Soyuz poised to lift off with European weather satellite
BY STEPHEN CLARK
Posted: September 16, 2012
Europe's next polar-orbiting weather satellite will ride a Soyuz rocket into orbit from Kazakhstan on Monday, joining a fleet of international observers dedicated to improving global weather forecasts.
The kerosene-fueled launcher will pitch north from the Baikonur, following a rare trajectory to reach polar orbit from the barren space base.
A rile between the governments of Russia and Kazakhstan delayed the launch from May after a disagreement over drop zones for the Soyuz rocket's four strap-on boosters, which will fall on Kazakh territory north of Baikonur.
First stages from other Soyuz launchers also drop downrange on Kazakhstan, but in a different location east of Baikonur. Russian polar launches usually lift off from the Plesetsk Cosmodrome in far northern Russia.
Authorities announced in June the launch ban had been lifted and MetOp B's Soyuz rocket would blast off in September.
The Soyuz launcher will deploy MetOp B and a Fregat upper stage less than nine minutes into the flight. Two burns of the Fregat engine will place MetOp B in a circular orbit more than 500 miles above Earth.
Release of the 9,005-pound spacecraft is programmed for 68 minutes after liftoff.
Starsem, an affiliate of Arianespace, is managing the launch. The Soyuz 2-1a version of Russia's venerable rocket features a digital control system allowing the vehicle fly a larger payload fairing for commercial flights.
MetOp B is the second of three polar-orbiting observatories owned by Eumetsat - the European Organization for the Exploitation of Meteorological Satellites.
It will replace MetOp A, an identical satellite launched in October 2006 which has surpassed its five-year design life.
Astrium Satellites of France is prime contractor for the MetOp satellites.
Polar-orbiting satellites generate data for numerical models predicting medium-range weather patterns. Weather satellites in geostationary orbit beam back nearly real-time imagery to track clouds, storms and cyclones on shorter timescales.
"The first MetOp spacecraft was launched in 2006 and has now exceeded its design lifetime," said Alain Ratier, Eumetsat's director-general. "Of course, the probability of failure increases beyond the lifetime, and we are also lacking fuel to perform certain maneuvers, which are essential for delivering the best from the [MetOp A] spacecraft. We definitely need to launch MetOp B now."
Observations from two types of polar orbits, timed to cross the equator at 9:30 a.m. and 1:30 p.m. local time, are useful in obtaining data to improve weather prediction and the understanding of climate change.
Polar-orbiting meteorological satellites fly in sun-synchronous orbits to ensure weather data are collected under the same solar conditions worldwide each day.
The MetOp fleet covers the mid-morning orbit, while NOAA's satellites fly in the afternoon orbit.
Instruments aboard the MetOp satellites come from ESA, Eumetsat, NOAA and CNES, the French space agency. Each MetOp spacecraft carries eight weather sensors.
NOAA's contributions include MetOp's advanced very high resolution radiometer, or AVHRR, to collect imagery tracking cloud cover, sea surface temperatures, ice, snow and vegetation characteristics.
The U.S. weather agency also supplies infrared and microwave sounders, which calculate temperature, humidity and pressure profiles within the atmosphere.
CNES provided an advanced infrared atmospheric sounding instrument for MetOp. The French payload detects moisture and temperatures, greenhouse gases and ozone, and can map volcanic ash flows.
Other European instruments include a scatterometer radar instrument to measure wind speed and direction over the ocean, a crucial data point for tropical cyclone forecasting.
Under a new agreement with NOAA to use a U.S. data receiving station in Antarctica, MetOp data will be disseminated within 70 minutes, down from the program's initial 110-minute distribution time, according to Marc Cohen, associate director for Eumetsat's low Earth orbit programs.
The MetOp program's three satellites, launch vehicles, ground segment and flight operations are projected to cost 2.7 billion euros, or nearly $3.6 billion, adjusted for inflation to 2011 levels.
MetOp's third polar-orbiting satellite - MetOp C - will be called up for launch in 2017 or 2018 on a Soyuz rocket when MetOp B reaches the end of its lifetime, Cohen said.
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