NASA's Mars Science Laboratory spacecraft, sealed inside its payload fairing atop the United Launch Alliance Atlas V rocket, clears the tower at Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. The mission lifted off at 10:02 a.m. EST November 26, beginning an eight-month interplanetary cruise to Mars.
Photo by NASA/Bill White
Published By : NASA (Goddard & GPL)
Edited By : Engineer Yousuf Ibrahim Khan
Date : 29th November, 2011
NASA began a historic voyage to Mars with the November 26 launch of the Mars Science Laboratory (MSL), which carries a car-sized rover named Curiosity. Liftoff from Cape Canaveral Air Force Station aboard an Atlas V rocket occurred at 10:02 a.m. EST.
Some Key Facts and NASA's Earlier Concerns about MSL:
The MSL mission has four science goals:
1. Determine whether Mars could ever have supported life
2. Study the climate of Mars
3. Study the geology of Mars
4. Plan for a human mission to Mars
To contribute to these goals, MSL has six main scientific objectives:
1. Determine the mineralogical composition of the Martian surface and near-surface geological materials.
2. Attempt to detect chemical building blocks of life (bio-signatures).
3. Interpret the processes that have formed and modified rocks and soils.
4. Assess long-timescale (i.e., 4-billion-year) Martian atmospheric evolution processes.
5. Determine present state, distribution, and cycling of water and carbon dioxide.
6. Characterize the broad spectrum of surface radiation, including galactic radiation, cosmic radiation, solar proton events and secondary neutrons.
Mass of Rover: 1,950 pounds (890 kilograms)
Launch Vehicle:
Atlas V 541 from Cape Canaveral Air Force Station, FL
Arrival at Mars: August 6-20, 2012
The Mars Science Laboratory is designed to enable scientists to determine whether past or present environmental conditions at a selected area on the Red Planet could support microbial life and its preservation in the rock record. Outfitted with six wheels and a sophisticated suite of scientific equipment that includes a large robot arm, a laser, a weather station, and a drill, the Mars Science Laboratory’s jeep-sized rover is named Curiosity. The technology of the rover and its landing system is designed to demonstrate substantial new capabilities and operational techniques that would benefit future NASA missions, from precision landing in a small target zone to extended surface life-times to the transmission of extremely large data volumes back to Earth. Scheduled for launch on an Atlas V rocket, Curiosity will derive its electrical power from a Multi Mission Radioisotope Thermoelectric Generator (MMRTG). Similar to the radioisotope power systems used to safely and successfully power numerous solar system exploration missions from Voyager to Pluto/New Horizons for more than 40 years, the MMRTG will significantly enhance the range and lifetime of the rover. It will also promote greater operability of the rover’s science experiments, which include the first ever plans to drill into Martian rocks for powdered samples to analyze on-site. The MMRTG contains 10.6 pounds (4.8 kilograms) of plutonium dioxide as the source of the steady supply of heat used to produce the onboard electricity and to warm the rover’s systems during the frigid Martian night. As with any NASA mission that relies on a radioisotope power system, the Mars Science Laboratory has undergone a comprehensive multi-agency environmental review, including public meetings and open comment periods, as part of NASA’s compliance with the National Environmental Policy Act. Additionally, the mission will not launch until formal approval is received from the Office of the President. Like previous generations of this type of electrical power generator, the MMRTG is built with several layers of protective material designed to contain its plutonium dioxide fuel in a wide range of potential accidents, verified through impact testing. Each MMRTG carries eight individually shielded general purpose heat source modules (compared to 18 modules in the previous generation). The thickness of the protective graphite material in the center of the modules and between the shells of each module in the MMRTG has been increased by 20 percent over previous modules. Extensive technical analysis of the planned launch of the Mars Science Laboratory, including review of all similar past expendable rocket launches, has been conducted by NASA, the U.S. Department of Energy (which provides the MMRTG), and external experts. This work has determined that the chances of any launch accident are small (3.3 percent), and the chances of an accident of the type that would release plutonium are about ten times smaller. In the event of a launch accident, it is unlikely that any plutonium would be released or that anyone would be exposed to nuclear material. The type of plutonium used in a radioisotope power system is different from the material used in weapons, and cannot explode like a bomb. It is manufactured in a ceramic form that does not become a significant health hazard unless it becomes broken into very fine pieces or vaporized and then inhaled or swallowed. Those people who might be exposed in a Mars Science Laboratory launch accident would receive an average dose of 5-10 millirem, equal to about a week of background radiation. The average American receives 360 millirem of radiation each year from natural sources, such as radon and cosmic rays. NASA, several other federal agencies, the State of Florida and the local governments surrounding Kennedy Space Center are preparing in advance to respond to any launch accident through specific communication procedures, the use of advanced environmental sensors around the launch area, rehearsal of coordinated response to various launch scenarios, and informational briefings to local communities and emergency responders. In the case of a launch accident, related alerts could include precautionary measures such as directions for people to stay indoors for a limited duration.
