2001 Mars Odyssey

Incorporating lessons learned from past and ongoing Mars mission successes and setbacks, NASA's revamped campaign to unravel the secrets of the Red Planet moves from an era of global mapping and limited surface exploration to a much more comprehensive approach in which next-generation reconnaissance from orbit and from the surface will pave the way for multiple sample returns.

Over the next two decades, NASA's Mars Exploration Program will build upon previous scientific discoveries to establish a sustained observational presence both around and on the surface of Mars. This will be achieved from the perspective of orbital reconnaissance and telecommunication, surface-based mobile laboratories, sub-surface access and, ultimately, by means of robotic sample return missions. With international cooperation, the long-term program will maintain a science-driven, technology-enabled focus, while balancing risks against sound management principles and with attention to available resources. The strategy of the Mars Exploration Program will attempt to uncover profound new insights into Mars past environments, the history of its rocks and interior, the many roles and abundances of water and, quite possibly, evidence of past and present life. The following are the most recently completed, ongoing and near-term future Mars missions of exploration in the NASA program:

Mars Pathfinder (December 1996 - March 1998): The first completed mission in NASA's Discovery Program of low-cost, rapidly developed planetary missions with highly focused scientific goals, Mars Pathfinder far exceeded its expectations and outlived its primary design life. This lan-der, which released its Sojourner rover at the Martian surface, returned 2.3 billion bits of informa-tion, including more than 17,000 images, as well as more than 15 chemical analyses of rocks and soil and extensive data on winds and other types of weather. Investigations carried out by instru-ments on both the lander and the rover suggest that, in its past, Mars was warm and wet, and had liquid water on its surface and a thicker atmosphere. Engineers believed that, in October 1997, a depletion of the spacecraft's battery and a drop in the spacecraft's operating temperature were to blame for the loss of communications with Pathfinder. Attempts to re-establish communications with the vehicle ceased in March 1998, well beyond the mission's expected 30-day lifetime.

Mars Global Surveyor (November 1996 - January 2001 primary mapping mission): Orbiting the red planet 8,985 times so far, NASA's Mars Global Surveyor has collected more information than any other previous Mars mission and keeps on going into its extended mission. Sending back more than 65,000 images, 583 million topographic laser-altimeter shots and 103 million spectral measurements, Global Surveyor's comprehensive observations have proven invaluable to under-standing the seasonal changes on Mars. Some of the mission's most significant findings include: possible evidence for recent liquid water at the Martian surface; evidence for layering of rocks that point to widespread ponding or lakes in the planet's early history; topographic evidence for a south pole-to-north pole slope that controlled the transport of water and sediments; identification of the mineral hematite, indicating a past surface-hydrothermal environment; and extensive evidence for the role of dust in reshaping the recent Martian environment. Global Surveyor will continue gather-ing data in an extended mission approved until 2002.

Mars Exploration Rovers (2003): Identical twin rovers, able to travel almost as far in one Martian day as Sojourner did over its entire lifetime, will land at two separate sites and set out to determine the history of climate and water on the planet where conditions may once have been very favorable for life. By means of sophisticated sets of instruments and access tools, the twin rovers will evaluate the composition, texture and morphology of rocks and soils at a broad variety of scales, extending from those accessible to the human eye to microscopic levels. The rover sci-ence team will select targets of interest such as rocks and soils on the basis of images and infrared spectra sent back to Earth. Two different Martian landing sites will be chosen on the basis of an intensive examination of information collected by the Mars Global Surveyor and Mars Odyssey orbiters, as well as other missions.

Mars Reconnaissance Orbiter (2005): This scientific orbiter will attempt to bridge the gap between surface observations and measurements taken from orbit. It will focus on analyzing the Martian surface at new scales in an effort to follow the tantalizing hints of water from the Mars Global Surveyor images. For example, the Mars Reconnaissance Orbiter will measure thousands of Martian landscapes at 20- to 30-centimeter (8- to 12-inch) resolution, which is adequate to observe rocks the size of beach balls. In addition, maps of minerals diagnostic of the role of liquid water in their formation will be produced at unprecedented scales for thousands of potential future landing sites. Finally, a specialized, high-resolution sounding radar will probe the upper hundreds of meters (or yards) of the Martian sub-surface in search of clues of frozen pockets of water or other unique layers. Finally, the Mars Reconnaissance Orbiter will finish the job of characterizing the transport processes in the present-day Martian atmosphere, including the planet's annual cli-mate cycles, using a unique infrared sounding instrument, originally carried to Mars on the ill-fated Mars Observer, and then again on Mars Climate Orbiter.

Smart Lander (2007): NASA has proposed to develop and launch a next-generation "mobile surface laboratory" with potentially long-range roving capabilities (greater than 10 kilometers (about 6 miles)) and more than a year of surface operational lifetime as a pivotal step toward a future Mars sample return mission. By providing a major leap forward in surface measurement capabili-ties and surface access, this mission will also demonstrate the technology needed for accurate landing and surface hazard avoidance in order to allow access to potentially compelling, but diffi-cult to reach, landing sites. Its suite of scientific instruments could include new devices that will sample and probe the Martian subsurface in search of organic materials.

Scout Mission (2007): NASA has also proposed to create a new line of small "scout" missions that would be competitively selected from proposals submitted by the broader scientific and aero-space community. Exciting new vistas could be opened by means of this innovative approach, either through observations made from airborne vehicles, networks of small surface landers, or from highly focused orbital laboratories. NASA aims to compete these scout missions as often as possible, and potentially every four years, depending on resource availability.

Mars Sample Return (earliest launch possibility late 2011): NASA is studying additional scien-tific orbiters, rovers and landers, as well as approaches for returning the most promising samples of Martian materials (rocks, soils, ices and atmospheric gases/dust) back to Earth. While current schedules call for the first of several sample return missions to be launched in 2014 with a second mission in 2016, options that could move the date sooner to 2011 are presently under detailed examination. Technology development is underway for advanced capabilities including a new gen-eration of miniaturized surface instruments such as mass spectrometers and electron microscopes, as well as deep drilling to 20 meters (about 20 yards) or more.