“On Friday we will have the trajectory correction maneuver,” Garcia said.
This maneuver will aim Phoenix toward Mars. Garcia explained that at the initial launch, the spacecraft is actually aimed away from Mars. At launch the spacecraft is connected to nine solid rockets. After liftoff, various engines ignite, burn out and separate, with some falling into the ocean. At about 90 minutes after Saturday’s launch, the third stage separated from the spacecraft. At that point Phoenix and the third stage were two free floating bodies that continued to push off each other.
“We have little thrusters that move us away from the third stage a little at a time,” Garcia said.
At 11:30 a.m. PST today, Friday, the Phoenix will correct its trajectory and be on course for Mars. The ten-month cruise is expected to be uneventful, with a few tests along the way but a collective deep breath will be held for the landing.
“We will be doing a direct entry,” Garcia said. “We will go from 12,000 miles per hour to five mph in 400 seconds.”
This is the first time since Viking (which launched in 1975) that a soft landing will be done on the planet’s surface. The spacecraft will use a parachute to help reduce its speed, along with rocket blasts that will pulse on and off as it approaches the landing site.
“We will expect to kick up some dust,” Garcia said.
After the dust settles the mission team will then begin settling Phoenix in by unfolding the solar discs that feed its power supply. The robotic arm will also be released, the camera unstowed and the meteorological instruments prepared. Throughout, both the Mars Reconnaissance Orbiter and the Odyssey will be sending back data to JPL concerning the Phoenix landing and operations. It is not certain if MRO will use its high resolution camera to take a photo of the landing.
Phoenix will not only have a unique landing, but the location is unusual. It will land and collect data from the northern polar region of the red planet.
“[Physically] it is the most boring place on Mars,” Garcia said. “But scientifically, it is awesome.”
Phoenix will be the first to explore this area with equipment that can drill, photograph and analyze the soil around it. Unlike the rovers, Phoenix is stationary and has a limited life span. Although JPL missions consistently exceed their scheduled time of operation, it is unlikely that Phoenix will continue past its 90 Martian day schedule. This is due to the extreme cold expected, ice cap coverage and lack of sunlight. Phoenix will arrive just before the Martian summer but by winter it will be too cold and the ice caps will have returned.