May 3, 2017

In Andy Weir’s 2011 book The Martian and its 2015 film adaptation,  botanist-astronaut Mark Watney manages to grow potatoes while marooned on Mars. Watney hauls Martian soil into a pressurized, climate-controlled base and harvests a crop that provides food while his other supplies run out. Today, a group of Peruvian scientists are working on transferring this fiction to reality. Agricultural researchers from the International Potato Center (called the Centro Internacional de la Papa in Spanish, or CIP) in Lima, the Peruvian capital, have grown some rather hardy potatoes in an even worse environment than Watney’s Martian garden. The scientists’ research, carried out in the Andes Mountains of South America (where potatoes originated), might make farming on Mars or other barren places possible.

Scientists at the International Potato Center in Lima, Peru, grew a “Unique” potato in simulated Martian conditions within the container at left, called the “CubeSat.” Credit: © International Potato Center

Human exploration of Mars is one of the primary long-term goals of such space agencies as the United States National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). But before people get there, scientists must solve a host of problems. First among them will be how to feed astronauts during an extended stay in the harsh environment of the Red Planet.

Potatoes originated in the often harsh environment of the Andean Highlands of South America. Credit: © Roux Frederic, Shutterstock

The ability to grow food during a space journey or while on the Martian surface has a number of benefits. Space could be saved in the spacecraft, allowing for other needed supplies, and instead of freeze-dried or tubular “astronaut food,” space explorers could eat a variety of freshly grown produce. But growing food on Mars—an extremely cold, dry, and nearly airless planet—will not be easy. Life as we know it cannot survive on its surface—yet.

The ability to grow food on Mars will greatly help in the planet’s exploration and possible settlement. Credit: NASA/JPL/Malin Space Science Systems

In Peru, the CIP scientists wanted to see if certain hardy potatoes could be grown in conditions similar to those found on Mars. To do this, the scientists built a sealed growing chamber (a garden in a box they called a “CubeSat”) and layered it with nutrient-weak, sandy soil similar to that found on Mars. They installed low-powered lights on a longer-than-Earth day-night cycle, and created a low-temperature and low-atmospheric pressure environment. They then tried growing dozens of varieties of potatoes in the simulator, irrigating them with nutrient-rich water. Of all the tested varieties, one called “Unique” grew best under the extreme conditions.

The Unique potato is exceptionally hardy, but it could not possibly grow on the surface of Mars without human intervention. The scientists grew the potatoes at temperatures around freezing, but surface temperatures on Mars can dip below -150 °F (-100 °C) at night. They were able to achieve growth with somewhat reduced atmospheric pressure (like the thin air at the top of the Andes Mountains), but Mars’s atmospheric pressure is a mere 0.7 percent of the atmospheric pressure on Earth. And, as far as we know, there is no nutrient-rich water on Mars. Liquid water near the Martian surface is only present during the planet’s summer, and it is extremely salty.

Potatoes are one of the world’s most important crops. The ability to grow potatoes and other crops in harsh conditions could prove vastly important as climate change alters the global environment. Credit: © David R. Frazier

The CIS experiment provided scientists and engineers with useful information on the extreme limits of vegetable cultivation. With the use of extremely hardy plants like the Unique potato, astronaut greenhouses could be kept cooler than Earth spaces, saving valuable electricity for purposes other than heating. Because plants can survive on carbon dioxide concentrations, excess carbon dioxide exhaled by astronauts could help provide the space garden’s protected atmosphere. If Martian soil could be manipulated for vegetable growth, it would negate the need to send bundles of Earth soil to the Red Planet.

Beyond its applications to space travel or Martian living, the CIS potato research has a more practical use here on Earth. As the climate changes from global warming, environmental conditions will become harsher in many places around the world. By studying how crops survive in extreme conditions, agricultural scientists may be able to discover and breed crops more resistant to the worst effects of climate change.

December 20, 2016

Researchers led by Cassie Stuurman of the University of Texas, Austin, recently used the Mars Reconnaissance Orbiter (MRO) to discover a vast deposit of ice beneath the surface of Mars. They published their findings in late November in the journal Geophysical Research Letters. To future human explorers, the ice deposit could prove more valuable than gold.

Large deposits of ice have been discovered beneath the surface of Mars, the fourth planet from the sun. Credit: NASA/JPL/Malin Space Science Systems

The MRO, launched by the United States National Aeronautics and Space Administration (NASA) in 2005, carries the highest resolution camera ever sent to Mars. The camera is capable of resolving (distinguishing) objects on the planet’s surface less than 1 meter (3 feet) across. Its high-resolution images helped identify safe landing sites for subsequent Mars landers and discovered recurring slope lineae, patterns on Martian hills and valleys likely formed by the flow of liquid water just below ground. The MRO payload also includes a high-resolution spectrometer that has mapped the occurrence of minerals formed in association with water; an instrument that measures temperatures, pressures, and dust concentrations throughout the Martian atmosphere; and ground-penetrating radar that can detect layered rocks and ice beneath the surface.

Images such as this one, showing curved depressions in Mars’s Utopia Planitia region, prompted NASA to use ground-penetrating radar aboard the Mars Reconnaissance Orbiter to check for underground ice. Credit: NASA/JPL-Caltech/Univ. of Arizona

This radar detected ice in a region called Utopia Planitia (planitia is a Latin word that can mean low plain or basin). It is the largest confirmed impact basin in the solar system, with a diameter of 2,100 miles (3,300 kilometers). An impact basin is a vast hollow created by a large asteroid or comet strike. The angular cracks and rimless pits in the Martian impact basin resemble similar surface features in Canada that mark underground ice deposits. The researchers estimate that the Martian ice deposit holds more water than North America’s Lake Superior, the largest body of fresh water on Earth. The deposit is buried beneath as little as 3 feet (1 meter) and as much as 33 feet (10 meters) of Martian soil. The deposit is not solid ice, but rather is 50 to 85 percent ice, with rock, dust, and other materials mixed in.

Billions of years ago, Mars was warmer than it is today. Oceans and streams of liquid water probably covered its surface. But the solar wind (continuous flow of particles from the sun) stripped away most of Mars’s atmosphere, causing much of the water to escape into space. Today, the surface of Mars is cold, dry, and dusty. Some water remains on Mars, however, frozen in underground deposits at the poles and other places around the planet.

The newly discovered ice deposit may have important implications for the eventual human exploration and colonization of Mars. Other such deposits exist on the planet, but most are small and found in areas with rough terrain. Mars’s poles are covered with large ice caps, but they are the coldest regions of the planet. Utopia Planitia is a large, flat basin located in the somewhat warmer mid-latitudes. Therefore, future Mars colonists may be able to land a spacecraft in Utopia Planitia and find water not far from their landing site. Such water could be used for drinking, growing crops, and creating rocket fuel for journeys back to Earth. Studying the ice could also help explain the history of Mars’s climate.

November 3, 2016

Last month, on October 19, Mars claimed another victim. A landing module named Schiaparelli, designed by the European Space Agency (ESA) and Russia’s space agency, Roscosmos, accidentally smashed into the Martian surface at more than 180 miles (300 kilometers) per hour. Schiaparelli (named for the Italian astronomer Giovanni Schiaparelli, who studied Mars in the late 1800′s) was destroyed, but the mission was not a total failure. The Mars Trace Gas Orbiter (TGO), launched with Schiaparelli, successfully entered into orbit around the Red Planet.

This artist’s impression shows the Trace Gas Orbiter and Schiaparelli (the small circular knob facing toward Mars) during the seven-month ExoMars voyage to the Red Planet. Credit: ESA/David Ducros

Despite is relatively inviting appearance, Mars is extremely difficult to explore. Of all the missions sent there, nearly two-thirds have failed before completing their planned experiments and observations. Landing on Mars is particularly difficult. The planet’s atmosphere is extremely thin, which means that parachutes and similar braking devices don’t work as well as they do in the much denser atmosphere of Earth. Mars is also a relatively large planet, and its significant gravitational pull forces a lander to carry large amounts of fuel for its rockets to slow the descent. On the surface, craggy rocks, enormous sandstorms, and frigid temperatures conspire to damage a lander as it settles into a safe resting place.

The ESA and Roscosmos launched ExoMars 2016, which consisted of Schiaparelli and the TGO, in March of this year. The lander was equipped with a parachute and rockets to slow its entry through the Martian atmosphere. The parachute deployed, but it ejected far too soon. To make matters worse, the rockets, which were supposed to fire for about 30 seconds, fired for only a few seconds before shutting off. Project engineers think these malfunctions stemmed from a software glitch that led the lander to act as though it was already on the Martian surface. Instead, it was actually plummeting through the Martian atmosphere. With nothing to slow it, Schiaparelli crashed into the Red Planet’s surface and exploded.

ExoMars 2016 did not function as the European scientists had hoped, but it could still be a successful mission. Schiaparelli was not intended to add much to the science output of the mission. It had enough power to survive only a few Martian days. Its primary objective was to demonstrate landing technology for the ambitious ExoMars 2020, which will attempt to land a rover on Mars. Mission leaders can take heart in the fact that the lander seems to have been doomed by a software failure, a problem much easier to fix than a hardware failure. But it will be small consolation to an ExoMars program that is already behind schedule and over budget.

The Trace Gas Orbiter, however–a crucial part of the future ExoMars mission–entered into orbit around Mars and appears to be functioning normally. The TGO will examine methane and other gases in the Martian atmosphere. It will help determine if this methane is the result of geological or biological processes. Scientists have not found direct evidence of life on Mars, but some think tiny organisms could exist below its surface. The TGO will also serve as a data relay center for the ExoMars 2020 rover, receiving commands from Earth for the rover and data from the rover to be sent back to Earth. Let’s just hope ESA and Roscosmos can stick the landing on the next try!

September 7, 2016

On August 28, six brave explorers breathed the fresh air of Earth for the first time in a year. Since last August, they had been living in an isolated dome, only able to step outside wearing full space suits. They had limited contact with the outside world and had to make do with whatever supplies they had with them. In truth, however, the explorers never left Earth. These six people were simulating what life would be like on a Mars mission—and they were doing it from the “tropical paradise” of Hawaii. The team included a French astrobiologist, a German physicist, and four Americans: an architect, a journalist, a pilot, and a soil scientist.

A HI-SEAS team member takes a stroll along the Martian-like slopes of Mauna Loa volcano in Hawaii. Credit: © Sian Proctor, University of Hawaii

Mars is the fourth planet from the sun and the next planet beyond Earth in our solar system. Of all the planets in our solar system, Mars has the surface environment that most closely resembles that of Earth. Mars has weather and seasons and familiar landforms. Salty water may flow just below the Martian surface. Because of the Red Planet’s relatively familiar appearance, many see it as the next logical place for human exploration.

The interior of the HI-SEAS dome provides all the comforts of home, or, at least, a home on Mars. Credit: © Zak Wilson, HI-SEAS/University of Hawaii

The six people were part of the fourth Hawaii Space Exploration Analog and Simulation (HI-SEAS), conducted by the United States National Aeronautics and Space Administration (NASA). They lived isolated in a dome on Mauna Loa, a huge shield volcano. The craggy red terrain of the volcano resembles the Martian surface. During a HI-SEAS mission, crew members conduct experiments, deal with unforeseen events, and live with limited resources and contact from the outside world. Whenever they left their habitation module to explore the volcano, they would don full space suits. All communication with the rest of the world was delayed by 20 minutes to simulate the time it takes for radio signals to travel between Earth and Mars. The explorers ate bland diets of food that could survive long-duration storage. They also had to maintain their habitat and repair any systems that failed.

On Aug. 28, 2016, happy HI-SEAS explorers “return to Earth” after 365 days of a simulated Mars mission in Hawaii. Credit: © University of Hawaii

While it may sound like high-concept make-believe, experiments like this one will help NASA better prepare future astronauts for long-term space missions, such as a journey to Mars. During such missions, astronauts will be crammed together in small spaces for months or years on end. Simply reaching Mars from Earth will take six months. Maintaining the mental health of the crew will be just as important as keeping any mechanical system in working order. Astronauts will have to cope with boredom and homesickness and avoid interpersonal conflict to accomplish tasks millions of miles from any outside help. The data gathered from HI-SEAS expeditions will help them know what to expect.

This was the longest HI-SEAS mission to date, but it is not the longest Martian simulation. That honor belongs to Russia’s Mars-500 project in 2010-2011, in which another six-person crew endured 520 days of isolation.

