17 November 1998
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Ron Baalke
Mars Surveyor 98 Webmaster
JPL News
17 November 1998
Mars Climate Orbiter, scheduled for launch Dec. 10, and Mars Polar Lander, scheduled for launch Jan. 3, will seek clues to the history of climate change on Mars. Both will be launched atop identical Delta II launch vehicles from Launch Complex 17 A and B at Cape Canaveral Air Station, FL, carrying instruments to map the planet's surface, profile the structure of the atmosphere, detect surface ice reservoirs and dig for traces of water beneath Mars' rusty surface.
The lander also carries a pair of basketball-sized microprobes that will be released as the lander approaches Mars and dive toward the planet's surface, penetrating up to about 1 meter (3 feet) underground to test 10 new technologies, including a science instrument to search for traces of water ice. The microprobe project, called Deep Space 2, is part of NASA's New Millennium Program.
The missions are the second installment in NASA's long-term program of robotic exploration of Mars, which was initiated with the 1996 launches of the currently orbiting Mars Global Surveyor and the Mars Pathfinder lander and rover.
The 1998 missions will advance our understanding of Mars' climate history and the planet's current water resources by digging into the enigmatic layered terrain near one of its poles for the first time. Instruments onboard the orbiter and lander will analyze surface materials, frost, weather patterns and interactions between the surface and atmosphere to better understand how the climate of Mars has changed over time.
Key scientific objectives are to determine how water and dust move about the planet and where water, in particular, resides on Mars today. Water once flowed on Mars, but where did it go? Clues may be found in the geologic record provided by the polar layered terrain, whose alternating bands of color seem to contain different mixtures of dust and ice. Like growth rings of trees, these layered geological bands may help reveal the secret past of climate change on Mars and help determine whether it was driven by a catastrophic change, episodic variations or merely a gradual evolution in the planet's environment.
Today the Martian atmosphere is so thin and cold that it does not rain; liquid water does not last on the surface, but quickly freezes into ice or evaporates and resides in the atmosphere. The temporary polar frosts which advance and retreat with the seasons are made mostly of condensed carbon dioxide, the major constituent of the Martian atmosphere. But the planet also hosts both water-ice clouds and dust storms, the latter ranging in scale from local to global. If typical amounts of atmospheric dust and water were concentrated today in the polar regions, they might deposit a fine layer every year, so that the top meter (or yard) of the polar layered terrains could be a well-preserved record showing 100,000 years of Martian geology and climatology.
Nine and a half months after launch, in September 1999, Mars Climate Orbiter will fire its main engine to put itself into an elliptical orbit around Mars. The spacecraft will then skim through Mars' upper atmosphere for several weeks in a technique called aerobraking to reduce velocity and circularize its orbit. Friction against the spacecraft's single, 5.5-meter-long (18-foot) solar array will slow the spacecraft as it dips into the atmosphere each orbit, reducing its orbit period from more than 14 hours to 2 hours.
Finally, the spacecraft will use its thrusters to settle into a polar, nearly circular orbit averaging 421 kilometers (262 miles) above the surface. From there, the orbiter will await the arrival of Mars Polar Lander and serve as a radio relay satellite during the lander's surface mission. After the lander's mission is over, the orbiter will begin routine monitoring of the atmosphere, surface and polar caps for a complete Martian year (687 Earth days), the equivalent of almost two Earth years.
The orbiter carries two science instruments: the Pressure Modulator Infrared Radiometer, a copy of the atmospheric sounder on the Mars Observer spacecraft lost in 1993, and the Mars Color Imager, a new, light-weight imager combining wide-and medium-angle cameras. The radiometer will measure temperatures, dust, water vapor and clouds by using a mirror to scan the atmosphere from the Martian surface up to 80 kilometers (50 miles) above the planet's limb.
Meanwhile, the imager will gather horizon-to-horizon images at up to kilometer-scale (half-mile-scale) resolutions, which will then be combined to produce daily global weather images. The camera will also image surface features and produce a map with 40-meter (130-foot) resolution in several colors, to provide unprecedented views of Mars' surface.
Mars Polar Lander, launched a month after the orbiter is on its way, will arrive in December 1999, two to three weeks after the orbiter has finished aerobraking. The lander is aimed toward a target sector within the edge of the layered terrain near Mars' south pole. The exact landing site coordinates will be adjusted as late as August 1999, based on images and altimeter data from the currently orbiting Mars Global Surveyor.
