Page 31 - Intro to Space Sciences Spacecraft Applications

Introduction to Space Sciences and Spacecraft Applications
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both Venus and the earth for gravity assist boosts to reach the planet
Jupiter and release a probe into its atmosphere. Along the way, Gulileo
flew by the asteroids Gaspra (October 1991) and Ida (August 1993), giv-
ing us our first close looks at these solar system companions.

The Soviets sent numerous spacecraft to explore Venus, and two of their
Venera craft successfully landed on the surface in March 1982. The landers
were only able to transmit pictures and data for a short time until the harsh
environment (temperatures which will melt lead and pressures about 100
times that on earth) disabled the spacecraft. While the United States con-
ducted the first flyby of a comet (Giaccobini-Zinner) in 1985, a flotilla of
spacecraft from the Soviet Union, the European Space Agency, and Japan
made somewhat more noteworthy flybys of Halley’s comet in 1987.

Space Exploration. An Orbiting Astronomical Observatory (OAO 2) was
launched in December 1968 with a complement of ultraviolet instruments
designed to examine the stars, and discovered evidence of the existence of
“black holes.” High-Energy Astronomy Observatory (HEAO) spacecraft
were launched between 1977 and 1979 to conduct X-ray, gamma ray, and
cosmic ray surveys of the universe, and the International Ultraviolet
Explorer (IUE) conducted observations in the UV wavelengths. Launched
in November 1989, the Cosmic Background Explorer (COBE) carried
instruments designed to search the infrared background of deep space for
information about the “Big Bang” theory of the origin of our universe.
Deployed in April 1990 from the Space Shuttle, the Hubble Space Tele-
scope (HST) was the first of the “great observatories,” facility-class satel-
lites designed to offer scientists unparalleled opportunities to explore the
universe. HST has a 2.4-meter (94.5-inch) diameter mirror which can pick
up objects 50 times fainter and 7 times more distant than present ground-
based observatories, potentially expanding the universe visible to
astronomers by five hundredfold! Designed for on-orbit servicing, in
December 1993 astronauts were able to insert a set of corrective optics to
offset the “spherical aberration” flaw discovered in the primary mirror
that compromised HST’s capabilities. The second great observatory, the
Compton Gamma Ray Observatory (GRO), was deployed from the Space
Shuttle in April 1992. GRO was designed to capture the relatively unim-
peded gamma ray emissions from cataclysmic cosmic events like super-
novas, black holes, and even the remnants of the Big Bang. Other great
observatory satellites may follow.