The spacecraft has redundant systems to survive the failure of some components, and mission controllers have drawn up contingency plans for possible problems.

“Up to this point, we haven’t needed any of it,” said Edward Sedivy, the Phoenix program manager at Lockheed Martin Space Systems in Denver, which built the spacecraft.

At a news conference on Monday, NASA released a photograph made possible by another engineering tour de force. On Sunday, the Mars Reconnaissance Orbiter, passing by at an altitude of 192 miles and traveling 7,600 miles per hour, snapped a picture of the Phoenix and its billowing parachute as it descended through the Martian air to its landing site.

“This is an engineer’s delight,” said Barry Goldstein, the mission’s project manager.

On Monday morning, a new set of instructions was sent to the Phoenix, and the results, including more photographs, were expected soon. After about a week of checking out the spacecraft and its systems, the science mission will begin by digging up a soil sample. More...