End of mission sequence of events
Posted: September 20, 2003

On the day of impact, it will take Galileo's radio signals approximately 52 minutes to travel between the spacecraft and Earth. The time at which radio signals reach Earth indicating that an event has occurred is known as "Earth-received time." All times quoted below are in Earth-received time at the Jet Propulsion Laboratory in Pasadena, Calif. All times are Eastern Daylight Time, which is four hours behind Universal Time.

At 3:52 a.m. EDT on Sunday, Sept. 21, 2003, the 70-meter-diameter (230-foot) Deep Space Network tracking station antenna near Madrid, Spain, will listen to the spacecraft. The science instruments will be configured and begin to send their data in realtime to Earth. Galileo is at a distance of 965,000 kilometers (600,000 miles).

About eight hours later, Galileo will cross the volcanic satellite Io's orbit at a distance of 422,000 kilometers (262,000 miles). The spacecraft has ventured inside this distance only twice: as it arrived at Jupiter in 1995 and again in 2002, when it made a flyby of the small inner moon Amalthea.

By 12:42 p.m., the intensity of radiation interference will reach a point where even a bright star like Vega can no longer reliably be seen by the attitude control star scanner. The software will now be told to expect to see no more stars.

At 2:31 p.m., Galileo will be 143,000 kilometers (89,000 miles) above the clouds and the magnetometer instrument will take its final data for the mission. At this distance from Jupiter, the magnetic field is so strong that the instrument, even in its most robust configuration, would produce a signal that would be completely saturated, and of no further scientific value.

Seventeen minutes later (2:48 p.m.), the spacecraft will pass the orbit of the tiny satellite Amalthea. As the spacecraft passes Amalthea, a special measurement will be taken using the star scanner. During a previous flyby of this small body on Nov. 5, 2002, flashes of light were seen by the star scanner that might indicate the presence of rocky debris circling Jupiter in the vicinity of the satellite. Though on this final pass Galileo will not be near Amalthea, the measurement may help confirm or constrain the extent of this hypothesized orbital debris.

At about 3:17 p.m., Galileo will pass the orbits of the innermost moons, Adrastea and Metis. Galileo will be just 57,500 kilometers (35,700 miles) above the clouds, closing fast, and picking up speed. A few minutes later the Galileo Orbiter will join the Galileo probe in going closer to Jupiter than any other man-made object. At 43,000 kilometers altitude (26,725 miles), the spacecraft is now at a distance that is 1/9th of the span between Earth and its own Moon.

At 3:42 p.m. with roughly seven minutes to go, Galileo will move from day to night as it passes into Jupiter's shadow, and, one minute later, it will pass behind the limb of the giant planet as seen from Earth. Only 9,283 kilometers (5,768 miles) above the clouds, the path of the spacecraft will take it out of sight of ground controllers. The last data ever to be received from the Galileo spacecraft will now been sent. The remaining few minutes of the craft will be spent in darkness.

At approximately 3:49 p.m. (1949 GMT), Galileo will reach the end of its nearly 14-year odyssey.

Goodbye Galileo
Entry preview - Story on Galileo's demise.

Mission overview - A look back at Galileo's voyage.

Spacecraft - A technical review of the Galileo spacecraft.

Top 10 - Chart of the leading science achievements by Galileo mission.

Story on stage
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