Like Mars Pathfinder, Mars Polar Lander will dive directly into the Martian atmosphere, using an aeroshell and parachute scaled down from Pathfinder's design to slow its initial descent. The smaller Mars Polar Lander will not use airbags, but instead will rely on onboard guidance and retro-rockets to land softly on the layered terrain near the south polar cap a few weeks after the seasonal carbon dioxide frosts have disappeared. After the heat shield is jettisoned, a camera will take a series of pictures of the landing site as the spacecraft descends.
As it approaches Mars about 10 minutes before touchdown, the lander will release the two Deep Space 2 microprobes. Once released, the projectiles will collect atmospheric data before they crash at about 200 meters per second (400 miles per hour) and bury themselves beneath the Martian surface. The microprobes will test the ability of very small spacecraft to deploy future instruments for soil sampling, meteorology and seismic monitoring. A key instrument will draw a tiny soil sample into a chamber, heat it and use a miniature laser to look for signs of vaporized water ice.
About 100 kilometers (60 miles) away from the microprobe impact sites, Mars Polar Lander will dig into the top of the terrain using a 2-meter-long (6-1/2-foot) robotic arm. A camera mounted on the robotic arm will image the walls of the trench, viewing the texture of the surface material and looking for fine-scale layering. The robotic arm will also deliver soil samples to a thermal and evolved gas analyzer, an instrument that will heat the samples to detect water and carbon dioxide. An onboard weather station will take daily readings of wind temperature and pressure, and seek traces of water vapor. A stereo imager perched atop a 1.5-meter (5-foot) mast will photograph the landscape surrounding the spacecraft. All of these instruments are part of an integrated science payload called the Mars Volatiles and Climate Surveyor.
Also onboard the lander is a light detection and ranging (lidar) experiment provided by Russia's Space Research Institute. The instrument will detect and determine the altitude of atmospheric dust hazes and ice clouds above the lander. Inside the instrument is a small microphone, furnished by the Planetary Society, Pasadena, CA, which will record the sounds of wind gusts, blowing dust and mechanical operations onboard the spacecraft itself.
The lander is expected to operate on the surface for 60 to 90 Martian days through the planet's southern summer (a Martian day is 24 hours, 37 minutes). The mission will continue until the spacecraft can no longer protect itself from the cold and dark of lengthening nights and the return of the Martian seasonal polar frosts.
The Mars Climate Orbiter, Mars Polar Lander and Deep Space 2 missions are managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. Lockheed Martin Astronautics Inc., Denver, CO, is the agency's industrial partner for development and operation of the orbiter and lander spacecraft. JPL designed and built the Deep Space 2 microprobes. JPL is a division of the California Institute of Technology, Pasadena, CA.
NASA Headquarters, Washington, DC
Jet Propulsion Laboratory, Pasadena, CA
April 8, 1998
Two identical probes will be carried as a secondary payload on the lander, due for launch in January 1999. Following an 11- month cruise, the Microprobes will separate from the lander before it enters the Martian atmosphere, and then hit the ground at approximately 400 mph.
During the impact, each microprobe will separate into two sections: the forebody and its instruments will penetrate up to six feet (two meters) below the surface, while the aftbody will remain near the surface to communicate with a radio relay on NASA's Mars Global Surveyor orbiter while making meteorological measurements.
The nine selected scientists are:
The scientific objectives of the Mars Microprobes include searching for the presence of water ice in the soil and characterizing its thermal and physical properties. A small drill will bring a soil sample inside the probe, heat it, and look for the presence of water vapor using a tunable diode laser. An impact accelerometer will measure the rate at which the probes come to rest, giving an indication of the hardness of the soil and any layers present. Temperature sensors will estimate how well the Martian soil conducts heat, a property sensitive to different soil properties such as grain size and water content. A sensor at the surface will measure atmospheric pressure in tandem with a sensor on the Mars Polar Lander.
The Mars Microprobes mission, also known as Deep Space-2 (DS- 2), is scheduled to be the second launch in NASA's New Millennium Program of technology validation flights, designed to enable advanced science missions in the 21st century.
"I'm delighted with the selection of this excellent group of investigators. The Mars Microprobe will give us a glimpse of the subsurface of Mars, which in many ways is a window into the planet's history," said Dr. Suzanne Smrekar, the DS-2 project scientist at NASA's Jet Propulsion Laboratory, Pasadena, CA. "The region of Mars we will explore is similar to Earth's polar regions in that it is believed to collect ice and dust over many millions of years. By studying the history of Mars and its climate, we are likely to better understand the more complex system on our own planet."
