Space Exploration

C

The High Cost of Space Exploration

One aspect of space exploration that has changed little over time is its cost. To some extent the ability to carry out a vigorous space program is a measure of a nation’s economic vitality. For example, Russia has had difficulties staying on schedule with its contributions to the International Space Station—a reflection of the unstable Russian economy.

Cost has always been a central factor in the political standing of space programs. The enormous expense of the Apollo Moon program (roughly $100 billion in 1990s dollars) prompted critics to say that the program could have been carried out far more cheaply by robotic missions. While that claim is oversimplified—no robot has yet equaled the performance of a skilled observer—it reveals how vulnerable space programs are to budget cuts. The reusable space shuttle failed to significantly lower the cost of placing satellites in low Earth orbit, as compared with throwaway launchers like the Saturn V and the Titan III. Cost, not scientific potential, is usually the most significant factor for a nation in deciding whether to adopt a major space program. In the United States budgetary process, space funding must compete in a very visible way with expenditures for social programs and other concerns. Taking inflation into account, Congress has steadily trimmed NASA’s allotments, forcing the agency to reduce its number of employees to pre-Apollo levels.

In response to the high cost of space access, the late 1990s saw renewed efforts to develop a single-stage, reusable space vehicle. The situation also strengthened arguments that in the future, the most expensive space programs should be carried out by a consortium of nations. Most scientists envision a program for sending humans to Mars as an international one, primarily as a cost-sharing measure. Still, the mix of scientific, political, and other motivations has yet to bring about such a venture, and it may be years or even decades before international piloted interplanetary voyages become reality.

V

Future of Space Exploration

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.

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A

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 the 21st century do not match this cinematic vision, but the century will see a continuation of efforts to transform humanity into a spacefaring species.

The International Space Station became operational during the first years of the new century. NASA plans to operate the space shuttle fleet through the year 2010 to help with completion of the ISS. NASA also has begun work on the Constellation Program as the next phase of human space flight after the retirement of the shuttle. Issues of cost and safety led NASA to choose a capsule and booster design similar to Apollo technology. The Orion capsule is much larger than the Apollo capsule and can carry up to six astronauts. In addition to ferrying astronauts to the ISS, Orion is intended to take astronauts back to the Moon and onto Mars.

Orion is launched on the Ares I solid-fuel rocket. The capsule has an escape system to pull the vehicle free in case of an accident during launch. The larger Ares V rocket is designed to carry cargo and space modules into orbit, where Orion can be attached to craft that will take the capsule and crew to the Moon and beyond. Plans call for establishing a Moon base after 2020, with Mars missions by 2031.

Perhaps the most difficult problem space planners face is how to finance a vigorous program of piloted space exploration, in Earth orbit and beyond. Such missions are unlikely to happen until the perceived value exceeds their cost.

Private piloted spaceflight seems poised to play a major role in the 21st century. The first privately funded spaceflights took place in 2004. One company has proposed setting up a program of space tourism, taking passengers into space for a fee. Private spacecraft may soon be used to launch satellites as well.

One belief shared by Apollo 11 astronaut Buzz 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 will likely depend on the early success of the Constellation Program and the willingness of the United States and other nations to fund and conduct technically complex human missions. 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.

B

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. However, the success of the Mars Exploration Rover Mission that began in 2004 restored confidence in NASA’s Mars program.

The Discovery program also included the Near Earth Asteroid Rendezvous (NEAR) and Stardust missions. NEAR entered orbit around the asteroid Eros in 2000 and touched down on the asteroid’s surface in 2001. Stardust, launched in February 1999, flew past Comet Wild 2 (pronounced Vilt 2) in January 2004. Stardust gathered samples of the comet’s dust and returned them to Earth in January 2006 (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.

NASA’s Cassini orbiter arrived at Saturn in the summer of 2004. The spacecraft will study the planet, its rings, and its moons. Cassini deployed a probe called Huygens that entered the atmosphere of Saturn’s largest moon, Titan, and descended to its surface in January 2005. During its trip to the surface, Huygens analyzed the cloudy atmosphere, which is rich in organic molecules, and obtained detailed images of the moon’s surface, including photographs of what appear to be drainage channels leading to a flood plain.

NASA launched the New Horizons spacecraft in January 2006 to fly by Pluto, a dwarf planet not yet visited by a spacecraft. The spacecraft may reach Pluto and its moon Charon in 2015. New Horizons would then move on to examine other icy bodies in the outer solar system called Kuiper Belt Objects (KBOs).

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 visited 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. The James Webb Space Telescope is set for launch in 2013 as the successor to the extremely successful Hubble Space Telescope. Another program, called Origins, is designed to use ground-based and space-borne telescopes to search for Earthlike planets orbiting other stars.

C

International Cooperation

Space exploration experts have long hoped that as international tensions eased, an increasing number of space activities could be undertaken on an international, cooperative basis. One example of this cooperation is the International Space Station (ISS). The United States, Russia, Canada, Japan, and the European Space Agency (ESA) have all contributed to the station’s construction.

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.

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