There is scant public information on why Space Shuttle Columbia disintegrated on reentry. A technical investigation is underway, and the shuttle fleet is temporarily grounded. Human exploration of space may pause, undergo a course correction, but should not stop. It is our destiny.
The way to deorbit a spacecraft is to slow it down. Increasing drag by gases and particles in the air heats a vehicle as it drops in altitude. Deceleration produces hypergravity forces on the vehicle, equipment, and occupants. Safely landing a spacecraft thus requires special engineering considerations.
As a result of Sputnik’s launch by the Soviets on October 5, 1957, President Eisenhower committed space exploration to a civilian host, the National Advisory Committee for Aeronautics, originally formed in 1915 and housed primarily at Langley Field in southern Virginia. NACA was renamed, and on October 1, 1958 National Aeronautics and Space Administration became operational.
Getting to space then rested on enhancing ballistic-missile capability. A capsule with a pilot and life-support environment would be boosted by missile to space. The shape of the vehicle, with its broad, blunt bottom would be shielded so that the vehicle and occupants could withstand the heat of reentry. Suggested by aerodynamics experts like Alfred Eggers and Harvey Allen — who were motivated by shapes of air-ablated meteorites — the concept was developed by NACA and NASA scientists into the Mercury, Gemini, and Apollo capsules.
During reentry, retro-rockets would slow and therefore lower the vehicle toward earth under gravity’s pull. The shielded end would protect against the heat of reentry, and parachutes would slow the capsule for a safe splashdown in the water. Reentry anxiety arose during John Glenn’s flight when ground stations received a false signal that the airbag had deployed during orbit. That signal suggested that the heat shield might not be properly seated for safe return. The signal was faulty and reentry successful. Perhaps the most frightening reentry — prior to Columbia’s disintegration — was that of the damaged Apollo 13 vehicle returning safely from lunar orbit.
The 1960s capsules and their Redstone, Atlas, Titan, or Saturn rockets could not be reused. Post-Apollo, reusable rockets and capsules, integrated into a space-plane, seemed more cost-effective.
Thus evolved the idea of the space shuttle, a vehicle meant to return to space many times. Reentry still requires a blunt surface protected by heat shielding — hence, the tiles on the broad belly of the craft — but landing is now on ground rather than on the ocean. The winged shuttle flies more capably than a capsule in order to glide safely to the ground.
NASA’s top priority is to bring astronauts home safely; the will and resources to lower the risks to crews must remain high priority to our space-faring society.
Funding for space travel has become a persistent worry, if not problem. Historically, NASA’s budget has suffered two significant reductions. The first took place during and after Apollo, when spending dropped from its high in the mid-1960s of approximately 0.8 percent of GDP to 0.2 percent of GDP by the early 1970s. During the 1990s, the NASA budget as a fraction of GDP slowly fell; by the end of that decade the erosion in real dollars had been about one-third, meaning NASA either does less or does more with less funding. Federal spending may mirror public opinion, which in some opinion polls has been demanding more benefits for the program cost. (This seems odd considering the rapid growth in the U.S. dependency on near space — e.g., defense intelligence, satellite communications, weather forecasting, environmental resource imagery, entertainment broadcasting and navigation.)
After experiments aboard the International Space Station help establish benchmarks on human exposure to microgravity and other harsh conditions of space, humans must look to the future. It may be time to begin to build the next generation in space transportation, made even safer through the decades of experience gained in space travel. There should be human missions again to the moon, then human-tended lunar bases and explorations of Mars.
“All this writing about space travel is utter bilge. To go to the moon would cost as much as a war.” So explained the Astronomer Royal of Britain, Sir Richard Woolley in 1956, less than a year before Sputnik’s launch.
Sir Woolley was nearly correct, but ultimately wrong. What undermined Woolley’s premise were the Sputnik and its implication of Soviet supremacy of the near-earth environment. That and the grit of a young president generated the war-sized resources to reach the moon.
If NASA continues to fly humans in space, then appropriate resources for risk reduction are necessary, but need not be with war-sized budgets or urgency. The lack of urgency leaves room for cost-effective programs.
Exploration of the unknown is an inherent drive of Homo sapiens, perhaps part of a survival strategy in our genetic heritage. New arenas may give the species access to resources that improve survival, despite the risk to an individual’s genetic reproductive success. Risk-free space exploration is impossible. Risk reduction is an obligation of a space-faring society.
Risk we must. The fruits of space-based Homo sapiens remain ever unpredictable, but the journey is essential. All astronauts are human, and they are we.
— Sallie Baliunas, an astrophysicist, co-hosts www.TechCentralStation.com and is a senior scientist at the Marshall Institute.