Mars Exploration Program Research Articles

On Water Detection in the Martian Subsurface Using Sounding Radar

Several radar experiments are planned to map the martian subsurface down to several kilometers, searching for subsurface liquid water reservoirs, using different concepts and techniques, all based on the penetration property of radio frequency waves in arid soils. The penetration depth of low-frequency radar is mainly related to the electromagnetic properties of the investigated medium. Thus a good knowledge of the martian subsurface dielectric profile along the first few kilometers is necessary for future water identification and data interpretation. In this work we have investigated the electrical and magnetic properties of the martian surface and subsurface, using terrestrial laboratory analogues in the frequency range 1–500 MHz, covering the frequency domain of the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) experiment on board the Mars Express mission (ESA–2003), the NetLander ground-penetrating radar (GPR) (CNES–2007), and future sounding radar that may be updated to the Mars exploration program in the “follow the water” strategy. In our approach, we constructed experimentally the most common dielectric profile representative of the martian subsurface by measuring the electric permittivity and magnetic permeability of well defined mixtures of basaltic, volcanic, and sedimentary materials that have been reported for Mars. We also considered iron oxides (hematite and maghemite) and evaporites that may be present, such as gypsum, and their mixtures with representative amounts of the martian geological context under the most common petrophysical and geophysical conditions, along the subsurface profile. This led to synthetic representative samples of the martian subsurface materials under adequate conditions of porosity and temperature that should exist in the first 2.5 km of the upper crust. Dielectric measurements show that the first layers of the martian subsurface (a few hundred meters), which are mainly composed of volcanic iron-rich materials, could dramatically decrease the radar penetration depth initially foreseen, thus limiting deep subsurface exploration. We also investigated the constraints on subsurface water detectability in a radar lossy medium and its dielectric identification among surrounding geological materials.

In Brief

Eugene L. Tattini will become the Jet Propulsion Laboratory’s deputy director in August, succeeding Larry N. Dumas, who will be retiring after nine years in that position. Tattini, who joined JPL this month to spend several weeks in orientation before taking his new post, was commander of the Space and Missile Systems Center at Los Angeles Air Force Base. He retired from the Air Force after nearly 36 years of service. Orlando Figueroa became the acting director of NASA’s Mars exploration program, Office of Space Science, at NASA headquarters in Washington, DC, this past May. Formerly the deputy chief engineer for systems engineering at NASA headquarters, Figueroa replaced G. Scott Hubbard, who is now the deputy center director for research at NASA’s Ames Research Center at Moffett Field, California.At a ceremony in May in Canberra, the Australian Academy of Sciences awarded Bruce Hobbs the Jaeger Medal for “investigations of a high order into the solid earth or oceans of Australia,” according to the citation. Hobbs is deputy chief executive of the minerals and energy research sector of CSIRO, the Commonwealth Scientific and Industrial Research Organization, in Perth, Australia. Last month, the Ho-Am Foundation, located in South Korea, presented awards to winners in five categories at a ceremony in Seoul. Of those winners, two are doing physics-related work. Edward C. Lim, Goodyear Professor of Chemistry at the University of Akron, received the 2001 Ho-Am Prize for Science in recognition of “his distinguished contribution to and pioneering research in laser spectroscopy and photophysics of organic molecules, which resulted in his discovery of the proximity effect governing the rate of electronic relaxation in photoexcited organics,” according to the foundation. Dong Nyung Lee, a professor of materials science and engineering at Seoul National University, won the 2001 Ho-Am Prize for Engineering, which acknowledged “his distinguished contribution to the field of metallic materials and his discovery of the strain energy release maximization theory explaining the transformation of fabrication textures into recrystallization textures.” Each honoree received a diploma, gold medal, and 100 million won (about $77‥000). Fusion researcher and plasma diagnostics specialist Kenneth Young received the US Department of Energy’s Distinguished Associate Award in April at a dinner in Princeton, New Jersey. The occasion was his retirement that same month as head of international collaborations at the Princeton Plasma Physics Laboratory. The DOE citation acknowledged, in part, that his “dedicated efforts have had a major impact on the diagnostics systems that bind theory and experiment together in advancing fusion.” Young had joined the lab in 1974.© 2001 American Institute of Physics.

