Camera On Mars Orbiter Snaps Phoenix During Landing

The image from the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter marks the first time ever one spacecraft has photographed another one in the act of landing on Mars.

Meanwhile, scientists pored over initial images from Phoenix, the first ever taken from the surface of Mars' polar regions. Phoenix returned information that it was in good health after its first night on Mars, and the Phoenix team sent the spacecraft its to-do list for the day.

"We can see cracks in the troughs that make us think the ice is still modifying the surface," said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson. "We see fresh cracks. Cracks can't be old. They would fill in."

Camera pointing for the image from HiRISE used navigational information about Phoenix updated on landing day. The camera team and Phoenix team would not know until the image was sent to Earth whether it had actually caught Phoenix.

"We saw a few other bright spots in the image first, but when we saw the parachute and the lander with the cords connecting them, there was no question," said HiRISE Principal Investigator Alfred McEwen, also of the University of Arizona.

"I'm floored. I'm absolutely floored," said Phoenix Project Manager Barry Goldstein of NASA's Jet Propulsion Laboratory, Pasadena, Calif. A team analyzing what can be learned from the Phoenix descent through the Martian atmosphere will use the image to reconstruct events.

HiRISE usually points downward. For this image, the pointing was at 62 degrees, nearly two-thirds of the way from straight down to horizontal. To tilt the camera, the whole orbiter must tilt. Mars Reconnaissance Orbiter was already pointed toward the expected descent path of Phoenix to record radio transmissions from Phoenix.

McEwen said, "We've never taken an image at such an oblique angle before."

The landing

From a distance of about 760 kilometers (472 miles) above the surface of the Red Planet, Mars Reconnaissance Orbiter pointed its HiRISE obliquely toward Phoenix shortly after it opened its parachute while descending through the Martian atmosphere. The image reveals an apparent 10-meter-wide (30-foot-wide) parachute fully inflated. The bright pixels below the parachute show a dangling Phoenix. The image faintly detects the chords attaching the backshell and parachute. The surroundings look dark, but corresponds to the fully illuminated Martian surface, which is much darker than the parachute and backshell.

Phoenix released its parachute at an altitude of about 12.6 kilometers (7.8 miles) and a velocity of 1.7 times the speed of sound.

The tasks for May 27 for Phoenix include checkouts of some instruments and systems, plus additional imaging of the lander's surroundings.