Page 290 - NS-2 Textbook

ASTRONOMY 285

Science
Plasma
!OW..fJain antenna

Extendable
magnetometer
boom \

,,- 4

spectr:ometer
and radiometer

Scieh'ce instfllment
caiibration panel
and,'shunt radiator
PlanetarY,radio
astronomy and
plasma \rvave
antenna

The Voyager spacecraft, showing the various instruments deployed.

Sky/ab, mentioned earliel; contained a group of eight follow-on Voyager spacecraft launched in 1977, all re-
solar obsen'ation instruments and cameras. During the nuned telemetry data (instrunlentation readings) from
time it was manned, between May 1973 and February the outer regions of our solar system. More will be said
1974, about 150,000 observations of the Sun were made. about their discoveries in chapter 4 of this unit.
These produced many spectacular photos of solar flares Mariner reconnaissance spacecraft conducted orbital
and sunspots. The Skylab and OSO data "rewrote the surveys of Mars in the late 1960s and of Venus in the
book" on solar physics, our ,mderstanding of how and early 1970s. Two Viking landers made soft landings on
why the Sun functions, and the effects the Silll has on ter- the Martian surface in the mid-1970s. They sent back
restrial weather and communications. hundreds of pictlU'es of the Martian terrain and con-
While these spacecraft were investigating the nature of ducted experinlents to try to determine whether micro-
near-Earth space, a selies of eleven Pioneer spacecraft be- biallife-forms exist in the soil. Several Soviet probes fit-
gan a reconnaissance of the remainder of the solar system. ted with parachutes penetrated the atulOsphere of Venus
The last of these, Piolleer 10 and Piolleer 11, lmmched in 1972 in the 1970s and 1980s and radioed back some pictures of
and 1973, were the first spacecraft to fly by and photograph the surface and data on temperatures and pressures until
Jupiter and Saturn. For many years afterward, they were the they overheated and shut down. A pair of Soviet recon-
most distant artificial objects from Earth, until they were naissance probes conducted a close flyby of Halley's
overtaken in 1998 by a later but faster Voyager spacecraft. comet during its 1986 swing through the solar system,
Piolleer 10 crossed the orbit of Pluto, the outermost confirming among other observations that the head of
known planet, in 1986, becoming the first artificial object the comet is composed primarily of dirty ice.
to escape the solar system. It is now about 7.6 billion In 1989 the Magellall spacecraft fitted with an ad-
miles from Earth. Its last, weak transmission was re- vanced radar inlaging device was launched to produce a
ceived in 2003; nothing further has been received since. detailed map of the surface of Venus. It arrived in orbit
PioHeer 11, which followed a different path in order to fly over the planet in 1991 and began its task, which ended
by Saturn in 1979, passed Pluto in 1994. They, and two in 1994 with an intentional plll'llge into the Venusian