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2018-04-01

Mars Landings Point to a Human Future

Since 1965, numerous robotic spacecraft have flown by, orbited or landed on Mars to send back to Earth information about this very different world.

Recently, Mars Global Surveyor gathered data for nine years with many of its pictures giving signs that liquid water might once have been on the planet’s surface. Although Mars is a cold, bleak wasteland with thin air that Earthlings could never breathe, we now have images of ice caps at Mars’ north and south poles.

On Earth, there is life almost everywhere there is cool, boiling hot or frozen water, but if water once flowed on Mars, did life thrive there too? Perhaps to “follow the water” on Mars is to locate water remaining underground, raising the possibility that bacteria and other tiny life forms have survived.

Exploration history and goals

The Mars exploration era began in October 1960, when the Soviet Union launched two probes known in the West as Marsnik 1 and Marsnik 2. The spacecraft were designed to perform flybys past the Red Planet, but neither even reached Earth’s orbit.

The United States mission began in 1964, launching the Mariner 3 spacecraft on an intended Mars flyby. The mission failed, but Mariner 4 succeeded, cruising past the Red Planet in July 1965 and returning 21 photos back to Earth.

The US sent a series of orbiters, landers and rovers to Mars in the following decades and in 1994, NASA announced the start of the Mars Exploration Program (MEP) led by the Jet Propulsion Laboratory (JPL) and NASA’s Science Mission Directorate (SMD). NASA’s ultimate objective is to send humans to Mars in the 2030s, but the MEP’s immediate goals are to provide a continuous flow of scientific information and discovery through a carefully selected series of robotic orbiters, landers and mobile laboratories interconnected by a high-bandwidth Mars/Earth communications network.

MEP currently operates rovers and orbiters on and around Mars, contributing to missions conducted by national and international partners, while developing future rover/orbiter missions. All scientific data and associated information are archived in the NASA Planetary Data System, while MEP missions mutually support each other in three key aspects:

Firstly, new data and scientific discoveries made by one mission can drive the scientific focus of future missions, such as certifying candidate landing sites;

Secondly, orbiter missions provide data for characterizing landed assets to provide a truthful and detailed context for orbital remote-sensing results;

And lastly, scientific observations from landed assets are interpreted in a broader context using research results from other areas of the planet, all of which help increase understanding of Mars as a system.

Mars exploration technologies

The Mars Exploration Program invests in its own exploratory technologies, while staying abreast of complementary innovations across NASA and the aerospace industry. The technology investment unique to Mars exploration includes the following equipment:

Mars Ascent Vehicle: Essential for returning materials (or people) from Mars, MEP is currently investing in propulsion and guidance technology to survive both the trip and Mars’ harsh surface environments. Hybrid rocket motors using paraffin fuel burned with liquid oxides of nitrogen are effective here, as aerodynamic controls such as fins require investment in Liquid Injection Thrust Vector Control (LITVC) to be effective within the thin Mars atmosphere. Using small ports to inject liquid oxidizer directly into the nozzle at different points, the direction of the MAV can be controlled quickly and effectively with no moving parts.

Planetary Protection Technologies: MEP is also investing in technologies to enable the safe transport and study of materials to Earth from Mars, including in-space metal brazing and explosive welding for containing samples and localized heat and plasma sterilization of containers.

Pathfinder and rovers

The rovers of Mars collect evidence of water and the chemical building blocks at the base of life. Mars Pathfinder was launched December 4, 1996 and landed on the planet’s Ares Vallis on July 4, 1997 as the first-ever robotic rover, returning an unprecedented amount of data to outlive its primary design life.

The Mars Pathfinder uses an innovative method of entering the Martian atmosphere directly, assisted by a parachute to slow its descent through the atmosphere and a giant system of airbags to cushion the impact. Both the lander and the 23-pound (10.6 kilogram) rover have provided engineering data on new scientific instruments to analyze the Martian atmosphere, its climate, geology and rock and soil composition.

Following a successful touchdown, the rover was named Sojourner after American civil rights crusader Sojourner Truth, while the lander was formally named the Carl Sagan Memorial Station. Both outlasted their design lives - the lander by nearly three times and the rover by 12 times.

Robot geologist explorers

In January 2004, two robotic geologists named Spirit and Opportunity landed on opposite sides of the red planet. Spirit landed at Gusev Crater, a possible former lake in a giant impact crater, while Opportunity landed at Meridiani Planum, the location of mineral deposits.

The mission’s first scientific goal was to locate and categorize a wide range of rocks and soils to provide clues to past water activity. Having far greater mobility than the 1997 Mars Pathfinder rover, these robotic explorers trekked for miles across the surface, conducting field geology and making atmospheric observations of ancient Martian environments where intermittently wet and habitable conditions existed.