In addition to the miniaturized science instruments capable of surviving high velocity impact, technologies to be tested on DS-2 include a non-erosive, lightweight, single-stage atmospheric entry system or aeroshell; power microelectronics with mixed digital/analog advanced integrated circuits; an ultra-low temperature lithium battery; an advanced three-dimensional microcontroller; and flexible interconnects for system cabling.
"The combination of a single-stage entry vehicle with electronics and instrumentation that can survive very high impact loads will enable us to design a whole new class of very small, rugged spacecraft for the in-situ exploration of the planets," explained Sarah Gavit, DS-2 project manager at JPL.
"Slamming high-precision science instruments into the surface of Mars at 400 mph is very challenging, no doubt about it! But once this type of technology is demonstrated, we can envision future missions that could sample numerous regions on Mars or make network measurements of global weather and possible Marsquakes," said DS-2 program scientist Dr. Michael Meyer of NASA Headquarters, Washington, DC.
Further information on DS-2 is available on the Internet.
The New Millennium Program is managed by JPL for NASA's Office of Space Science in Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
Univeristy of Arizona
April 8, 1998
Mars Microprobe Project web site
Death of a Watery World (in New Scientist)
A planetary scientist from The University of Arizona in Tucson has been named to the science team for an experiment piggybacking on the 1998 Mars Surveyor Lander, a mission that carries UA instruments in the main payload package.
NASA today named Ralph D. Lorenz, 28, a research associate in the UA Lunar and Planetary Laboratory, to the science team of the $2.8 million Mars Microprobe Project that will ride on the 98 lander mission, scheduled for launch in January 1999. Lorenz, who models planetary climates, also works on a UA-built experiment called TEGA, part of the Mars Volatiles and Climate Surveyor (MVACS), the integrated payload package on the lander.
The microprobes are two basketball-size aeroshells that will ride underneath the lander s solar panels during the spacecraft s 11 month journey to Mars. They will crash onto the Martian surface at a velocity of about 200 meters per second. Each aeroshell will shatter on impact, releasing a miniature two-piece science probe that will punch into the soil at a depth of up to 2 meters. The microprobes are primarily to test key technologies for future missions that will land multiple microprobes on the surfaces of other worlds, but they also have a major science goal, which is to determine if water ice is present in the Martian subsurface. The tiny science stations will also measure temperature and monitor local Martian weather for 50 hours in the very cold Mars environment.
Whether batteries on the microprobes survive impact is uncertain, Lorenz noted. So far, no penetrator has successfully reached another planet or moon. The penetrators will strike the surface with a force equivalent to 80,000 times their weight here on Earth, he added.
The 98 Mars Surveyor Lander is to discover what turned Mars from a warm, wet place to the cold, arid planet we see today. It is targeted to land on the strange layered terrain at the edge of the south polar ice cap. Here, Lorenz wrote in the Sept. 20, 1997, issue of New Scientist, a record of the Martian climate may be written in the geology of the area in the same way that the climate record on Earth is reflected in ocean sediments, ice cores and tree rings. Lorenz plans to look for layers beneath the surface by analyzing the impact force recorded by an accelerometer on each microprobe.
The three main theories of what happened to transform Mars climate read like the plot of a detective novel, Lorenz wrote. Mars volatiles may have been murdered by slow, drawn-out death by suffocation as impacts from asteroids and comets eroded the atmosphere. Or perhaps it was death by suicide, a case where Martian silicate rocks reacted with atmospheric carbon dioxide to form carbonate minerals: The atmosphere would gradually have been sucked into the surface of the planet. Or maybe the Red Planet died of natural causes that resulted when, gripped in a severe ice age, the planet s carbon dioxide atmosphere condensed to form permafrost at the poles or beneath the entire surface. The permafrost would be hidden from orbiting spacecraft by the dust that covers Mars.
The main solar-powered payload, MVACS, should collect data for up to seven months during the Martian summer of 1999. During that time it should provide vital clues to the planet s cause of death, Lorenz said. When the winter sun sinks low on the Mars horizon, MVAC s solar panels will no longer power the lander. But scientists hope that MVACS may come back to life the following spring, almost 400 days later, he added.
