The Mars Surveyor '98 program is comprised of two spacecraft launched separately, the MCO (Mars Climate Orbiter, formerly the Mars Surveyor '98 Orbiter) and the MPL (Mars Polar Lander, formerly the Mars Surveyor '98 Lander). The two missions were to study the Martian weather, climate, and water and carbon dioxide budget, in order to understand the reservoirs, behavior, and atmospheric role of volatiles and to search for evidence of long-term and episodic climate changes. The Mars Climate Orbiter was destroyed when a navigation error caused it to miss its target altitude at Mars by 80 to 90 km, instead entering the Martian atmosphere at an altitude of 57 km during the orbit insertion maneuver.