SPACEFLIGHT

above freezing, except at the equator. It sublimes directly into the atmosphere, forming wispy clouds.

Today, water ice is present underground in regions above 30° latitude. Examining Viking photos of impact craters, there is evidence of "terrain softening" which could have been caused by underlying water.

Liquid water may therefore exist about 1km below the surface, heated by high temperatures in the crust.

Shuttle military payload revealed VANDENBERG The first military Space Shut­tle flight from Vandenberg AFB, California, due to take place on March 20 next year with Orbiter Discovery, has been declassified.

The major payload is, as expected, Teal Ruby (P888), an infrared surveillance craft for detecting aircraft in flight. Also being carried, on pallets in the payload bay, are six experiments, including Cirris, a cryogenic infrared radiance instrument. This could not be operated during the fourth Shuttle flight in June 1982, because a lens cap failed to come off.

The five other experiments comprise ultraviolet and X-ray cameras, a gamma ray detector, a horizon ultraviolet photometer, and a quadruple ion neutral mass spec­trometer.

Discovery's polar orbiting mission will be commanded by Bob Crippen, on his fifth Shuttle flight. His crew will be pilot Guy Gardner, mission specialists Dale Gardner (not related), Jerry Ross and Mike Mullane, with payload specialists John Watterson

, and Air Force undersecretary Pete Aldridge.

The flight may be delayed beyond March 20 because a new type of solid rocket booster casing, to be used for the first time on mission 62A, ruptured during a recent structural load test at Nasa's Marshal Space Flight Centre.

-FLIGHT INTERNATIONAL, 2 November 1985

SEP explains VI5 failure VILLAROCHE The cause of the failure of Ariane V15 and its GTE Spacenet 3 and ECS 3 satellites in September has been located and is being remedied, according to engine builder Societe Europeenne de Propulsion (SEP). The next Ariane launch, with Spot 1 and Viking atop, is now set for early January, reports Gilbert Sedbon.

"We now know very well what caused the failure of Ariane V15," says SEP presi­dent Roger Lesgards. "Our inquiry has made ten recom­mendations, all of which we are implementing."

A delay of just 0-4sec in ignition of the third stage engine caused the loss of V15. The third stage is a cryogenic device burning liquid hydro­gen and liquid oxygen

supplied from separate tanks. The propellants are pumped to the combustion chamber, where they are mixed and ignited 8-4sec after burnout of the second stage.

"The liquid hydrogen, which is very light, went through its feed valve too early," Lesgards says. This valve is a sophisticated component which experiences differential temperatures of 250°C in a very short time. For several seconds, there was a leakage, and that was the cause of the failure. "The temperature in the engine became too cold and ignition did not occur because the oxygen and hydrogen did not mix in normal proportions and at the right moment. There was an explosion, and the engine did not start. We are changing the valve and making a few modifications, but we will not have to go through new certification again."

Space Suited

Delaware-based company ILC is designing new suits for extra vehicular activity around the US Space Station as part of a $2-5 million Nasa contract. Manned man­oeuvring unit range will be increased to 100m, and suiting up time will be shortened to avoid lengthy depressurisation times. Flexibility and communica­tions systems will also be improved.

Nasa favours dual-keel Space Station HOUSTON Nasa has reconfigured the US Space Station into a new, box­like structure in a change from the original, tall and long "power tower" approach. The new design will provide a better microgravity platform for materials processing, and a more convenient structure space on which to mount experiments, modules, upper stages and test vehicles.

The structure is called a dual-keel station and involves the use of a rectangular mast 100m long and 50m wide, with a 150m long crossbeam across its centre. Two pairs of solar panels are mounted on the 50m spans of the crossbeam, either side of the rectangle. Additional beams form exten­sions from either side of the top and bottom spans of the rectangular structure.

Voyager 2 meets Uranus PASADENA On November 4, the formal exploration of the planet Uranus by the US spacecraft Voyager 2 will begin. High­light of the mission will be a 107,000km fly-by of the planet on January 24 next year, and encounters with the moons Miranda, Umbriel, Ariel, Titania, and Oberon.

The exploration ends on February 25 when the remark­able spacecraft, launched in 1977, will use the planet's gravity to change its flight path and its orbital motion to increase speed, sending it in an arc towards Neptune, which it will encounter on August 24, 1989.

SPACESHOTS ELA 2, the second Ariane launch pad at Kourou, has been completed and will be used for the first time for the 1986 launch of an Ariane 3, carrying Brazilsat 2 and G Star 2. ELA 2 will enable consecutive launches to be made at approximately monthly intervals, allowing a ten per year launch rate.

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