augural flight was made by the space shut-
tleColumbiaon April 12, 1981. However,
the disastrous explosion ofChallengerwhile
launching on January 28, 1986, grounded
the four-shuttle fleet for two years and
resulted in even more emphasis being
placed upon the use of uncrewed vehi-
cles.
Satellite Observatories NASA put into
Earth orbit four U.S.-produced astronomi-
cal observatories, two of which studied
the Sun and two of which surveyed distant
phenomena in the universe. Solar Maxi-
mum Mission was launched on February
14, 1980, and, after repair by a space shut-
tle crew in 1984, collected data on solar
flares until 1989. Orbited on October 6,
1981, Solar Mesosphere Explorer moni-
tored fluctuations in the Sun’s produc-
tion of ultraviolet light for five years. The
Infrared Astronomical Satellite (IRAS),
the first of its kind, reached orbit on Janu-
ary 26, 1983, in a joint project with the
United Kingdom and the Netherlands.
During its ten months of operations, IRAS
examined more than 96 percent of the
heavens, cataloging thousands of previ-
ously unknown galaxies and star-birthing
gas clouds. It also discovered five new comets in
the solar system. The Cosmic Background Explorer
(COBE) entered orbit on November 18, 1989, and
for four years mapped infrared background radia-
tion to learn about the origin of the universe.
Landers and Deep Space Probes The decade
opened with six of NASA’s most renowned missions
under way. Two landers were on Mars, taking photo-
graphs of the surface and gathering data on Martian
soil and atmospheric conditions. Both had been
launched in 1975; Viking 1 was operational until No-
vember 13, 1982, and Viking 2, until April 12, 1980.
In addition, four probes were speeding deep into
the solar system. Pioneer 10, launched in 1972, and
Pioneer 11, launched in 1973, were far past their
chief planetary objectives but continued transmit-
ting to Earth valuable data about interplanetary
magnetic fields, dust, and cosmic rays.
The most productive and far-ranging probes, how-
ever, were Voyager 1 and Voyager 2, both launched
in 1977 on a “Grand Tour” of the solar system’s larg-
est planets. From November 12 until December 15,
1980, Voyager 1 photographed the moons, rings,
and atmosphere of Saturn and took magnetic and
temperature readings. It revealed greater complex-
ity in the rings than had previously been realized,
found three new moonlets, and detected a thick, hy-
drocarbon-rich atmosphere on the moon Titan, a
possible venue for life. Voyager 2 began collecting
data on Saturn on June 5, 1981, and by the time it
flew beyond instrument range three months later,
it had taken high-resolution photographs of four
moons and further studied Saturn’s ring system.
Voyager 2 went on to Uranus, becoming the first
craft to visit that planet. The flyby there, lasting from
November 4, 1985, to February 25, 1986, produced
photographs of the planet’s thick clouds, showed
that it rotated at 98 degrees from its orbital plane, ex-
amined its nine rings, and discovered ten new, small
moons. The probe’s next encounter (and another
first) was with Neptune, making its closest approachThe Eighties in America Space exploration 895
The Voyager spacecraft undergoes vibration testing.(NASA-JPL)