Jun 5 1985
From The Space Library
Although a mission to put a human colony on Mars seemed unlikely anytime soon, members of the National Commission on Space [see U.S. Space Policy/National Commission on Space, Mar. 29] said it appeared to be only a matter of time until such an undertaking took place, the Washington Post reported. The commission was due in May 1986 to present a report outlining what it thought the U.S. space program should look like over the next 20 years.
The U.S. last visited Mars in 1976, when unmanned Viking 1 and 2 missions landed and began collecting data. The Mars Observer was scheduled for a 1991 launch to study the planet from orbit. NASA officials said that beyond that there was nothing concrete on the drawing boards, although they were considering sending an unmanned craft to land on Mars, collect samples, and return in a manner similar to early moon explorations. (W Post, June 5/85, A5)
NASA announced that flight controllers for its International Cometary Explorer (ICE) performed the first and largest of four midcourse corrections to direct the spacecraft toward a September 11 intercept of Comet Giacobini Zinner. Conducted from ICE mission control at Goddard Space Flight Center, these corrections used two thousand pulses of the spacecraft's two-lb. hydrazine thrusters to change its heading so it would fly through the comet's tail 16,200 miles from the comet's nucleus. The thruster burns lasted four-and-a half hours.
In 1982, NASA redirected the International Sun-Earth Explorer, which was launched in 1978, toward the comet for what would be the first satellite/ comet encounter in history. This encounter would provide scientists with their first look at the makeup and dynamics of a comet's tail.
The ICE trajectory adjustment would place the satellite/comet encounter within the coverage window of the world's largest single dish radio astronomy telescope located at the Arecibo Observatory, Puerto Rico. The 300-m dish, managed by the National Science Foundation, would supplement coverage by three NASA Deep Space Network stations at Goldstone, California; Madrid, Spain; Canberra, Australia; and the recently completed 64-m antenna of the Japanese Space Agency at Usuda, Japan.
NASA based ICE's course adjustment on telescopic observations of Giacobini-Zinner as the comet emerged in April from behind the sun, the first observation since July 1984. The comet was approximately 149 million miles from the sun on the inbound leg of its orbit between the sun and the neighborhood of Jupiter.
NASA would direct three smaller orbit maneuvers as ICE approached the comet, the last scheduled for three days prior to encounter. Course corrections were necessary because material spontaneously outgassed from the comet's core, acting as jet thrusters on the comet's body, slightly altered the its orbital path.
Astronomers in 1900 discovered Giacobini-Zinner, which returned to earth's neighborhood every six-and-one-half years. It would not be visible to the naked eye, but amateur astronomers with small telescopes would be able to see it. (NASA Release 85-86)
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