Italian participation in the Mars exploration program

Recently agreements have been signed between the Italian Space Agency (ASI) and ESA and NASA for the exploration of Mars. These agreements initiate the participation of the Italian scientific community as well as the Italian industrial community in the international program to explore Mars. ASI and NASA have agreed to co-operate in a long-term systematic program of robotic exploration of Mars sustained by a series of missions to Mars in support of their respective strategic goals. The Mars Surveyor Program is a sustained series of missions to Mars, each of which will provide important focused scientific results. ASI is expecting to participate in the future missions with the provision of two sub-systems: a subsurface drill and a scientific package. The drill will be capable of drilling and collecting several samples and delivering them to instruments located within a scientific package fixed on a landed platform. ASI is also providing scientific instruments placed on a scientific package (IPSE) fixed with on the lander platform. The goals of the investigations are to study physical and mineralogical properties of bulk soil and dust (atmospheric and surface) as well as geochemical, structural, radiation and geophysical properties of subsurface materials to a depth of 0.5 meters.

Scientific objectives of the DYNAMO mission

DYNAMO is a small Mars orbiter planned to be launched in 2005 or 2007, in the frame of the NASA/ CNES Mars exploration program. It is aimed at improving gravity and magnetic field resolution, in order to better understand the magnetic, geologic and thermal history of Mars, and at characterizing current atmospheric escape, which is still poorly constrained. These objectives are achieved by using a low periapsis orbit, similar to the one used by the Mars Global Surveyor spacecraft during its aerobraking phases. The proposed periapsis altitude for DYNAMO of 120–130 km, coupled with the global distribution of periapses to be obtained during one Martian year of operation, through about 5000 low passes, will produce a magnetic/gravity field data set with approximately five times the spatial resolution of MGS. Additional data on the internal structure will be obtained by mapping the electric conductivity. Low periapsis provides a unique opportunity to investigate the chemical and dynamical properties of the deep ionosphere, thermosphere, and the interaction between the atmosphere and the solar wind, therefore atmospheric escape, which may have played a crucial role in removing atmosphere and water from the planet.

Unacceptable Renewals

Unacceptable Renewals

Fountains of Youth

The search for geologic features indicative of past or present water is central to Mars exploration programs. As Tanaka explains in his Perspective, such features have tended to be associated with very old (> 1 billion years) regions. However, a study by Malin and Edgett indicates that the youngest geologic features on Mars show signs of fluid discharge and runoff. If the results hold up, then some very unusual event must have occurred in the recent past on Mars.

Exploration geophysics on Mars: Lessons from magnetics

NASA's exploration of the solar system has often included magnetometers (e.g., Voyager, Mariner 10) to provide insight into the deep interior of the planets. Recently, however, a pair of magnetometers aboard the orbiting Mars Global Surveyor (MGS) satellite detected an unmistakable magnetic signature from the Martian crust. The magnetic signatures record tectonism from Mars' infancy—four billion years ago. The maximum magnetic field measured by MGS from the Martian crust is 20 times larger than that measured by earth-orbiting satellites at a comparable altitude. As on earth, interpretation of these magnetic fields aids in identification of provinces of interest for mineral exploration. With payload costs hovering around US$1 million/kilogram, it will become increasingly desirable to attempt to exploit local resources rather than relying on terrestrial resources for Martian exploration. The United States, Japan, and the European Space Agency all have active Mars exploration programs. France will join this ...

Low cost mission to Phobos and Deimos

The motivation to continue the exploration of Phobos and Deimos is strongly supported by the need to understand the basic scientific nature of the Martian moons both as representatives of the family of small bodies in the Solar System, and as components of the planet Mars system (see ref. 1–13). There are a number of key unresolved scientific problems related to the Mars, Phobos, and Deimos (MPD) system. The main one being the problem of origin and evolution of the MPD system, solution of which requires knowledge of the chemical composition of Martian moons, impact history and surface morphology, internal structure etc. This investigation fits into the Mars Exploration Program, as the moons are part of the entire Mars system. We propose a low cost mission to Phobos and Deimos using a modest electric thruster (~ 350W) for orbital evolution within the MPD system. Such engine can empower a spacecraft (with dry mass of 100–120 kg) to fly from the Mars capture orbit to Deimos and Phobos orbits. The mass of science payload between 15 to 25 kg would provide for Ihe basic instruments relevant for the close encounter scenario. The different options studied for the initial insertion into a capture orbit around Mars include piggybacking and the use of decommissioned ICBM's.

Unacceptably New

Unacceptably New

Autonomous Navigation and the Sojourner Microrover

The Mars exploration program has as an overarching theme the search for and understanding of life, climate and resources on Mars. The ability to move about the surface of Mars is key to making measurements and the gathering of the data which address this theme.

“Mars on $300K a day”: The Mars exploration program: Second IAA International Conference on Low-Cost Planetary Missions

The Mars Exploration Program is pioneering a series of “better, faster, cheaper” missions to Mars over at least the next 10 years, and possibly well into the 21st century. The overall cost of the program is somewhat over $100M per year, including launch vehicles and operations, for two launches every 26 months. (This works out to about $300K per day.) A programmatic strategy has been developed involving selection of a science theme for the program, a long-term industrial partnership for spacecraft development, continuous infusion of new technology, and integration of the individual projects into an overall program so that synergy between projects can be maximized. A number of process improvements have been made in procurement, concurrent engineering, rapid prototyping, and integrated payload selection, among others.

