Traveling at approximately 6.9 kilometers/second and 125 kilometers above the surface, the spacecraft entered the atmosphere and was initially decelerated by using a 2.4 meter ablation heat shield, located on the bottom of the entry body, to aerobrake through 116 kilometers of the atmosphere. Three minutes after entry, the spacecraft had slowed to 496 meters per second signaling an 8.4-meter, polyester parachute to deploy from a mortar followed immediately by heat shield separation and MARDI powering on, while 8.8 kilometers above the surface. The parachute further slowed the speed of the spacecraft to 85 meters per second when the ground radar began tracking surface features to detect the best possible landing location. When the spacecraft had slowed to 80 meters per second, one minute after parachute deployment, the lander separated from the backshell and began a powered descent while 1.3 kilometers aloft. The powered descent was expected to have lasted approximately one minute, bringing the spacecraft 12 meters above the surface. The engines were then shut off and the spacecraft would expectedly fall to the surface and land at 20:15:00 UTC near 76°S 195°W in Planum Australe. Lander operations were to begin five minutes after touchdown, first unfolding the stowed solar arrays, followed by orienting the medium-gain, direct-to-Earth antenna to allow for the first communication with the Deep Space Network. At 20:39 UTC, a 45-minute transmission was to be broadcast to Earth, transmitting the expected 30 landing images acquired by MARDI and signaling a successful landing. The lander would then power down for six hours to allow the batteries to charge. On the following days, the spacecraft instruments would be checked by operators and science experiments were to begin on December 7 and last for at least the following 90 Martian Sols, with the possibility of an extended mission. On December 3, 1999, at 14:39:00 UTC, the last telemetry from "Mars Polar Lander" was sent, just prior to cruise stage separation and the subsequent atmospheric entry. No further signals were received from the spacecraft. Attempts were made by Mars Global Surveyor to photograph the area in which the lander was believed to be. An object was visible and believed to be the lander. However, subsequent imaging performed by Mars Reconnaissance Orbiter resulted in the identified object being ruled out. "Mars Polar Lander" remains lost. The cause of the communication loss is not known. However, the Failure Review Board concluded that the most likely cause of the mishap was a software error that incorrectly identified vibrations, caused by the deployment of the stowed legs, as surface touchdown.