The program's goal is to identify and test advanced technologies that will provide future spacecraft with capabilities needed to achieve important science goals. Through a series of deep space and Earth-orbiting flights, the New Millennium Program will "validate" these technologies in space-that is, either prove that they work or determine what problems may crop up. The testing of advanced technologies is the basic requirement for New Millennium Program missions; as a bonus, missions can also collect science data as new instrument technologies are put through their paces.

The first New Millennium mission to launch was Deep Space 1, whose picture-perfect liftoff on Oct. 24 culminated many months of test and assembly. Unlike the typical mission that enters a cruise phase after launch, this mission began testing its new technologies immediately. In fact, two of them-large solar arrays and a new radio transmitter/receiver-were functionally validated within just two hours of launch.

A much-watched technology on Deep Space 1 is its ion propulsion system, which combines the gas xenon with some of the technologies that make television picture tubes work. Despite an almost imperceptible level of thrust, over the long haul Deep Space 1's ion engine can deliver up to 10 times more thrust than a conventional liquid or solid fuel rocket for a given amount of fuel. It has since been turned on and off repeatedly, performing beyond expectations throughout.

Deep Space 1's other new technologies, many of which have already been validated, include autonomous optical navigation, several microelectronics experiments, and software to plan and execute many onboard activities with only general direction from the ground. Two science instruments-one combining a camera, ultraviolet imaging spectrometer and infrared imaging spectrometer, the second combining several instruments that study space plasma-will be further tested during a planned flyby of asteroid 1992 KD this July. By Dec. 1, Deep Space 1 had accomplished enough testing to satisfy the technology validation aspects of the minimum mission success criteria and is now well on its way toward meeting maximum criteria as well.

Following its Jan. 3 launch, Deep Space 2's two small probes will reach Mars this December and will crash into the Martian soil to test new technologies and conduct science experiments. Each probe, approximately the size of a large grapefruit inside a basketball-sized aeroshell, contains a suite of miniature electrical and mechanical systems that must withstand extreme environments, including crashing into the planet's surface at speeds of up to 500 mph and surviving extremely low temperatures. Upon impact, they will begin collecting data to verify the survival of the penetrator system, which contains 10 new technologies.

Within the first six hours, they will also attempt to detect the presence of water ice. If successful, this mission will pave the way for future science projects involving scores of microinstruments sent to all regions of a solar system planet or moon.

The probes' three parts-a forebody that pierces up to nine-tenths of a meter (three feet) into the ground, an aftbody that remains above the ground (tethered to the forebody for telecommunications) and the aeroshell in which they are traveling to Mars-were delivered to the Kennedy Space Center this fall and attached to the Mars Polar Lander cruise ring, on which they are piggybacking to the red planet. Launch was the crowning touch to an intensive year of test and assembly for the mission team.

Deep Space 3, a proposed optical interferometry mission involving spacecraft orbiting the Sun in formation, made significant progress in 1998, as the mission was reconfigured from three spacecraft to two. Engineering design experiments determined that separated spacecraft interferometry could be accomplished using two spacecraft separated by up to one full kilometer. This change has yielded both cost and mass savings. An industry partner is scheduled to be selected and on contract by this March. Deep Space 3, which is scheduled to launch in December 2001, will undergo system requirements and architecture review in August.

Deep Space 4/Champollion, a proposed mission that will send a lander to the nucleus of comet Tempel 1 in 2005 following a scheduled launch in 2003, achieved many milestones in 1998. The team continued working on the detailed design of the lander and mother ship, including the construction of a striking, full-scale mockup of the diminutive lander. An observational program on Tempel 1 has revealed the size of the nucleus to be 3.9 by 2.8 kilometers; the team is now trying to determine additional information on the nucleus' shape and its rotation period. A NASA review is scheduled for April.

Earth Orbiter 1, New Millennium's first Earth orbiter flight, will validate technologies for future land-imaging missions. Over the course of this mission, launching in December 1999, three new land-imaging instruments will collect multispectral and hyperspectral scenes in coordination with the Enhanced Thematic Mapper (ETM+) on Landsat-7. Managed by NASA's Goddard Space Flight Center, EO-1 will demonstrate breakthrough technologies in lightweight materials, high-performance integrated detector arrays and precision spectrometers. Detailed comparisons of the EO-1 and ETM+ images will be carried out to validate these instruments for future missions.

In 1998, EO-1's advanced land imager completed environmental testing and is now in final calibration. Its Hyperion instrument was added in May and is now being fabricated; this unique instrument's capabilities provide resolution of surface properties into hundreds of spectral bands, versus the 10 multispectral bands flown on traditional Landsat imaging missions. Other instruments delivered for integration and test included EO-1's pulsed plasma thruster, carbon-carbon radiator, X-band phased array antenna, lightweight flexible solar array and enhanced formation flying software.

With Earth Orbiter 2, New Millennium will fly an infrared laser in the cargo bay of the space shuttle to see if a space-based sensor can accurately measure global winds within Earth's atmosphere from just above the surface to a height of about 16 kilometers (10 miles). Successful measurements in this key region of the atmosphere could lead to improved weather forecasting and better understanding of such climate-related events as El Nino.

Based on technology tested aboard research aircraft, the Space-Readiness Coherent Lidar Experiment (Sparcle) will detect the frequency shift of an eye-safe laser pulse as it reflects off dust and aerosol particles as they move with the winds. The resulting measurements should give researchers precise information about the speed, direction and vertical profile of tropospheric winds. Due to launch in 2001, Sparcle is managed by NASA's Marshall Space Flight Center. This year's milestones included a preliminary system design review in October, to be followed by a critical design review this April.