The following are some fast facts about NASA's recent mission to Mars:

•  The entire mission has a price tag of $800 million.

•  The Mars Exploration Rovers will crawl up to 330 feet per day across two pre-selected landing sites, examining rocks and soil and taking photos.

•  The rovers are solar-powered.

•  Software installed on the rovers -- combined with stereoscopic vision -- will allow them to autonomously navigate around obstacles while out of contact with NASA ground controllers.

•  Data will be will transmited back to Earth twice each afternoon through radio links with the Mars Global Surveyor and Mars Odyssey spacecraft currently in orbit around Mars.

Spirit Mission

• Launch: June 10, 2003, from Cape Canaveral, Fla.

• Mars landing: 2:20 p.m. on Jan. 4, 2004 (local Mars time); Signal received on Earth 8:35 p.m. PST on Jan. 3, 2004)

• Landing Site: Gusev Crater (which is bigger than Connecticut)

• Total Distance Traveled From Earth to Mars: approximately 303 million miles

• Length of Primary Mission: 90 Mars days, or "sols" (approx. 92 Earth days)

Opportunity Mission

• Launch: July 7, 2003, from Cape Canaveral, Fla.

• Expected Mars Landing: About 1:15 p.m. on Jan. 25, 2004 (local Mars time)

• Landing Site: Meridiani Planum (mineral deposits suggest possible past existence of water)

• Total Distance Traveled from Earth to Mars: approximately 283 million miles

• Length of Primary Mission: 90 Mars days, or "sols" (approx. 92 Earth days)