International strategy for the exploration of Mars

Of the different objects within the Solar System, Mars has long had a special appeal, because of its resemblance to the Earth, the variety of science issues it poses, the possibility that life might have started there, and its potential for eventual human exploration. As a result all space agencies involved in planetary exploration are interested in participating in some way in Mars' exploration. Yet in this era of fiscal constraint, individual agencies and nations are finding it difficult to mount their own independent Mars exploration programs. One way of sustaining a healthy exploration program in this environment is through international cooperation. The International Mars Exploration Working Group has examined the science goals of Mars exploration, the currently approved missions of different agencies, the constraints and desires of those agencies for participating in future Mars exploration, and formulated a tentative plan for Mars exploration for the next decade. The plan includes multiple missions to Mars at every launch opportunity, and culminates in emplacement of a broadly international network of stations at the 2003 launch opportunity. The plan is tentative and fragile. While efforts were made to make the plan realistic, and consistent with funding expectations for the next several years, it will inevitably require change as some expectations are realized and others are not. At the time of writing, different elements of the plan are in different stages of implementation. In 1996, the Russians plan to launch a complex mission to Mars, including an orbiter, two small landers, and two penetrators. The various components each carry an international complement of instruments. The same year, the U.S. is to launch a small lander. In 1998, the Japanese are to send a spacecraft to characterize interactions of Mars with the solar wind. These are all missions that have been approved. Meanwhile approval is pending in the U.S. Congress for a Mars Program, that would include an orbiter in 1996 to recover most of the original Mars Observer objectives, and then multiple launches at subsequent opportunities. Discussions are also underway to design a Russian-launched mission in 1998 that includes a U.S. orbiter, a French balloon, and a Russian rover. In addition, the European Space Agency has received funding for studying how an international network mission in 2003 might be implemented. Because of the vulnerability of the exploration plan to funding and implementation problems, the International Mars Exploration Working Group will continue to meet to discuss implementation plans and to modify the exploration strategy should it become necessary. Moreover, several aspects of Mars exploration, in addition to the building, instrumenting and launching of vehicles to Mars, could benefit from an international approach. Examples are communication protocols between different vehicles, establishment of a communications infrastructure at Mars, adoption of uniform standards for scientific data, sharing of deep space communications facilities, and preparation of advanced missions such as sample return. Formulation of an international strategy is, thus, only a first step toward a broad international cooperative approach to Mars exploration.

An international Mars Exploration Program

A Mars Exploration Program to be executed by the international space community is being studied by the United States' National Aeronautics and Space Administration. This program is based on a set of separate missions, each conducted by different national space agencies, whose overall objective is to further the exploration of Mars by robotic means, provide precursor information for eventual human exploration of Mars, establish management relations which will carry forward to human exploration, and in the process contribute significantly to worldwide cooperation in the exploration of space and the prosperity of mankind. A mission set consisting of a high resolution imaging orbiter launched in the 1996 Mars opportunity, and a communications orbiter and rover with sample return elements launched in the 1998 opportunity, form the core of this proposed program. An optional variation would launch the sample return elements in 2001. The Martian atmospheric and surface samples would be returned to Earth approximately three years after the launch of the return elements. In addition to these core elements are penetrators, surface stations and balloons, each of which will make its own unique contribution. The responsibilities for the various elements would be allocated such that a space agency with extensive remote sensing expertise would design and implement an orbiter for the 1996 opportunity which would provide sub-meter resolution of the potential landing sites, certifying them safe from landing hazards and providing maps for planning rover traverses. In 1998 a rover would be launched to collect a variety of samples over a distance of some tens of kilometers. These samples would then be transferred to a vehicle for return to Earth. It is expected that the US and USSR would assume joint responsibility, with one nation implementing the rover and the other the sample return. Other nations or space agencies would provide the other elements which would become part of the Mars exploration infrastructure. All of the participating nations would have appropriate roles in the science investigations. A program of this complexity will inevitably present management challenges such as the establishment of mission objectives, development of the mission design, allocation of functional requirements to the flight elements, allocation of shared resources, e.g. time available on the Deep Space Network, coordination of schedules, coordination of flight and interface verification testing and coordination and conduct of mission operations, including data analysis. A key to meeting these challenges is a technical and management design that embodies efficient decision processes, simplified programmatic and technical interfaces and a non-adversarial environment.