NASA’s deep space 1 probe launched in 1998, was the first craft to use ion technology in space. It flew close to the near-Earth asteroid Braille (also known as 1992 KD), guided by an automated navigation system. Afterwards, it investigated the comet Borrelly, completing its mission in late 2001. Deep Space 1 is an experimental craft that is also testing several other new technologies, including more efficient solar panels, and an autonomous operations system, which allows the craft to think and act on its own. Its success has made scientists optimistic about the use of ion technology.
Deep Space 1 is the first interplanetary spacecraft to use an ion propulsion system for the primary delta-v maneuvers. The purpose of the mission is to validate a number of technologies, including ion propulsion and a high degree of spacecraft autonomy, on a flyby of an asteroid and two comets. The ion propulsion system has operated for a total of 3500 hours at engine power levels ranging from 0.48 to 1.94 kW and has completed the encounter with the asteroid 1992KD and the first set of deterministic burns required for a 2001 encounter with comet Wilson-Harrington. The system has worked extremely well after an initial grid short was cleared after launch. Operation during this primary mission phase has demonstrated all ion propulsion system and autonomous navigation functions. All propulsion system operating parameters are very close to the expected values with the exception of the thrust at higher power levels, which is about 2 percent lower than that calculated from the electrical parameters. This paper provides an overview of the system and presents the first flight validation data on an ion propulsion system in interplanetary space
Originally designed to test a dozen new technologies including the use of an ion engine for spacecraft propulsion, Deep Space 1 far outstripped its primary mission goals by also successfully flying by the asteroid 9969 Braille and comet Borrelly. The flybys produced what are still considered some of the best images and data ever collected from an up-close encounter with an asteroid or comet.
The success of Deep Space 1 set the stage for future ion-propelled spacecraft missions, especially those making the technically difficult journey to asteroids or comets, such as NASA’s Dawn mission.
July 29, 1999: Having completed its technology testing within the first couple months after launch, Deep Space 1 makes a bonus flyby of the asteroid 9969 Braille, flying within about 17 miles (27 kilometers) of the object.
November 1999: While embarking on a new journey to comet Borrelly, the spacecraft’s star tracker used for determining its orientation in the zero gravity of space fails, nearly ending Deep Space 1’s extended mission.
June 2000: Engineers develop a new way to operate the Deep Space 1 spacecraft after the potentially mission-ending failure of its star tracker. Software is radioed to the probe using the camera on board to serve as a replacement navigational tool. The operation marks one of the most successful robotic space rescues in the history of space exploration.
September 2001: Deep Space 1 approaches comet Borrelly, using all of its advanced science instruments to collect important data on the comet’s environment and its icy, rocky nucleus. Despite the challenges faced by the spacecraft, it’s able to snap the best up-close pictures of a comet to-date.