Feb 12 2001
From The Space Library
The NEAR Shoemaker spacecraft landed on the 433 Eros asteroid, becoming the first probe ever to accomplish such a feat. The landing was a bonus. NEAR had already successfully completed a 1 billion-mile mission, which had provided pictures of Earth, comet Hoylake, and the asteroid 253 Mathilde. After a carefully scripted 5-hour descent, NEAR touched down safely, traveling at about 4 miles (6 kilometers) per hour. The spacecraft, which engineers had not designed for the impromptu landing mission, did not have a parachute to lessen its impact on the asteroid’s unknown surface. By firing the spacecraft’s engines five times during descent, NASA controllers were able to slow the craft to a safe landing speed. As NASA’s Chief Scientist Edward J. Weiler explained, “If you were an Erosian watching this thing come in, it should have a velocity about that of a walking individual.” Scientists landed the craft to demonstrate that the landing was possible, as well as to gather additional information. NASA engineers reported detecting a faint signal from the probe even after it had landed. The environment is harsh on the asteroid, which measures 21 miles (34 kilometers) long and 8 miles (13 kilometers) wide. Moving through space at more than 40,000 miles (64,300 kilometers) per hour, Eros reaches a temperature of 400°F (204°C) daily and has only weak gravity. Researchers believed that the asteroid is composed of material older than Earth and might have been part of another planet at one time. (Mike Toner, “Discover: Rendezvous with Eros Matchup Planned Monday for Asteroid, Spacecraft,” Atlanta Journal-Constitution (GA), 11 February 2001; Reuters, “Space Probe Set To Land on Asteroid Eros,” Washington Post, 12 February 2001; Dan Vergano, “Probe Lands on Gigantic Near-Earth Asteroid,” USA Today, 13 February 2001; Regina Holtman, “Signals from Surface,” Washington Times, 13 February 2001; Kathy Sawyer, “Spacecraft Lands on Asteroid; NASA Probe’s Historic First May Yield Wealth of Data,” Washington Post, 13 February 2001.)
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