Opportunity Mars Rover Mission Information

mars landscape
A view of Marathon Valley on Mars as seen by the Mars Opportunity Rover in June 2016. NASA

The Opportunity rover (officially called the Mars Exploration Rover B) is (as of mid-2016) the longest-running rover on the Red Planet. Among its many accomplishments, it has found the strongest evidence yet that liquid water once existed on the surface of Mars. Scientists suspect the rover's Meridiani Planum landing site was once the shoreline of a salty sea on Mars, during a time when Mars was wetter and warmer than it is now.

Opportunity has traveled across more than 41 km (26 miles) of Martian landscape, cataloging rocks, minerals, and the thin Martian atmosphere as it goes. Its instruments dig into the surface, scrape at the rocks, and if it gets a chance, they may be the first to ever sample Martian water as it makes its way to the surface in a nearby crater wall. Opportunity is still going strong, more than 4,412 days since it settled onto the surface of Mars. It was joined on Mars by the Curiosity rover in 2012, and that mission is also still going strong.

An Up-close Look at Opportunity

Opportunity consists of a box-like chassis mounted on six wheels. The chassis contains the warm electronics box (WEB). On top of the WEB is the triangular rover equipment deck, on which is mounted the Pancam mast assembly, high gain, low gain, and UHF antennas, and a camera calibration target. There are two solar arrays to power the rover.

 

Opportunity carries science and navigation instruments. The panoramic camera (Pancam) and navigation cameras are mounted on top of the Pancam mast assembly, at a height of about 1.4 meters from the base of the wheels. The mast also acts as a periscope for the Miniature Thermal Emission Spectrometer (Mini-TES).

Attached to the end of the instrument deployment device are the Alpha Particle X-ray Spectrometer (APXS), Mossbauer Spectrometer (MB), Microscopic Imager (MI), and Rock Abrasion Tool (RAT). A magnet array is attached to the front of the equipment deck.

Two hazard avoidance cameras are mounted on the front of the rover and two on the rear. The group of science instruments (Pancam, Mini-TES, APXS, MB, MI, and RAT) is known as the Athena science package.

Opportunity's Trip to Mars

Opportunity was launched on a heavy Delta II 7925H on 8 July 2003 at 03:18:15 UT (July 7, 11:18:15 p.m. EDT). After insertion into a circular Earth parking orbit, the spacecraft third stage reignited and put the craft on a trajectory to Mars, after which the aeroshell, lander, and rover separated from the third stage. The cruise phase to Mars ended on 11 December 2003, 45 days before Mars entry. The approach phase lasted from this date until martian atmospheric entry on 25 January 2004. On entry the lander and components had a mass of 827 kg and were travelling at 19,300 km/hr (11,992 mph). The aeroshell decelerated the lander in the upper martian atmosphere for about four minutes to a velocity of 1,600 km/hr (about 994 mph) followed by deployment of a parachute.

The parachute slowed the spacecraft to about 300 km/hr (186 mph). A series of tones transmitted by the spacecraft during entry and after landing indicated the successful completion of each phase. Just prior to impact, at an altitude of about 100 m (300 feet), retrorockets slowed the descent and airbags inflated to cushion the impact. The craft hit at roughly 50 km/hr (31 mph) and bounced and rolled along the surface, stopping in a small crater. The airbags deflated and retracted, the petals opened, and the rover deployed its solar arrays. Eventually, it rolled off the base and began its mission.

The landing took place at 5:05 UT (Earth received time), 12:05 a.m. EST or approximately 1:15 p.m. local time, about two and a half hours before Earth set at Terra Meridiani. On Mars, it was the latter half of southern summer.

Terra Meridiani is also known as the "Hematite Site" because it displays evidence of coarse-grained hematite, an iron-rich mineral which typically forms in water. It was one of the smoothest and therefore safest areas for a landing.

An egress phase took place over the first four days, involving deployment of the Pancam mast and high gain antenna, rover stand up, imaging and calibration, selection of proper egress path, and finally driving of the rover off the lander deck onto the martian surface.

Opportunity was originally scheduled for 90 days of surface operations. It has lasted far longer than that, performing its work for 12 years. Its tasks involve driving the rover, doing imaging, and deploying science instruments to search for signs of water and to understand Martian rocks. It has had its mission extended several times and continues to roll along the dusty surface of Mars in apparently pretty good shape. It is making contributions to our understanding of Mars in the past as well as the present. 

Edited and updated by Carolyn Collins Petersen.