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Mars Orbit Insertion: This IS Rocket Science

This Viking 1 orbiter image shows the thin atmosphere of Mars. The 2001 Mars Odyssey spacecraft will repeatedly brush the top of the atmosphere to lower and circularize its orbit around Mars
This Viking 1 orbiter image shows the thin atmosphere of Mars. The 2001 Mars Odyssey spacecraft will repeatedly brush the top of the atmosphere to lower and circularize its orbit around Mars.

Following carefully calculated parameters set by navigators and ground controllers, Odyssey's targeting will be fine-tuned with a "trajectory correction maneuver" involving a final whisper of hydrazine gas meted through onboard jets the size of cake-decorating nozzles.

To enter orbit, Odyssey's propellant tanks, the size of big beachballs, must first be pressurized, plumbing lines heated, and the system primed before all 262.8 kilograms of propellant (579.4 pounds) burns in exactly the right direction for 19.7 minutes.

This maneuver, called the Mars orbit insertion, will brake the spacecraft's speed, slowing and curving its trajectory into an egg-shaped elliptical orbit around the planet. In the weeks and months ahead, in a process called aerobraking, the spacecraft will repeatedly brush against the top of the atmosphere to reduce the long, 19-hour elliptical orbit into a shorter, 2-hour circular orbit of approximately 400 kilometers altitude (about 250-miles) desired for the mission's science data collection.

"All of this has to be done by remote control," says Whetsel. During the main engine firing, for instance, "there's no time for the ground (operations team) to interact with the spacecraft." The one-way light time to the spacecraft -- the time it takes a radio signal to travel from the communications dishes of the Deep Space Network here on Earth to Odyssey at Mars -- will be about 8.5 minutes during the engine firing. "By the time you see whether or not things are going well, in reality, it's essentially already done. So you have to put everything on board the spacecraft ahead of time."

<< Mars: So Close, Yet So Far Away Tapping the Aerobrake >>

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Mars Mission Risks
    Earning a Degree from the School of Hard Knocks
    Mars: So Close, Yet So Far Away
    Mars Orbit Insertion: This IS Rocket Science
    Tapping the Aerobrake
    Will it be 'Bolero' or Lucy and Ethel in the Chocolate Factory?
    'You Don't Know What You Don't Know'

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