But Finally it Happened :
Fig : Artist’s concept of Curiosity on Mars
“We are very excited about sending the world’s most advanced scientific laboratory to Mars,” NASA Administrator Charles Bolden said. “MSL will tell us critical things we need to know about Mars, and while it advances science, we’ll be working on the capabilities for a human mission to the Red Planet and to other destinations where we’ve never been.”
The mission will pioneer precision landing technology and a sky-crane touchdown to place Curiosity near the foot of a mountain inside Gale Crater on August 6, 2012. During a nearly two-year prime mission after landing, the rover will investigate whether the region has ever offered conditions favorable for microbial life, including the chemical ingredients for life.
Fig: Full-scale cutaway models of an MMRTG and one of its heat source modules, which produce electricity passively using thermocouples with no moving parts.(The MMRTG is 26 inches [67 centimeters] tall.)
“The launch vehicle has given us a great injection into our trajectory, and we’re on our way to Mars,” said Mars Science Laboratory Project Manager Peter Theisinger of NASA’s Jet Propulsion Laboratory in Pasadena, California. “The spacecraft is in communication, thermally stable, and power positive.”
The Atlas V initially lofted the spacecraft into Earth orbit and then, with a second burst from the vehicle’s upper stage, pushed it out of Earth orbit into a 352-million-mile (567 million kilometers) journey to Mars.
“Our first trajectory correction maneuver will be in about two weeks,” Theisinger said. “We’ll do instrument checkouts in the next several weeks and continue with thorough preparations for the landing on Mars and operations on the surface.”
Curiosity’s ambitious science goals are among the mission’s many differences from earlier Mars rovers. It will use a drill and scoop at the end of its robotic arm to gather soil and powdered samples of rock interiors, then sieve and parcel out these samples into analytical laboratory instruments inside the rover. Curiosity carries 10 science instruments with a total mass 15 times as large as the science- instrument payloads on the Mars rovers Spirit and Opportunity. Some of the tools are the first of their kind on Mars, such as a laser-firing instrument for checking the elemental composition of rocks from a distance and an X-ray diffraction instrument for definitive identification of minerals in powdered samples.
To haul and wield its science payload, Curiosity is twice as long and five times as heavy as Spirit or Opportunity. Because of its 1-ton mass, Curiosity is too heavy to employ airbags to cushion its landing as previous Mars rovers could. Part of the Mars Science Laboratory spacecraft is a rocket-powered descent stage that will lower the rover on tethers as the rocket engines control the speed of descent.
The mission’s landing site offers Curiosity access for driving to layers of the mountain inside Gale Crater. Observations from orbit have identified clay and sulfate minerals in the lower layers, indicating a wet history.
Precision landing maneuvers as the spacecraft flies through the martian atmosphere before opening its parachute make Gale a safe target for the first time. This innovation shrinks the target area to less than one-fourth the size of earlier Mars landing targets. Without it, rough terrain at the edges of Curiosity’s target would make the site unacceptably hazardous.
The innovations for landing a heavier spacecraft with greater precision are steps in technology development for human Mars missions.
In addition, Curiosity carries an instrument for monitoring the natural radiation environment on Mars, important information for designing human Mars missions that protect astronauts’ health.
MSL and Others are on their way :
Fig : This artist's concept shows the MAVEN spacecraft orbiting Mars. NASA/Goddard Space Flight Center
Maybe because it appears as a speck of blood in the sky, the planet Mars was named after the Roman god of war. From the point of view of life as we know it, that’s appropriate. The martian surface is incredibly hostile for life. The Red Planet’s thin atmosphere does little to shield the ground against radiation from the Sun and space. Harsh chemicals, like hydrogen peroxide, permeate the soil. Liquid water, a necessity for life, can’t exist for very long there — any that does not quickly evaporate in the diffuse air will soon freeze out in subzero temperatures common over much of the planet.
It wasn’t always this way. There are signs that in the distant past, billions of years ago, Mars was a much more inviting place. Martian terrain is carved with channels that resemble dry riverbeds. Spacecraft sent to orbit Mars have identified patches of minerals that form only in the presence of liquid water. It appears that in its youth, Mars was a place that could have harbored life with a thicker atmosphere warm enough for rain that formed lakes or even seas.
Two new NASA missions, one that will roam the surface and another that will orbit the planet and dip briefly into its upper atmosphere, will try to discover what transformed Mars. “The ultimate driver for these missions is the question, ‘Did Mars ever have life?’” said Paul Mahaffy of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Did microbial life ever originate on Mars, and what happened to it as the planet changed? Did it just go extinct, or did it go underground where it would be protected from space radiation and temperatures might be warm enough for liquid water?”