UA planetary sciences professor William V. Boynton heads the team that built the TEGA, or Thermal and Evolved Gas Analyzer, on MVACS. It consists of eight tiny ceramic ovens, each no wider across than a dime, that will use electric current to heat soil samples scooped up by the robotic arm. By measuring the amount of energy required to warm the soil at a certain rate, scientists will detect how much frozen water and carbon dioxide are in the soil, as well as the presence of various minerals.
Peter H. Smith, principal investigator on the Imager for Mars Pathfinder (IMP) and an associate research scientist at the UA Lunar and Planetary Laboratory, heads the team that built the Surface Stereo Imager, or SSI, for the 98 Mars Surveyor Lander. It is a copy of the stereoscopic, color-sensitive IMP. Smith s team also built the Robotic Arm Camera, or RAC, on MVACS. It is a more near-sighted camera mounted at the end of a two-meter robotic arm. The arm will collect surface and subsurface samples of Martian soil. RAC will take close-up pictures of these samples.
NASA Headquarters, Washington, DC
Jet Propulsion Laboratory, Pasadena, CA
November 13, 1997
This successful check of the batteries and soil collection drill of the mission known as Deep Space 2 (DS2) provides a "green light" for subsequent integrated system tests next spring, said Sarah Gavit, DS2 project manager at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA. The DS2 mission hardware will be launched in January 1999, mounted on the Mars Surveyor '98 Lander. Both missions will arrive on Mars in December 1999.
DS2 is the second scheduled launch in NASA's New Millennium Program, which is designed to test new advanced technologies prior to their use on science missions in the 21st century. DS2 will validate the ability of small probes loaded with sensitive, miniaturized instruments to analyze the terrain of planets and moons throughout the Solar System.
In the late October test, a 4.4-pound (two-kilogram) prototype probe containing a soil collection drill and a circular group of eight lithium thyonal chloride cells -- forming two batteries -- was shot into the ground at more than 400 mph (644 kilometers per hour). The drill survived a 20,000-G impact, and the batteries, nestled inside a custom-designed casing, survived a 45,000-G impact intact. Both continued to function as designed. One G is the normal force of gravity on Earth.
"The Mars Pathfinder lander experienced about 19 G's when it hit the Martian terrain in July, so you can see that we are working at enormous rates of deceleration," explained Gavit. "One of our biggest challenges has been to find a way for our components to survive such a high deceleration force. The items at highest risk are the batteries, their packaging and the motor drill assembly.
"Although the recent test was one in a long series, it was the first test using flight-like hardware and packaging, so it served as a complete qualification of the battery and drill subsystems," she added.
The probe design features two modules: a circular aftbody, five inches (13 centimeters) in diameter, containing the batteries, that remains atop the surface; and a four-inch-long (10-centimeter) forebody, containing the drill and a soil analysis instrument, that should burrow up to six feet (1.8 meters) into the Martian soil. The two modules are connected via a flex cable that unravels as the forebody dives into the soil after a freefall impact.
Once in the ground, the soil collection drill slowly twists out from the side of the forebody and retracts a tiny soil sample into a chamber within the forebody, where it is analyzed by a water detection instrument. This instrument's key feature is a miniature tunable diode laser, similar in principle to the lasers used in consumer CD players. The soil sample is then heated, creating a vapor that passes through the path of the laser beam if water is indeed present. This resulting change in the intensity of the laser light indicates the amount of water, if any, to be found in the Martian soil sample.
The aftbody features batteries developed just for DS2. These batteries can operate down to minus 112 degrees F (minus 80 degrees Celsius), making them the only batteries of this type with the dual capability of being able to survive the strong impact and work in low temperatures. The aftbody also includes a micro- telecommunications system that, together with miniaturized electronics in the forebody, will relay the probe's findings to the orbiting Mars Global Surveyor spacecraft for transmission to Earth via NASA's Deep Space Network.
The Oct. 29 test took place at the New Mexico Institute of Mining Technology's Energetic Materials Research and Test Center in Socorro, NM. It was the 53rd test of DS2 hardware since the spring of 1996, beginning with early tests of preliminary battery and drill designs, among many other components.
Additional information can be obtained by visiting the DS2 World Wide Web site.
JPL manages the New Millennium Program for NASA's Office of Space Science and Office of Mission to Planet Earth, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
NASA Headquarters, Washington
Jet Propulsion Laboratory, Pasadena, CA
September 24, 1996
Two small science probes will be sent to Mars in 1999 to demonstrate innovative new technologies brought to the forefront by NASA's New Millennium program.
