Near Earth Asteroid Rendezvous (NEAR) mission was the first of NASA's Discovery missions, a series of small-scale spacecraft designed to proceed from development to flight in under three years for a cost of less than $150 million. The spacecraft's mission was to rendezvous with and achieve orbit around the asteroid Eros in January 1999, and study the asteroid for one year. However as it flew by the Earth on 23 January 1998, a problem caused an abort of the first encounter burn. The mission had to be rescoped for a later encounter but successfully entered orbit around Eros on Valentine's Day 2000 and ended the mission by gently landing on its surface on 12 February 2001.
The Lunar Prospector was designed for a low polar orbit investigation of the Moon, including mapping of surface composition and possible polar ice deposits, measurements of magnetic and gravity fields, and study of lunar outgassing events. Data from the 1 to 3 year mission will allow construction of a detailed map of the surface composition of the Moon, and will improve understanding of the origin, evolution, current state, and resources of the Moon. After launch, the Lunar Prospector had a 105 hour cruise to the Moon, followed by insertion into a near-circular 100 km altitude lunar polar orbit with a period of 118 minutes. The nominal mission duration was one year.
Stardust was to fly within 100 km of comet 81P/Wild-2 in January 2004 and recover cometary material using an aerogel substance. A return capsule would land on a lake bed in Utah in January 2006, returning the material to earth. The launch went as planned. The second stage ignited at 21:08 GMT and its first burn put the vehicle into a 185 km x 185 km x 28 degree parking orbit at 21:14 GMT. The second stage second burn at 21:25 changed the orbit to planned values of 178 km x 7184 km x 28.5 degrees. The Star 37FM solid third stage ignited at 21:29 GMT and placed the spacecraft into a 2 year period solar orbit. The spacecraft separated at 21:31 GMT. Meanwhile, the Delta 266 second stage burned a third time on its own, until its propellants were depleted, entering a final orbit of 294 km x 6818 km x 22.5 degrees. The Stardust probe flew past Earth at a distance of 3706 km at 1115 GMT on January 15, 2001, and flew near the Moon at a distance of 98000 km at around 0200 GMT on January 16. The gravity assist flyby changed Stardust's heliocentric orbit from 0.956 x 2.216 AU x 0.0 deg to 0.983 x 2.285 AU x 3.7 deg.
Launch delayed from February 10 and July 30. The Genesis probe flew to the Earth-Sun L1 Lagrangian point and spend two years collecting samples of the solar wind. The collected samples were to be physically returned to Earth in a sample return capsule (air-snatch recovery was planned over Utah) and analysed in ground-based laboratories. The first burn of the Delta second stage put Genesis in a 185 x 197 km x 28.5 deg parking orbit at 1624 GMT. At 1712 GMT a second burn raised the orbit to 182 x 3811 km, and at 1713 GMT the third stage fired to put Genesis on its trajectory to L1 with a nominal apogee of around 1.2 million km. By the first week of November 2001 Genesis arrived at the Earth-Sun L1 point. A malfunctioning thermal radiator caused some concern for the health of the sample return capsule's critical battery, which was overheating, but Genesis began collecting solar wind samples on schedule.
On September 8, 2004, the Genesis space probe became the first spacecraft to return from beyond lunar orbit to the Earth's surface. The Genesis Sample Return Capsule separated from the spacecraft on September 8, 66,000 km above the Earth. The capsule successfully re-entered the atmosphere over Oregon at 11 km/s, but a wiring error resulted in the drogue parachute release mortar failing to fire at 33 km altitude. The capsule crashed to earth at 90 m/s in the Dugway Proving Ground at 40 07 40 N 113 30 29 W. Although the vehicle was smashed, some of the samples could be retrieved.
Launch delayed from July 1st. The latest NASA Discovery mission was successfully launched on Jul 3. The CONTOUR (Comet Nucleus Tour) probe, built and operated by the Johns Hopkins University's Applied Physics Laboratory (APL), began its five year mission to explore three comets, using repeated encounters with the earth to modify its orbit in order to reach each target. The first burn of the second stage completed at 0659 UTC putting the spacecraft in a 185 x 197 km x 29.7 deg parking orbit. At 0746 UTC the second stage restarted for a short 4s burn to 185 x 309 km x 29.7 deg, and then separated once the PAM-D (ATK Star 48B) solid third stage was spun up. The 1.5 minute burn of the third stage motor at 0748 UTC put it and CONTOUR in a 90 x 106689 km x 30.5 deg phasing orbit. By July 8 CONTOUR's orbit was 214 x 106686 km x 29.8 deg. CONTOUR stayed in this phasing orbit until August 15, when it was injected into solar orbit using its internal ATK Star 30 solid motor. Flyby of the first target, comet 2P/Encke, was scheduled for Nov 2003.
The NASA Messenger probe to Mercury was was first placed into a parking orbit. The Delta booster second stage's second burn raised the orbit, then the PAM-D solid motor burned to put the probe on an escape trajectory into a 0.92 x 1.08 AU x 6.4 deg heliocentric orbit. Messenger (Mercury Surface, Space Environment, Geochemistry and Ranging) was to make an Earth flyby on August 1, 2005; Venus flybys in 2006 and 2007; and Mercury encounters in January and October 2008 , September 2009 and March 2011 . On this last encounter the Aerojet 660N engine was to fire to put Messenger into a 200 x 15,193 km x 80 deg orbit around Mercury. Launch delayed from March 10, May 11, August 2
Launched into a 0.981 AU x 1.628 AU solar orbit inclined 0.6 deg to the ecliptic. Deep Impact was to fly by Comet 9P/Tempel-1 on 3 July 2005. An impacter it released was to hit the comet on 4 July at 10.2 km/s, producing a crater and ejecta plume that would allow the flyby spacecraft to determine the composition and structure of the comet's nucleus.