Life on Mars? Curiosity landing on Red Planet scheduled for August 6, 2012

Curiosity rover will attempt safe landing on Gale Crater, Mars in just three days. At 10:31 p.m. August 5 PDT (1:31 a.m. August 6 EDT, 05:31 August 6 UTC Earth time – 3 pm Mars time) NASA’s Mars Science Laboratory mission will attempt to deliver the nearly 1-ton, car-size robotic roving laboratory to the surface of Mars.

Curiosity rover landing will mark the start of a two-year prime mission to investigate whether one of the most intriguing places on Mars ever has offered an environment favorable for microbial life.

“Curiosity is a bold step forward in learning about our neighboring planet, but this mission does not stand alone. It is part of a sustained, coordinated program of Mars exploration,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. “This mission transitions the program’s science emphasis from the planet’s water history to its potential for past or present life.”

NASA will be using the Mars Odyssey orbiter, in service since 2001, as a relay for rapidly confirming the landing to Curiosity’s flight team and the rest of the world. Earth will be below the Mars horizon from Curiosity’s perspective, so the new rover will not be in direct radio contact with Earth. Two newer orbiters also will be recording Curiosity’s transmissions, but that data will not be available on Earth until hours later.

Mission overview

Mars Science Laboratory mission will study whether the Gale Crater area of Mars has evidence of past and present habitable environments.

These studies will be part of a broader examination of past and present  processes in the Martian atmosphere and on its surface.  The research will use 10 instrument-based science investigations. The mission’s rover, Curiosity, carries the  instruments for these investigations and will support their use by providing overland mobility, sample-acquisition capabilities, power and communications. The primary mission will last one Mars year (98 weeks).

The payload includes mast-mounted instruments to survey the surroundings and assess potential sampling targets from a distance; instruments on Curiosity’s robotic arm for close-up inspections; laboratory instruments inside the rover for analysis of samples from rocks, soils and atmosphere; and instruments to monitor the environment around the rover. In addition to the science payload, engineering sensors on the heat shield will gather information about Mars’ atmosphere and the spacecraft’s performance during its descent through the atmosphere.

To make best use of the rover’s science capabilities, a diverse international team of scientists and engineers will make daily decisions about the rover’s activities for the following day. Even if all the rover’s technology performs flawlessly, some types of evidence the mission will seek about past environments may not have persisted in the rock record. While the possibility that life might have existed on Mars provokes great interest, a finding that conditions did not favor life would also pay off with valuable insight about differences and similarities between early Mars and early Earth.

Habitability

The mission will assess whether the area Curiosity explores has ever been a potential habitat for Martian life. Whether life has existed on Mars is an open question that this mission, by itself, is not designed to answer.

Curiosity does not carry experiments to detect active processes that would signify present-day biological metabolism, nor does it have the ability to image microorganisms or their fossil equivalents. However, if this mission finds that the field site in Gale Crater has had conditions favorable for habitability and for preserving evidence about life, those findings can shape future missions that would bring samples back to Earth for life-detection tests or for missions that carry advanced life-detection experiments to Mars.

In this sense, the Mars Science Laboratory is the prospecting stage in a step-by-step program of exploration, reconnaissance, prospecting and mining evidence for a definitive answer about whether life has existed on Mars. NASA’s Astrobiology Program has aided in development of the Mars Science Laboratory science payload and in studies of extreme habitats on Earth that can help in understanding possible habitats on Mars.

Three conditions considered crucial for habitability are liquid water, other chemical ingredients utilized by life and a source of energy. The Mars Science Laboratory mission advances the “follow the water” strategy of NASA Mars exploration since the mid-1990s to a strategy of determining the best settings for seeking an answer to whether Mars ever supported life.

Every environment on Earth where there is liquid water sustains microbial life. For most of Earth’s history, the only life forms on this planet were microorganisms, or microbes. Microbes still make up most of the living matter on Earth. Scientists who specialize in the search for life on other worlds expect that any life on Mars, if it has existed at all, has been microbial.

Curiosity will land in a region where this key item on the checklist of life’s requirements has already been determined: It was wet. Observations from Mars orbit during five years of assessing candidate landing sites have made these areas some of the most intensely studied places on Mars. Researchers have used NASA’s Mars Reconnaissance Orbiter to map the area’s mineralogy, finding exposures of clay minerals. Clays, other phyllosilicates and sulfates form under conditions with adequate liquid water in a life-supporting, medium range between very acidic and very alkaline.

