First Ion Burn Completed

Ground controllers commanded Deep Space 1 to turn off thrusting of its ion engine this week, allowing them to perform critical tests of two of the mission’s advanced technologies.

The ion engine was turned off Tuesday, December 8, after a
marathon period of two weeks of thrusting. While operating, the
ion engine ran more than twice as long as it was originally
planned to thrust without interruption at any time during the
mission. By running the ion engine for more than 200 hours and
successfully conducting technology validation of the spacecraft’s
solar array and transponder (radio transmitter/receiver), the
team achieved the minimum criteria that NASA established for
overall mission success.

With the ion engine off, the team was able to activate one
of the mission’s two advanced science instruments, the Plasma
Experiment for Planetary Exploration (PEPE). This involved a
complex series of activities Tuesday and Wednesday. The advanced
instrument, which has no moving parts, is now fully powered up
and will be left on indefinitely.

The team was also able to test another of the mission’s
advanced technologies, the Ka-band solid-state power amplifier.
On Tuesday and Wednesday nights, Deep Space 1 sent data to Earth
in the Ka band at a frequency four times higher than that used
for most communications with solar system exploration spacecraft
today, transmitting to a ground station of the Deep Space Network
at Goldstone, California. Deep Space 1 also sent data in the
lower-frequency X band using its high-gain antenna for the first
time. During the tests, the spacecraft’s transponder sent
telemetry at 14 different data rates.

On Friday, the team will command Deep Space 1 to resume ion
engine thrusting. Plans call for the ion engine to operate
nearly continuously until January. The spacecraft will suspend
thrusting from January to March in order to conduct other
technology validation activities and to help shape its flight
path for its flyby of asteroid 1992 KD in July 1999.

Deep Space 1 is now 7.6 million kilometers (4.7 million
miles) from Earth, or more than 19 times as far away from Earth
as the Moon is. Radio signals traveling at the speed of light
take about 50 seconds to make the round trip.