Technicians at Lockheed Martin Space Systems, Denver, prepare the heat shield for NASA's Mars Science Laboratory, in this April 2011 photo. With a diameter of 4.5 meters (nearly 15 feet), this heat shield is the largest ever built for a planetary mission.

The heat shield was delivered to NASA Kennedy Space Center, Fla., on May 12, 2011, together with the mission's back shell and cruise stage.

Mars Science Laboratory will launch in late 2011. The mission's rover, Curiosity, will land on Mars in August 2012. It will study whether an intriguing area of Mars has offered environmental conditions favorable for supporting microbial life and for preserving evidence of whether life existed there.

The heat shield and back shell together form the aeroshell, which will encapsulate and protect Curiosity from intense heat and friction generated during descent through the Martian atmosphere.

This view shows the inner surface of the heat shield, where technicians are installing electronics of an instrument for collecting data about temperature and pressure during descent through the atmosphere. This instrument is the Mars Science Laboratory Entry, Descent and Landing Instrument (MEDLI). It was developed by NASA's Langley Research Center, Hampton, Va., in partnership with NASA's Ames Research Center, Moffett Field, Calif.

The white area below the center of the heat shield in this view will serve for calibration of the mission's Mars Descent Imager as the heat shield drops away from the rover during descent. The camera will then record a high-definition color video of the ground until moments after touch down.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington.