NEAR Shoemaker

• 1. Genesis Of A Small Probe

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  Johns Hopkins University Applied Physics Laboratory built the NEAR Shoemaker spacecraft in the mid-1990s. This robotic probe was designed to study asteroid 433 Eros from close orbit over a period of one year. The mission marked the first time NASA's Discovery Program sent a small-scale spacecraft into space for less than $150 million. Development costs reached $124.9 million while total mission expenses climbed to $224 million by completion. Engineers chose 433 Eros as the primary target after discussing options like 2P/Encke and 4 Vesta. The original plan involved visiting multiple asteroids and comets before settling on this single near-Earth object.

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• 2. Mathilde Flyby And Cruise

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  NEAR launched aboard a Delta 7925-8 rocket on the 17th of February 1996. The spacecraft entered hibernation mode during most of its cruise phase until approaching asteroid 253 Mathilde. On the 27th of June 1997, at 12:56 UT, it flew within 1200 kilometers of the 61-kilometer diameter body. Imaging systems captured over 500 pictures covering 60 percent of Mathilde's surface. Gravitational data allowed scientists to calculate dimensions and mass for the dark, cratered rock. A major deep space maneuver followed on the 3rd of July 1997, reducing velocity by 279 meters per second. Earth gravity assist occurred on the 23rd of January 1998, altering orbital inclination from 0.5 degrees to 10.2 degrees.

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• 3. Crisis In Orbit Insertion

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  A critical anomaly struck on the 20th of December 1998, when the first scheduled rendezvous burn sequence aborted immediately. The spacecraft entered safe mode and began tumbling while thrusters fired thousands of times. Engineers lost contact with mission control for over 24 hours as propellant reserves dropped to zero. The incident expended 29 kilograms of fuel, nearly causing total loss of the spacecraft due to battery drain. Software and operational errors contributed to the severity though root causes remained undetermined. A new plan emerged involving a flyby of Eros on the 23rd of December 1998, at 965 meters per second distance of 3827 kilometers from center of mass. Orbital insertion finally succeeded on the 14th of February 2000, after completing a 13-month heliocentric orbit matching Eros's path.

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• 4. Five Instruments And Payload

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  The science payload included five primary instruments weighing significant mass requiring 80 watts of power. Multi-Spectral Imager provided visible images of the asteroid surface using CCD imaging detectors. NEAR IR Spectrograph covered 0.8 to 2.6-micrometer spectral range in 62 bins for mineral analysis. A three-axis fluxgate magnetometer measured magnetic fields from DC to 10 Hz supplied by Goddard Space Flight Center. X-ray/Gamma-Ray Spectrometer combined fluorescence measurements with gamma-ray detection using NaI scintillator and BGO shield. Laser rangefinder served as direct-detection single-pulse device for precise altitude readings during descent phases. Radio tracking systems estimated gravity field strength through standard tracking methods used throughout operations.

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• 5. Touchdown On Eros

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  NEAR Shoemaker executed controlled descent ending with touchdown just south of saddle-shaped feature Himeros on the 12th of February 2001. Controllers expected damage but found the spacecraft undamaged at impact speed between 1.5 and 1.8 meters per second. This event marked first successful soft landing on any asteroid surface in human history. Gamma-ray spectrometer reprogrammed post-landing collected composition data from approximately one meter above surface where sensitivity increased tenfold. Cosmic ray impacts reduced about 50 percent while signal-to-noise ratio improved dramatically compared to orbital operations. Final data signals received at 7 p.m. EST on the 28th of February 2001 before shutdown due to extreme cold conditions reaching minus 279 degrees Fahrenheit.

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