Each rover bounced onto the surface inside a landing craft protected by airbags which deflated to open the landing craft. The rovers rolled out to take panoramic images giving scientists the information they needed to select promising geological targets. The rovers then drove to those locations to perform close-up scientific investigations.

The twin rovers sent hundreds of thousands of spectacular, high-resolution, full-color images to Earth, including detailed microscopic images of rocks and soil surfaces. Four different spectrometers have amassed unparalleled information about the chemical and mineralogical makeup of Martian rocks and soil; the rovers’ special rock abrasion tools enabling scientists to peer beneath the dusty and weathered surfaces of rocks to examine their interiors.

The data shows that past wet conditions might have supported microbial life, although unusual-looking bright patches of soil turned out to be extremely salty through prior contact with water. A study of “Eagle” and “Endurance” craters revealed evidence for past inter-dune lakes evaporating to form sulfate-rich sands reworked by water and wind, then solidified into rock and soaked by groundwater.

Grey hematite, which typically forms near water, was found in sphere-like grains (or “blueberries”) in Meridiani Planum, while Spirit’s initial travels in Gusev Crater revealed a more basaltic setting. After reaching the “Columbia Hills”, Spirit found a variety of rocks characterizing the earlier Mars in terms of impacts, explosive volcanism and subsurface water.

Both rovers exceeded their planned 90-day mission lifetimes by many years, with Spirit lasting 20 times longer than its original design and Opportunity continuing to operate more than a decade after launch. In 2015, Opportunity broke the record for extraterrestrial travel by rolling greater than the distance of a 26-mile (42-kilometer) marathon.

Mars 2020 expedition

The Mars 2020 mission will take the next step of searching for signs of past microbial life itself. The new rover will introduce a drill to collect core samples of the most promising rocks and soils, with potential future missions returning these samples to Earth for study. The mission also provides opportunities to demonstrate technologies for human Mars expeditions, including methods for producing oxygen from the atmosphere, identifying resources such as subsurface water, improving landing techniques and characterizing weather, dust and other potential environmental conditions.

Launch is timed for July/August 2020 when Earth and Mars are orbiting in positions from where it takes less power to travel there. To keep mission costs and risks as low as possible, the Mars 2020 design is based on NASA’s successful Mars Science Laboratory mission architecture, including its Curiosity rover and proven landing system.

Why explore Mars?

First, Mars is the most accessible place in the solar system. Second, exploring Mars could answer origin and evolution of life questions if not, someday, provide a home in which humankind could survive.

In the strategic sense, exploring Mars demonstrates political and economic leadership by aiming to improve the quality of life on Earth, helping us learn about our home planet and putting the US at the center of the peaceful, international exploration of space.

From a practical perspective, Mars is unique across the entire solar system as a terrestrial planet with an atmosphere and climate, but resembles Earth in having a very diverse and complex geology and a climate that has changed over its history. As many of the key questions of solar system science can be addressed by exploring Mars, missions have served to inspire the next generation of explorers and to expand human knowledge dramatically.

From Robots to Humans

Mars may once have been warm and wet, but it is now a cold, dry, barren place. The atmosphere is thin and mainly carbon dioxide. Ultraviolet and other forms of intense radiation bathe the surface because Mars has a thin atmosphere and no active magnetic field to protect it.

The primary geological processes currently shaping its surface are impact cratering, wind-driven transport of sediment, condensation/sublimation of water and carbon dioxide ice and landslides. The presence of very large volcanoes at the surface indicates that Mars has been getting rid of heat. But how warm is the interior of Mars? Is there seismic activity (Marsquakes) or even life on Mars today?

NASA has begun searching for suitable locations for humans to land in locations of high scientific value to provide resources for explorers to land, live and work on Mars. Locally derived natural resources such as water and oxygen are crucial, with liquid water potentially extracted from the atmosphere, from hydrated minerals or from ground ice if not ice buried beneath the surface. In fact, oxygen can be generated from the carbon dioxide making up most of Mars’ atmosphere, while the Mars 2020 rover mission will include the MOXIE tool providing the technology for oxygen generation.

NASA will be launching the Insight mission in 2018 to study the interior of Mars and obtain sophisticated geophysical measurements, including heat flow and measurement of seismic activity. But in 2020 alone, five other space missions are scheduled to launch: the ExoMars rover (European Space Agency), the United Arab Emirates Hope Orbiter, a Japanese orbiter, a Chinese rover and a SpaceX Dragon capsule.

NASA is also planning to send humans to Mars sometime in the future with preparations being made for robotic exploration in collaboration with the Human Exploration and Operations Mission Directorate (HEOMD) and the Space Technology Mission Directorate (STMD). The Mars 2020 rover will help increase understanding of the current weather, winds, radiation and dust environment, while trialing technologies that will help human landing.

Reference Text/photo

www.space.com

www.nasa.gov

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