NASA,John Glen

Article Outline

Exploration

History

Science

Politics

Future

    The future of space exploration depends on many things. It depends on how technology evolves, how political forces shape rivalries and partnerships between nations, and how important the public feels space exploration is. The near future will see the continuation of human spaceflight in Earth orbit and unpiloted spaceflight within the solar system. Piloted spaceflight to other planets, or even back to the Moon, still seems far away. Any flight to other solar systems is even more distant, but a huge advance in space technology could propel space exploration into realms currently explored only by science fiction.

Piloted Spaceflight
    The 1968 film 2001: A Space Odyssey depicted commercial shuttles flying to and from a giant wheel-shaped space station in orbit around Earth, bases on the Moon, and a piloted mission to Jupiter. The real space activities of 2001 will not match this cinematic vision, but the 21st century will see a continuation of efforts to transform humanity into a spacefaring species.

    The International Space Station was scheduled to become operational in the first years of the new century. NASA plans to operate the space shuttle fleet at least through the year 2012 before phasing in a replacement—possibly a single-stage-to-orbit (SSTO) vehicle. However, some experts predict that the SSTO is too difficult a goal to be achieved that soon, and that a different kind of second-generation shuttle would be necessary—perhaps a two-stage, reusable vehicle much like the current shuttle. In a two-stage launcher, neither stage is required to do all the work of getting into orbit. This results in less stringent specifications on weight and performance than are necessary for an SSTO.

    Perhaps the most difficult problem space planners face is how to finance a vigorous program of piloted space exploration, in Earth orbit and beyond. In 2001 no single government or international consortium had plans to send people back to the Moon, much less to Mars. Such missions are unlikely to happen until the perceived value exceeds their cost.

    Some observers, such as Apollo 11 astronaut Buzz Aldrin, believe the solution may lie in space tourism. By conducting a lottery for tickets on Earth-orbit “vacations,” a nonprofit corporation could generate revenue to finance space tourism activities. In addition, the vehicles developed to carry passengers might find later use as transports to the Moon and Mars. Several organizations are pushing for the development of commercial piloted spaceflight. In 1996 the U.S. X-Prize Foundation announced that it would award $10 million to the first private team to build and fly a reusable spacecraft capable of carrying three individuals to a height of at least 100 km (62 mi). By 2000, 16 teams had registered for the competition, with estimates of first flights in 2001.

    One belief shared by Aldrin and a number of other space exploration experts is that future lunar and Martian expeditions should not be Apollo-style visits, but rather should be aimed at creating permanent settlements. The residents of such outposts would have to “live off the land,” obtaining necessities such as oxygen and water from the harsh environment. On the Moon, pioneers could obtain oxygen by heating lunar soil. In 1998 the Lunar Prospector discovered evidence of significant deposits of ice—a valuable resource for settlers—mixed with soil at the lunar poles. On Mars, oxygen could be extracted from the atmosphere and water could come from buried deposits of ice.

    The future of piloted lunar and planetary exploration remains largely unknown. Most space exploration scientists believe that people will be on the Moon and Mars by the middle of the 21st century, but how they get there—and the nature of their visits—is a subject of continuing debate. Clearly, key advances will need to be made in lowering the cost of getting people off Earth, the first step in any human voyage to other worlds.

Unpiloted Spaceflight
    The space agencies of the world planned a wide array of robotic missions for the final years of the 20th century and the opening decade of the 21st century. NASA's Mission to Planet Earth (MTPE) Enterprise is designed to study Earth as a global system, and to document the effects of natural changes and human activity on the environment. The Earth Observing System (EOS) spacecraft form the cornerstone of the MTPE effort. Terra, the first EOS spacecraft, was launched in December 1999. It began providing scientists with data and images in April 2000.

    Mars will be visited by a succession of landers and orbiters as part of NASA's Discovery Program, of which the Mars Pathfinder lander was a part. The program suffered setbacks in 1999 that jeopardized NASA's goal of retrieving a sample of Martian rocks and soil in 2003 and bringing it to Earth. Although NASA planned future missions to Mars, the missions may face delays as engineers work to ensure they do not lose more spacecraft to human error or inadequate testing.

    The Discovery program also includes the Near Earth Asteroid Rendezvous mission (NEAR). This spacecraft entered orbit around the asteroid Eros in 2000. In 2004 a spacecraft called Stardust, launched on February 7, 1999, is scheduled to fly past Comet Wild 2 (pronounced Vilt 2) and gather samples of the comet's dust to bring back to Earth (see Comet).

    The Discovery program also includes the Near Earth Asteroid Rendezvous mission (NEAR). This spacecraft entered orbit around the asteroid Eros in 2000. In 2004 a spacecraft called Stardust, launched on February 7, 1999, is scheduled to fly past Comet Wild 2 (pronounced Vilt 2) and gather samples of the comet's dust to bring back to Earth (see Comet).

    Jupiter's moon Europa is also likely to receive increased scrutiny, because of strong evidence for a liquid-water ocean beneath its icy crust. Among the missions being studied is a lander to drill through the ice and explore this suspected ocean. As with Mars, scientists are especially eager to find any evidence of past or present life on Europa. Such investigations will be difficult, but the discovery of any form of life beyond Earth would undoubtedly spur further explorations.

    Saturn will be visited by the Cassini orbiter in the summer of 2004. The spacecraft is to deploy a probe called Huygens that will enter the atmosphere of Saturn's largest moon, Titan, in December 2004. During its trip to the surface, Huygens will analyze the cloudy atmosphere, which is rich in organic molecules.

    NASA is also considering orbiters to survey Mercury, Uranus, and Neptune. Pluto, the only planet that has never been visited by a spacecraft, is the target for a proposed Pluto Express mission. A pair of lightweight probes would be launched at high speed, reaching Pluto and its moon Charon as early as 2010.

    NASA's New Millennium program is aimed at creating new technologies for space exploration and swiftly incorporating them into spacecraft. In its first mission, the Deep Space 1 spacecraft used solar-electric propulsion to fly by an asteroid in July 1999 and was scheduled to visit comet Borelly in 2001.

    NASA also plans a number of orbiting telescopes, such as the Chandra X-Ray Observatory, an X-ray astronomy telescope launched from the space shuttle in 1999. Another program, called Origins, is designed to use ground-based and space-borne telescopes to search for Earthlike planets orbiting other stars.

International Cooperation
    Space exploration experts have long hoped that as international tensions have eased, an increasing number of space activities could be undertaken on an international, cooperative basis. One example is the International Space Station. In 1998, however, countries and agencies such as Japan and the European Space Agency (ESA) began to reassess their commitments to space exploration because of economic uncertainty. The transportation system for this mission may involve Russian space hardware, such as the Soyuz spacecraft.

    In addition to the economic savings that could result from nations pooling their resources to explore space, the new perspective gained by space voyages could be an important benefit to international relations. The Apollo astronauts have said the greatest discovery from our voyages to the Moon was the view of their own world as a precious island of life in the void. Ultimately that awareness could help to improve our lives on Earth.