The Mars Science Laboratory (MSL) mission features Curiosity, the largest and most advanced rover ever sent to the Red Planet. The Curiosity rover bristles with multiple cameras and instruments, including Goddard’s Sample Analysis at Mars (SAM) instrument suite. By looking for evidence of water, carbon, and other important building blocks of life in the martian soil and atmosphere, SAM will help discover whether Mars ever had the potential to support life. Scheduled to launch in late November or December 2011 (first window of opportunity being November 26), Curiosity will be delivered to Gale Crater, a 96-mile-wide (154 kilometers) crater that contains a record of environmental changes in its sedimentary rock, in August 2012.
The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, scheduled to launch in late 2013, will orbit Mars and is devoted to understanding the Red Planet’s upper atmosphere. It will help determine what caused the martian atmosphere — and water — to be lost to space, making the climate increasingly inhospitable for life.
“Both MAVEN and Curiosity/SAM will determine the history of the martian climate and atmosphere using multiple approaches,” said Bruce Jakosky from the University of Colorado in Boulder. “Measurements of isotope ratios are an approach shared by both missions.”
Isotopes are heavier versions of an element. For example, deuterium is a heavy version of hydrogen. Normally, two atoms of hydrogen join to an oxygen atom to make a water molecule, but sometimes the heavy (and rare) deuterium takes a hydrogen atom’s place.
When water gets lofted into Mars’ upper atmosphere, solar radiation can break it apart into hydrogen (or deuterium) and oxygen. Hydrogen escapes faster because it is lighter than deuterium. Since the lighter version escapes more often, over time the martian atmosphere has less and less hydrogen compared to the amount of deuterium remaining. The martian atmosphere therefore becomes richer and richer in deuterium.
The MAVEN team will measure the amount of deuterium compared to the amount of hydrogen in Mars’ upper atmosphere, which is the planet’s present-day deuterium to hydrogen (D/H) ratio. They will compare it to the ratio Mars had when it was young — the early D/H ratio. The early ratio can be measured from the D/H ratio in ancient martian minerals and estimated from observations of the D/H ratio in comets and asteroids, which are believed to be pristine “fossil” remnants of our solar system’s formation.
Comparing the present and early D/H ratios will allow the team to calculate how much hydrogen — and, therefore, water — has been lost over Mars’ lifetime. MAVEN will also determine how much martian atmosphere has been lost over time by measuring the isotope ratios of other elements in the high atmosphere, such as nitrogen, oxygen, carbon, and noble gases like argon.
MAVEN is expected to reach Mars in 2014. By then, SAM on board the Curiosity rover will have made similar measurements from Gale Crater, which will help guide the interpretation of MAVEN’s upper atmosphere measurements.
Measuring isotopes in the atmosphere will reveal its present state. To find out what the martian atmosphere was like in the past, scientists will use what they discover with MAVEN about the various ways the atmosphere is being removed. With that data, they will build computer simulations to estimate the condition of the Red Planet’s atmosphere billions of years ago.
Scientists estimate Gale Crater may have formed more than three billion years ago. Curiosity will grind up Gale Crater minerals and deliver them to SAM so the isotope ratios can be measured, giving a glimpse of the martian atmosphere from long ago, perhaps when it could have supported life. “SAM’s inputs from the surface of past martian history will help the MAVEN team work backwards to discover how the martian atmosphere evolved,” said Joseph Grebowsky from NASA’s Goddard Space Flight Center.
“For example, MAVEN will focus primarily on how solar activity erodes the martian atmosphere,” said Mahaffy. Things like the solar wind, a tenuous stream of electrically conducting gas blown from the surface of the Sun, explosions in the Sun’s atmosphere called solar flares, and eruptions of solar material called coronal mass ejections can all strip away the upper atmosphere of Mars in various ways. “If we figure out how much atmosphere is removed by changes in solar activity, we can extrapolate back to estimate what the isotope ratios should have been billions of years ago. However, if the measurements of the ancient ratios from SAM don’t match up, this suggests that we may have to look at other ways the atmosphere could have been lost, such as giant impacts from asteroids,” said Mahaffy. Some scientists believe giant impacts could have blasted significant amounts of the martian atmosphere into space.
Also, Curiosity will carry a weather station, which will help the MAVEN team understand how changes in the upper atmosphere are related to changes at the surface. “For example, if the rover detects a dust storm, it may have an effect higher up because of the winds and the gravity waves — the bobbing up and down of a parcel of air — it sets up,” said Grebowsky.
“Curiosity will focus on geology and minerals to determine if the environment on Mars in the distant past had the potential to support life,” said Mahaffy. “It will be digging in the dirt trying to understand the habitability issue in a place where water may have flowed, where there could have been a lake. Habitability is also the basic theme of MAVEN — it will be trying to understand from the top down how the atmosphere evolved over time and how it was lost, which ties back to how clement it was early on.”
For further information about these missions, contact:
David Lavery
Science Mission Directorate
NASA Headquarters
Washington, DC 20546
(202) 358-4684
david.lavery@hq.nasa.gov
