Eyes in the Sky

U.S. spacemen last week scored two more advances in their stubborn, low-glamour campaign to put space to practical use. For the first time since the race to space began, they achieved two successful satellite firings in a single day. Rising from Cape Canaveral, Fla., a Thor-Delta rocket set a Tiros weather satellite on an almost perfectly circular orbit 463 to 506 miles above the earth and at a 48DEG angle to the equator. Later that same busy day, an Air Force Atlas launched a missile-detecting satellite, Midas III, from Point Arguello, Calif.

Tiros III is an improvement over its predecessor, Tiros II, which was launched Nov. 23 and is still in orbit. The new Tiros carries two identical wide-angle TV cameras to take pictures of cloud patterns above the earth's surface and a new array of infra-red sensors to measure heat that the earth radiates into space. All the gadgets on Tiros III are working fine: cloud-pattern pictures began coming down by radio as soon as the satellite got into orbit. Launched just at the start of the Caribbean hurricane season, Tiros will use its sharp-eyed cameras to detect infant hurricanes when they are only tentative swirls in the dappled cloud patterns over tropical seas.

Midas III reached its polar (north-south) orbit in a highly sophisticated way. First, the Atlas booster took off from the launching pad. After it burned out, the second-stage Agena rocket separated from it, fired for a short time and shut off. With the Midas payload in its nose, it coasted high above the earth. When over Africa, the rocket motor ignited again, giving the Agena and its payload enough speed to stay indefinitely on a 1,850-mile-high orbit. Satellite fanciers call this maneuver a "kick in the apogee.''

While Tiros III is a civilian satellite whose weather pictures will be made available to all the world, Midas III is military and secret. It carries sensitive infra-red sensors that can pinpoint hot spots, such as rocket takeoffs, on the surface of the earth from hundreds of miles away. The Air Force hopes to put ten Midas satellites on polar orbits that will bring them over the Soviet Union as well as every other part of the earth. Whenever a missile or space vehicle is launched, its heat will be seen by the infra-red eyes of the satellites speeding overhead. Defenders of the target nation will know about the missile 15 minutes before it has climbed high enough to show on their radar screens. Midas' first chance to prove itself will come when a U.S. missile is fired just as the satellite comes within sighting range.

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