Deep Space 2, also known as "Mars Microprobe," was the second spacecraft developed under the NASA New Millennium Program to flight-test advanced technologies concepts for space missions. The purpose of the program was to do high-risk technology demonstration, with a motto "Taking risks to reduce future danger." The Deep Space 2 mission was intended to do an engineering validation of the concept of a penetrator probe, impacting the planet at high velocity, instead of slowing down for a soft landing as done by the probes conventionally used for planetary exploration. The penetrator concept is potentially a lower-cost approach, and has a proposed advantage of giving access to the subsurface of the planet being studied
Spacecraft
Each probe weighed and was encased in a protective aeroshell. They rode to Mars aboard another spacecraft, the Mars Polar Lander. Upon arrival near the southpolar region of Mars on December 3, 1999, the basketball-sized shells were released from the main spacecraft, plummeting through the atmosphere and hitting the planet's surface at over. On impact, each shell was designed to shatter, and its grapefruit-sized probe was to punch through the soil and separate into two parts. The lower part, called the forebody, was designed to penetrate as far as into the soil. The upper part of the probe, or aftbody, was designed to remain on the surface in order to radio data to the Mars Global Surveyor spacecraft in orbit around Mars. The Mars Global Surveyor would act as a relay in order to send the data collected back to Earth. The two sections of the probe were designed to remain connected via a data cable.
Mission failure
The probes reached Mars along with the Mars Polar Lander mission, apparently without incident, but communication was never established after impact. It is not known what the cause of failure was. A failure review board was commissioned to report on the failures of the Mars Polar Lander and Deep Space 2 probes. The review board was unable to identify a probable cause of failure, but suggested several possible causes:
The probe radio equipment had a low chance of surviving the impact.
The batteries may have failed on impact.
The probes may have bounced on impact.
The probes may have landed on their sides, resulting in bad antenna performance or radio link geometry.
The probes may simply have hit ground that was too rocky for survival.
The batteries on the probes, which had been charged prior to launch almost a year earlier, might not have retained sufficient power.
The board concluded that the probes and their components were not tested adequately before launch.
