NASA’s Deep Space 1 mission to Asteroid Braille

On 24 October 1998, NASA launched the Deep Space 1 technology demonstration mission on top of a Delta II rocket from Cape Canaveral in Florida. Deep Space 1 was the first New Millenium mission by NASA, a testbed for demonstrating 12 bleeding-edge technologies, included a xenon ion thruster, that provided a gentle, consistent nudge instead as compared to a powerful rocket engine. Gradually, the ion propulsion increased the velocity of the spacecraft to over 4.8 kilometres per second. The thruster favoured efficiency, and a sustained push over brute power. Future explorers of the Solar System such as Dawn and Psyche would also use the innovative Ion propulsion system.

The spacecraft was also equipped with autonomous navigation that used a star tracker, and solar arrays that juiced up the batteries by concentrating the energy from the Sun. The Miniature Integrated Camera and Spectrometer (MICAS) packed UV, infrared and optical imaging capabilities into a single lightweight box. The mission was designed to visit a comet and an asteroid, which were initially 76P/West–Kohoutek–Ikemura and 3352 McAuliffe. Delays in the launch of the mission caused the ground teams to switch the targets of the mission to the asteroid 9969 Braille, and the comet 19P/Borrelly.

The mission experienced a number of technical glitches that required the ground teams to adapt quickly to dynamic situations to save the mission. Material ejected during the launch caused the ion propulsion system to short-circuit after 4.5 minutes of operations. The engines were restarted repeatedly to dislodge the material and restore normal operations. The start tracker on the device also failed, but the ground teams moved quickly to use the MICAS payload as the star tracker instead, saving the mission. The hijacking of the instrument to navigate the spacecraft resulted in disruptions in science operations of the payload.

The Deep Space 1 spacecraft was supposed to flypast asteroid Braille at a distance of only 240 metres, but because of a software crash right before the encounter, the spacecraft passed at a distance of 26 kilometres. The asteroid was not bright enough for the autonomous systems on board to capture a clear, focused image. The resulting imagery was blurry and disappointing. The flyby of the Comet Borrelly was a success though, with the spacecraft sending home stunning and clear images.

After the encounter with an asteroid and a comet, Deep Space 1 also managed to capture images of Mars from a great distance. The mission operators reverted to testing the technologies on board, and shut down the engines in 2001, leaving the communications gear turned on in case the spacecraft was required in the future. Subsequent attempts to contact Deep Space 1 have been unsuccessful. The software used by the spacecraft was also subsequently used in Stardust, Deep Impact and Mars Rovers such as Curiosity. The Deep Space 1 probe continues to orbit the Sun as a derelict.