New year in space; NASA zeros in on planet earth - National Aeronautics and Space Administration 1994 mission schedule

Science News, Jan 15, 1994 by Ron Cowen

At that distance, the gravitational tug of Earth balances exactly that of the sun, and the craft will experience no net gravitational force. Careful navigation and an onboard propulsion system will then keep the craft in its prescribed orbit about the sun, in front of our planet.

This will enable Wind to record the impact of the solar wind one to two hours before the ion stream strikes our planet's magnetosphere, the region in which Earth's magnetic field exerts a strong influence. In combination with other instruments that directly measure Earth's magnetosphere, the craft's detectors should show how Earth responds to different intensities of solar wind.

May: NASA plans to launch another weather satellite for the National Oceanic and Atmospheric Administration (NOAA). Known as the Polar Orbiting Environmental Satellite, now called NOAA-J, the craft will track hurricanes and other weather phenomena from an orbit that circles the poles of Earth. Because it flies at lower altitudes than weather satellites in geostationary orbits (such as GOES-I), which monitor weather at a single spot on Earth, this craft can record more accurate temperatures at a variety of depths and locations in the atmosphere.

Also in May, NASA will launch another in its continuing series of probes to measure global ozone concentrations. Known as the Total Ozone Mapping Spectrometer (TOMS), this instrument is the third generation to fly in space. The last TOMS flew on a Russian satellite in 1991.

The instrument monitors ozone at six wavelengths ranging from 3,100 to 3,800 angstroms. In addition to monitoring ozone, the new TOMS will also measure the amount of sulfur dioxide released by volcanic eruptions.

Two years ago, the Ulysses spacecraft -- a joint venture of NASA and the European Space Agency - swung close to Jupiter, using the planet's gravity as a slingshot to hurl the craft out of the plane in which the planets orbit the sun (SN: 2/22/92, p. 118).

In May, Ulysses embarks on an exploration of the sun's polar regions by passing over the solar south pole -- a feat accomplished by no other spacecraft. Ulysses will reach 70 degrees south solar latitude in May and spend about four months even farther south at a distance of about 330 million kilometers from the sun - about twice the Earth-sun span.

Nine onboard instruments will collect information about the sun's outer atmosphere, or corona; the solar wind; the sun's magnetic field; and cosmic radiation from outside the solar system, (In February 1995, Ulysses will cross the sun's equator and in May of that year begin a similar four-month exploration of the sun's northern polar region.)

June: Complementing the April launch of Wind, NASA this month sends aloft the Polar satellite, which will carry 11 instruments to monitor the flow of the solar wind within Earth's magnetosphere. The craft will track the movement of charged particles from the sun over Earth's magnetic poles. By photographing the northern aurora, the satellite will also observe the energy exchange between the ionosphere, the region just above Earth's upper atmosphere, and the magnetosphere.