Curiosity will inventory other basic ingredients for life, seek additional evidence about water and investigate how conditions in the area have changed over time. The wet environment in which the clay minerals formed is long gone, probably occurring more than 3 billion years ago. Examining the geological context for those minerals, such as the minerals in younger rock layers, could advance understanding of habitat change to drier  conditions. The rover can also check for traces of water  still bound into the mineral structure of rocks at and near the surface.

Carbon-containing compounds called organic molecules are an important class of ingredients for life that Curiosity can detect and inventory. This capability adds a trailblazing “follow the carbon” aspect to the Mars Science Laboratory, as part of the sequel to the “follow the water” theme. Organic molecules contain one or more carbon atoms bound to hydrogen and, in many cases, additional elements. They can exist without life, but life as we know it cannot exist without them, so their presence would be an important plus for habitability.

If Curiosity detects complex organics that are important to life on Earth, such as amino acids, these might be of biological origin, but also could come from non-biological sources, such as carbonaceous meteorites delivered to the surface of the planet.

Curiosity will also check for other chemical elements important for life, such as nitrogen, phosphorus, sulfur and oxygen.

The rover will definitively identify minerals, which provide a lasting record of the temperatures, pressures and chemistry present when the minerals were formed or altered. Researchers will add that information to observations about geological context, such as the patterns and processes of sedimentary rock accumulation, to chart a chronology of how the area’s environments have changed over time. Energy for life on Mars could come from sunlight, heat or mixtures of chemicals (food) with an energy gradient that could be exploited by biological metabolism.

The information Curiosity collects about minerals and about the area’s modern environment will be analyzed for clues about possible past and present energy sources for life.

Curiosity will measure the ratios of different isotopes of several elements. Isotopes are variants of the same element with different atomic weights. Ratios such as the proportion of carbon-13 to carbon-12 can provide insight into planetary processes. For example, Mars once had a much denser atmosphere than it does today, and if the loss occurred at the top of the atmosphere, that process would favor increased concentration of heavier isotopes in the retained, modern atmosphere. Such processes can be relevant to habitability and biology.

Curiosity will assess isotopic ratios in methane if that gas is in the air around the rover. Methane is an organic molecule, and its carbon isotope ratio can be very distinctive. Observations from orbit and from Earth indicate traces of it may be present in Mars’ atmosphere. Isotopic ratios could hold clues about whether methane is being produced by microbes or by a non-biological process.

The mission has four primary science objectives to meet NASA’s overall habitability assessment goal:

• Assess the biological potential of at least one target environment by determining the nature and inventory of organic carbon compounds, searching for the chemical building blocks of life and identifying features that may record the actions of biologically relevant processes.
• Characterize the geology of the rover’s field site at all appropriate spatial scales by investigating the chemical, isotopic and mineralogical composition of surface and near-surface materials and interpreting the processes that have formed rocks and soils.
• Investigate planetary processes of relevance to past habitability (including the role of water) by assessing the long-time-scale atmospheric evolution and determining the present state, distribution and cycling of water and carbon dioxide.
• Characterize the broad spectrum of surface radiation, including galactic cosmic radiation, solar proton events and secondary neutrons.

More about mission and program

Launch

• Launch Time and Place: Nov. 26, 2011, 10:02 a.m. EST, from Launch Complex 41, Cape Canaveral Air Force Station, Fla.
• Launch Vehicle: Atlas V 541 provided by United Launch Alliance
• Earth–Mars distance at launch: 127 million miles  (204 million kilometers)

Program

• Cost: $2.5 billion, including $1.8 billlion for spacecraft development and science investigations and additional amounts for launch and operations.

Mission

• Time of Mars landing: 10:31 p.m. Aug. 5 PDT (1:31 a.m. Aug. 6 EDT, 05:31 Aug. 6 Universal Time) plus or minus a minute. This is Earth-received time, which includes one-way light time for radio signal to reach Earth from Mars. The landing will be at about 3 p.m. local time at the Mars landing site.
• Landing site: 4.6 degrees south latitude, 137.4 degrees east longitude, near base of Mount Sharp inside Gale Crater
• Earth–Mars distance on landing day: 154 million miles (248 million kilometers)
• One-way radio transit time, Mars to Earth, on landing day: 13.8 minutes
• Total distance of travel, Earth to Mars: About 352 million miles (567 million kilometers)
• Primary mission: One Martian year (98 weeks)
• Expected near-surface atmospheric temperatures at landing site during primary mission: minus 130 F to 32 F (minus 90 C to zero C)

Mars landing sky show

On the same night Curiosity lands on Mars, a “Martian Triangle” will appear in sunset skies of Earth. The first-magnitude apparition on August 5th gives space fans something to do while they wait for news from the Red Planet.

Learn more about mission: www.nasa.gov