/ATG medialab|
After deployment of Sentinel-1B, the Fregat carried on with its mission. It will burn for a second time about two hours into the flight. Forty-eight minutes later, it will deploy a trio of CubeSats called “Fly Your Satellite!”
“Fly Your Satellite!”consists of three student-built 4-inch (10-centimeter) CubeSats: OUFTI-1, e-st@r-II, and AAUSAT-4.
Built by the University of Liege in Belgium, OUFTI-1 will test a new communications subsystem. E-st@r-II, from the Polytechnic of Turin, Italy, will demonstrate an attitude determination system using measurements of the Earth’s magnetic field. AAUSAT-4, provided by the University of Aalborg, Denmark, will operate an Automated Identification System (AIS) receiver in order to identify and track the position of ships transiting away from coastal areas.
The project is part of the newly-established ESA Education and Knowledge Management Office’s program. The aim of this program is to give university students across Europe the chance to gain practical experience in key phases of developing a real satellite project—from integration, testing, and verification all the way to launch and operations. The CubeSats will be put into an orbit with a perigee of some 281 miles (453 kilometers) and an apogee of 413 miles (665 kilometers).
The Fregat upper stage will conduct a third burn three hours and 32 minutes after liftoff. A fourth burn will be performed about 25 minutes later before the satellite is deployed. The Microscope satellite will separate from the upper stage approximately four hours into the flight.
The Microscope is a box-shaped microsatellite with a mass of about 668 pounds (303 kilograms). Its dimensions are 4.6 feet by 3.3 feet by 4.9 feet (1.4 meters by 1 meter by 1.5 meters). The spacecraft, based on the Myriade bus, features two solar cells and is designed to be operational for up to three years. It was developed by the French space agency CNES.
The Microscope satellite will test the equivalence principle described by Albert Einstein by using two concentric cylindrical test masses made of different materials—one titanium and one a platinum-rhodium alloy. It will be conducting its research at an altitude of 442 miles (711 kilometers), inclined 98.23 degrees.
The 151-foot (46-meter) tall Soyuz ST-A rocket that was employed in Sunday’s launch is based on the Russian Soyuz-2 developed by TsSKB-Progress. It is a four-stage launch vehicle: four boosters (first stage) powered by four RD-107A engines, a central core (second stage) fitted with an RD-108A engine, a third stage using an RD-0110 engine, and the restartable Fregat upper stage (fourth stage) powered by a single S5.92 engine.
The booster also includes a payload adapter/dispenser and fairing. The rocket is capable of delivering up to 3 tons (2.7 metric tons) into a geostationary transfer orbit (GTO), and about 5 tons (4.5 metric tons) into a Sun-synchronous orbit (SSO). The ST-A version was flown for the first time in December of 2011.
VS14 is the third Arianespace mission in 2016 and the sixth Soyuz flight this year. Sentinel-1B is the 51st ESA satellite launched by Arianespace. The company’s next mission is scheduled for May 24, 2016, when a Soyuz ST-B launcher will send two ESA Galileo satellites into orbit.