The Soviet Union's October 1957 launch of Sputnik, the first satellite, stunned the world. It kicked off the "space race" between the Soviet Union and the United States, and in doing so, changed the course of history. Space would become an important setting in which nations could demonstrate political and scientific prowess. The United States responded to Sputnik in January 1958, launching Explorer I, a simple, inexpensive spacecraft built to answer basic questions about Earth and near space.
Explorer and its immediate descendants were small satellites, but only because of launch-vehicle limitations. Size and complexity of later spacecraft grew to match launch capability. Not surprisingly, the early years of the space race saw U.S. projects expand on many levels. The Cold War spurred the buildup of a massive space-based defense and communications infrastructure in the United States. The government and its contractors, essentially unchecked by budgetary restrictions, developed large, sophisticated, and expensive platforms to meet increasingly demanding mission requirements. NASA followed the lead of DOD, building complex scientific and interplanetary spacecraft to maximize research capabilities.
U.S. expertise in space science was escalating. Launch-vehicle capability continued to grow from the 1960s through the early 1980s, with large satellite platforms carrying more powerful payloads (and, often, multiple payloads). Engineers and scientists worked to perfect the technologies necessary for mission success and lengthier operations. Major research spacecraft took nearly a decade to develop, and they grew to cost more than $1 billion.
As years passed, however, several factors pointed to a need to scale back. With the end of the Cold War, government spending in science and technology received increased public scrutiny. Funding for large, complex flagship missions would no longer be available. Budget constraints forced program managers to look seriously at smaller platforms in an attempt to get payloads onto less-costly launch vehicles.
At the same time, the public voiced a growing concern over the potential for reduced research findings in the wake of several failures of large, high-profile, expensive NASA missions; for example, a crippling manufacturing defect was discovered on the Hubble Space Telescope. NASA came under fire for its perceived inability to deliver quality scientific research.
The scientific community expressed frustration about the lack of flight opportunities because only a few flagship missions, with decade-long development times, were being undertaken. After the limited-capability launch of Galileo in 1989 and the loss of Mars Observer in 1993, the next planetary mission to be launched was the Cassini mission to Saturn in 1997, which wouldn't start transmitting data to Earth until 2003, six years after Galileo stopped sending data from Jupiter.
All these issues—budgetary changes brought about by the end of the Cold War, mission failures, predicted gaps in scientific data return—meant that future space-science research and planetary exploration would require a different approach.
In the mid-1980s, with new developments in microelectronics and software, engineers could package more capability into smaller satellites. Funding from the DOD Advanced Research Projects Agency, the Air Force Space Test Program, and university laboratories allowed engineers to build low-profile, low-cost satellites with maximum use of existing components and off-the-shelf technology and minimal nonrecurring developmental effort. Research organizations, private businesses, and academic institutions—all weary of waiting years for their instruments to be piggybacked on large satellites—began to develop small satellites that could be launched as secondary payloads on the shuttle or large expendable boosters.
Small space systems were emerging that were affordable and easy to use, and thus attractive to a larger, more diverse customer base. A new trend had taken shape, and a whole new era in the history of space science was beginning.