UA Mars mission blazes on after first course correction

The flat-topped lander carrying the University of Arizona-run science experiments that will look for signs of habitability and study Mars' climate has covered roughly 20 million of its 420-million-mile trip.

Phoenix got orders from Earth, via the Deep Space Network, to tweak its heading Friday, six days after launch. The course correction was required because the craft was deliberately not pointed directly at Mars on launch, said Mars Phoenix Mission Project Manager Barry Goldstein, of the Jet Propulsion Lab in Pasadena, Calif.

If the rocket carrying the spacecraft were pointed directly at Mars on takeoff, Goldstein said the jettisoned stages — the burned-out rockets that pushed it into Earth orbit and beyond — could hit Mars, something they want to avoid in the name of avoiding contamination of the planet. The lander itself was meticulously sterilized, to avoid bringing any life from Earth.

Goldstein said Friday's course correction involved a 198-second burn of the spacecraft's trajectory course correction rockets, by far the largest of six planned course corrections before the planned May 25, descent, entry and landing.

He said the maneuver slowed the spacecraft's velocity — relative to Earth — from 12,600 mph to 12,300 mph.

A radio signal constantly broadcast from the spacecraft is used to determine its speed and position, said Goldstein. Determining its path is an incredibly complicated calculation that has to take into account the changing gravitational effect of the bodies — even asteroids — that tug on the spacecraft.

For instance, Goldstein said the increasing gravitational pull of Mars on Phoenix as it gets closer will dramatically increase its speed.

Because Earth and Mars are not traveling in concentric orbits, Phoenix doesn't take a straight path from one planet to the other.

Meanwhile, at the UA's Phoenix Mars Science Operations Center, near North Sixth Avenue and Drachman Avenue, scientists and technicians are preparing to operate the lander's instruments after touchdown on Mars.

The science team's focus right now is on an upcoming "dress rehearsal" of operations after the landing, said UA mission spokeswoman Sara Hammond.

Hammond described the tests as a "run through, as if lander is already on Mars and we run through evaluating data, discussing what the lander will do the next day."

Then, she said, commands are designed to make the instruments carry out the next day's chores, which would then be relayed to the spacecraft.

After the landing, that routine will be repeated daily for the craft's expected three months of operation, after which scientists and technicians expect it to be crippled by Martian winter and an accompanying thick coating of carbon dioxide ice.

Beside the drills, Hammond said Phoenix Mars Principal Investigator Peter Smith and science team members are involved in teleconferences with other scientists and organizations involved in the mission.

Other institutions involved in Phoenix's science mission include the Canadian Space Agency, the Max Planck Institute (Germany), the University of Neuchatel (Switzerland) and the University of Copenhagen.

On StarNet: Find more news, videos and slide shows about Mars at azstarnet.com/mars

You can't Ride Along, but …

The UA's Phoenix Mars Mission Web site — http://phoenix.lpl.arizona.edu/ — is using JPL's Solar System Simulator to show visitors where the Phoenix Mars Mission spacecraft is relative to Mars, Earth and the sun.

Just go to the PMM main page and scroll down the right side and click on the "Where is Phoenix?" link.

The Phoenix Mars Scout Mission seeks answers to these questions:

• Can the Martian arctic support life?

• What is the history of water at the landing site?

• How is the Martian climate affected by polar dynamics?