STS-135 (ISS assembly flight ULF7) is the final mission of the American Space Shuttle. It uses hardware originally processed for the STS-335 contingency mission, as the Launch On Need (LON) rescue mission designated to support STS-134 was not ultimately needed. The mission launched on 8 July and was scheduled to land on 20 July 2011 but the mission was extended to 21 July 2011. The four person STS-135 crew was the smallest of any shuttle mission since April 1983's STS-6. The mission's primary cargo was the Multi-Purpose Logistics Module (MPLM) Raffaello and a Lightweight Multi-Purpose Carrier (LMC). The flight of MPLM Raffaello on Space Shuttle Atlantis also marked the first and only time that Atlantis hauled an MPLM to space.
Although the mission was authorized, it initially had no appropriation in the NASA budget, raising questions about whether the mission would fly. On 20 January 2011, program managers changed STS-335 to STS-135 on the flight manifest. This allowed for training and other mission specific preparations. On 13 February 2011, program managers told their workforce that STS-135 would fly "regardless" of the funding situation via a continuing resolution. Until this point, there had been no official references to the STS-135 mission in NASA official documentation for the general public.
During an address at the Marshall Space Flight Center on 16 November 2010, NASA administrator Charles Bolden said that the agency needed to fly STS-135 to the station in 2011, due to likely delays in the development of commercial rockets and spacecraft designed to transport cargo to the ISS. "We are hoping to fly a third shuttle mission (in addition to STS-133 and STS-134) in June 2011, what everybody calls the launch-on-need mission... and that's really needed to [buy down] the risk for the development time for commercial cargo," Bolden said.
The mission was included in NASA's 2011 authorization, signed into law on 11 October 2010, but funding remained dependent on a subsequent appropriation bill. United Space Alliance signed a contract extension for this mission, along with STS-134; the contract contained six one-month options with NASA in order to support continuing operations.
The US government budget approved in mid-April 2011 called for $5.5 billion for NASA's space operations division, including the space shuttle and space station programs. According to NASA, the budget running through 30 September 2011 ended all concerns about funding the STS-135 mission.
Mars Science Laboratory will study Mars' habitability
To find out, the rover will carry the biggest, most advanced suite of instruments for scientific studies ever sent to the martian surface. The rover will analyze dozens of samples scooped from the soil and drilled from rocks. The record of the planet's climate and geology is essentially "written in the rocks and soil" -- in their formation, structure, and chemical composition. The rover's onboard laboratory will study rocks, soils, and the local geologic setting in order to detect chemical building blocks of life (e.g., forms of carbon) on Mars and will assess what the martian environment was like in the past.
Mars Science Laboratory relies on innovative technologies
Mars Science Laboratory will rely on new technological innovations, especially for landing. The spacecraft will descend on a parachute and then, during the final seconds prior to landing, lower the upright rover on a tether to the surface, much like a sky crane. Once on the surface, the rover will be able to roll over obstacles up to 75 centimeters (29 inches) high and travel up to 90 meters (295 feet) per hour. On average, the rover is expected to travel about 30 meters (98 feet) per hour, based on power levels, slippage, steepness of the terrain, visibility, and other variables.
The rover will carry a radioisotope power system that generates electricity from the heat of plutonium's radioactive decay. This power source gives the mission an operating lifespan on Mars' surface of a full martian year (687 Earth days) or more, while also providing significantly greater mobility and operational flexibility, enhanced science payload capability, and exploration of a much larger range of latitudes and altitudes than was possible on previous missions to Mars.
Arriving at Mars in 2012, Mars Science Laboratory will serve as an entrée to the next decade of Mars exploration. It represents a huge step in Mars surface science and exploration capability because it will:
demonstrate the ability to land a very large, heavy rover to the surface of Mars (which could be used for a future Mars Sample Return mission that would collect rocks and soils and send them back to Earth for laboratory analysis)
demonstrate the ability to land more precisely in a 20-kilometer (12.4-mile) landing circle
demonstrate long-range mobility on the surface of the red planet (5-20 kilometers or about 3 to 12 miles) for the collection of more diverse samples and studies.