Team Delights In Spot-On Landing

296 days after its launch aboard a Delta II launch vehicle, the Phoenix Mars Lander successfully landed on the Martian surface at 1653 PDT with a soft touchdown as planned.
 
Assisted by communications relays from the Mars Reconnaissance Orbiter and Mars Odyssey, the team at NASA's Jet Propulsion Laboratory, Pasadena, CA said that the landing sequence went as smooth as could be imagined. The mood was tense as the team awaited word on each stage of the system through the 15 minute delay between transmission and receipt of the signal on earth.

After months during the cruise phase filled with testing of procedures, equipment and software in preparation for arrival at Mars the spacecraft completed the 121 million mile journey that started on August 4 of last year. During the course of the cruise phase the Phoenix had six opportunities to fire thrusters to adjust trajectory to assure the "arrow hit the target."

Mission controllers decided Saturday night and Sunday morning to forgo the last two opportunities for adjusting the spacecraft's trajectory.

"We were so well on course that those adjustments were not necessary," said Phoenix Project Manager Barry Goldstein.

As ANN reported two weeks ago, tensions were high as the Phoenix neared the planet and preparations for the landing began.

The most challenging part of the entire mission, getting from the top of the atmosphere to a safe landing on three legs, was the most anticipated portion of the mission by the team. Internationally, only five of the 11 attempts to land a spacecraft on Mars have succeeded.

The intense entry, descent and landing period starting three hours before the spacecraft enters Mars' atmosphere until it reached the ground safely went according to plan. The craft hit the top of the atmosphere at a speed of 5.7 kilometers per second (12,750 miles per hour). Over the next six and a half minutes, it used heat-generating atmospheric friction, then a parachute, then firings of descent thrusters that brought velocity down to about 2.4 meters per second (5.4 miles per hour) just before touchdown.

"This team performed perfectly!" said Peter Smith Phoenix Principal Investigator with the University of Arizona team to NASA TV shortly after the landing was announced.

Unlike the last three successful landings on Mars that used airbags to cushion the impact to the surface, Phoenix used descent thrusters in the final seconds down to the surface and successfully set down onto three legs. The landing system is similar to NASA's 1976 Viking landers.

Within an hour and a half after landing, NASA awaited confirmation of the deployment of the solar array that will provide power to the Phoenix.  Once that confirmation is made by Mars Odyssy in an overflight the lander will be checked for system health and images will start being transmitted from it.

In subsequent days, when the lander has been evaluated as safe to proceed with its science mission, the center of operations will switch to the University of Arizona, Tucson. Over the next week or so, a series of checkouts will characterize the performance and readiness of the lander's subsystems and science instruments. Planned activities for this phase of the mission include using the Robotic Arm Camera to see the footpads and delivering a sample of surface soil.

The Phoenix Mars Mission is the first of NASA's competitively proposed and selected Mars Scout missions, supplementing the agency's core Mars Exploration Program, whose theme is "follow the water."

"The Phoenix mission not only studies the northern permafrost region, but takes the next step in Mars exploration by determining whether this region, which may encompass as much as 25 percent of the Martian surface, is habitable," said Smith.

The University of Arizona was selected to lead the mission in August 2003 and is the first public university to lead a Mars exploration mission.

The Phoenix mission is led by Smith, with project management at JPL. The development partnership is with Lockheed Martin, Denver. International contributions are from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; the Max Planck Institute, Germany; and the Finnish Meteorological Institute.

Original Report

1955 EDT: It's down! Moments ago, NASA received confirmation from the Mars Phoenix lander it had landed softly on the surface of the Red Planet.

"Phoenix has landed! Phoenix has landed!" Mission Control exclaimed upon termination of the EDL signal relayed to Earth through the Mars Odyssey, about 90 seconds after the orbiter signaled touchdown on the planet's surface. The signal termination marked the beginning of the lander's autonomous operations.

Radio signals are received by NASA on Earth about 15 minutes after they are transmitted from Mars. 

Confirmation of the next milestone will occur in about one hour, when Phoenix will deploy its twin circular solar panels, and the lander transmits its first pictures from the Martian surface.

FMI: www.nasa.gov/phoenix