Under terms of a new agreement between the New Millennium and Mars Exploration programs, the microprobes will hitchhike to Mars aboard NASA's 1998 Mars Surveyor Lander.
"A successful demonstration of the microprobe technologies will enable a wide range of scientific activities that would not be affordable with conventional technologies," said Dr. John McNamee, manager of the 1998 Mars Surveyor Lander and Orbiter project at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA.
"In particular, scientific investigations which require a relatively large number of surface stations distributed over the surface of Mars, such as seismic or meteorology networks, will be made possible by the microprobe concept," McNamee said. "In addition, microprobe penetrators may be the most efficient and effective way of obtaining soil samples and measurements from below the sterilized Martian surface."
In the process of enabling future characterization of the Martian climate by a meteorological network, the Mars microprobes will complement the climate-related scientific focus of the 1998 Mars Surveyor Lander by demonstrating an advanced, rugged microlaser system for detecting subsurface water. Such data on polar subsurface water, in the form of ice, should help put limits on scientific projections for the global abundance of water on Mars.
Future missions to the planet could use similar penetrators to search for subsurface ice and minerals that could contribute to the search for evidence of life on Mars.
The 1998 Mars Surveyor Lander will be launched in January 1999 and spend 11 months en route to the Red Planet. Just prior to its entry into the Martian atmosphere, the microprobes, mounted on the spacecraft's cruise ring, will separate and plummet to the surface using a single-stage entry aeroshell system. Chosen for its simplicity, this aeroshell does not separate from the microprobes, as have traditional aeroshells on previous spacecraft, such as the Mars Pathfinder and the Viking landers of the mid-1970s.
The probes will plunge into the surface of Mars at an extremely high velocity of about 446 miles per hour (200 meters per second) to ensure maximum penetration of the Martian terrain. They should impact the surface within 120 miles (200 kilometers) of the main Mars '98 lander, which is targeted for the planet's icy south polar region.
Upon impact, the aeroshells will shatter and the microprobes will split into a forebody and aftbody system. The forebody, which will be lodged between one to six feet underground, will contain the primary electronics and instruments. The aftbody, connected to the forebody by an electrical cable, will stay close to the surface to collect meteorological data and deploy an antenna for relaying data back to Earth.
The microprobes will weigh less than 4.5 pounds (2 kilograms) each and be designed to withstand both very low temperatures and high deceleration. Each highly integrated package will include a command and data system, a telecommunications system, a power system, and primary and secondary instruments. Nearly all electrical and mechanical designs will be new to space flight.
"In addition to a team of industrial partners that will help develop advanced technologies to be demonstrated during the mission, we have just selected Lockheed Martin Electro-Optical Systems as a primary industry partner to participate in the integration and test program for the microprobes," said Sarah Gavit, Mars microprobe flight leader at JPL.
Technologies proposed for demonstration on this second New Millennium flight include a light weight, single- stage entry aeroshell, a miniature, programmable telecommunication subsystem, power microelectronics with mixed digital/analog integrated circuits, an ultra low- temperature lithium battery, a microcontroller and flexible interconnects for system cabling.
In-situ instrument technologies for making direct measurements of the Martian surface will include a water and soil sample experiment, a meteorological pressure sensor and temperature sensors for measuring the thermal properties of the Martian soil.
"The Mars microprobe mission will help chart the course for NASA's vision of space science in the 21st century, a vision that incorporates the concept of 'network science' through the use of multiple planetary landers," said Kane Casani, manager of the New Millennium program. The probes will become the first technology to be validated in this new network approach to planetary science.
"Networks of spacecraft will address dynamic, complex systems," Casani said. "For example, a single lander can report on the weather at one spot on a planet, but a network of landers is needed to characterize the planet's dynamic climate. Similarly, a single seismometer will indicate if a quake has occurred on a planet, but a network of seismometers can measure the size of a planetary core. We need multiple spacecraft to go beyond our initial reconnaissance to completely characterize dynamic planetary systems the way we are able to do on Earth."
The New Millennium program is managed by JPL for NASA's Office of Space Science and Office of Mission to Planet Earth, Washington, DC. The Mars `98 lander, managed by JPL for the Office of Space Science, is in development at Lockheed Martin Astronautics Corp., Denver, CO, under contract to JPL.
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