Mars Surveyor '98 program

The Mars Surveyor '98 program was comprised of two spacecraft launched separately, the Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) and the 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.

Both spacecraft were launched during the 1998 Mars orbit insertion launch window. Both were lost upon arrival at the planet, the orbiter to a software error causing it to burn up in the Martian atmosphere and the lander to a sensor error that caused its landing rockets to cut out prematurely.