March 18, 2016

ExoMars 2016 hopes to find evidence of life on Mars, the fourth planet from the sun.
Credit: NASA/JPL/Malin Space Science Systems

On Monday, March 14, a rocket blasted off for Mars. The joint mission of the European Space Agency (ESA) and the Russian Federal Space Agency (Roscosmos) will arrive at the Red Planet in October. When it reaches orbit, ExoMars 2016 will sniff the Martian atmosphere to see if it smells like life.

Mars is the fourth planet from the sun. Today, it is a cold, desolate place. It orbits some 142 million miles (228 million kilometers) away from the sun, about 1 ½ times the distance at which Earth orbits. Its atmosphere is about 100 times less dense than Earth’s. Water exists there only as ice or in small, briny, subsurface streams in the Martian summer. Mars has no global magnetic field to protect it from harmful solar radiation. It is hard to imagine life—even bacteria—eking out an existence in such a place.

Deep channels descending a crater wall on Mars showing evidence of water. Credit: NASA

For a brief time after it formed some 4.6 billion years ago, however, scientists think that Mars was a warmer, wetter planet, much like Earth. Since scientists think life emerged on Earth shortly after its formation, it is possible that life arose on Mars at this time as well, when conditions were more favorable. If it developed, this early life could have gone extinct as Mars cooled and its atmosphere was blown away by the solar wind. Some of it, however, could have survived, most likely as microscopic organisms living underground. Determining whether Mars has hosted or still hosts life is extremely important in figuring out how common or rare life is in the universe. If it developed twice in the same solar system, the odds are good that it developed elsewhere, too.

ExoMars 2016 consists of two modules: the Trace Gas Orbiter and an entry, descent, and landing demonstrator nicknamed Schiaparelli (after Italian astronomer Giovanni Schiaparelli). The Trace Gas Orbiter will scan Mars’s atmosphere for gases that might indicate the presence of life, such as methane. On Earth, such gases are usually formed as a byproduct of living things.

In addition to looking for possible signs of life in the atmosphere, ExoMars 2016 will pave the way for an even more ambitious future mission. If all goes according to plan, Schiaparelli will be the first successful lander for either the ESA or Roscosmos. (Both have made previous, failed attempts to land a probe on Mars.) With this experience, the ESA and Roscosmos plan to send a large rover to the planet in 2018. This rover will continue to look for signs of past and present Martian life. It will carry a drill able to bore up to 8 feet (2 meters) below the surface. If life is hiding out on Mars, the ExoMars missions just might find it.

September 29, 2015

Mars. (NASA/JPL/Malin Space Science Systems)

The solar system just got a little bit wetter. Yesterday, scientists from the National Aeronautics and Space Administration (NASA) reported that water flows on Mars during warm seasons. They made the finding using a probe called the Mars Reconnaissance Orbiter (MRO).

Mars is the fourth planet from the sun. The planet is one of Earth’s “next-door neighbors” in space. Scientists have long suspected that water flowed on Mars in the distant past. Probes and rovers had found minerals on its surface that only form in the presence of water. Ice had also been discovered on Mars, both at the poles and other places on the planet.

In this illustration of our solar system, Mars is the fourth closest planet to the sun. Scientists have known for a while that Mars had liquid water on its surface at one time, but that Mars still has water at its surface today is an exciting discovery. (World Book illustration by Precision Graphics)

In August 2005, NASA launched the MRO, which arrived in orbit around Mars in March 2006. The craft was designed to study the planet’s structure and atmosphere and to identify potential landing sites for lander and rover missions. Scientists used the MRO’s instruments to observe mysterious dark streaks on Martian hillsides which appear to ebb and flow over time. The streaks darken in the warm season, when temperatures can exceed -10 °F (-23 °C).

The MRO revealed that these dark streaks were caused by liquid water saturated with salts. Salts lower the freezing point of water. This is why people in colder climates salt sidewalks in winter, and why oceans can stay liquid below the freezing point of pure water. In the warmer periods on Mars, the salts allow frozen water to melt and flow just under the surface of the hills. Some of the water wicks to the surface, forming dark spots.

The detection of liquid water on Mars will revitalize the search for current, as well as past, life on the planet. All known life needs liquid water to survive, so its presence on the Red Planet hints that life could possibly exist there today. Scientists are eager to continue the search for life, but also wary: liquid water on Mars will make it easier for organisms from Earth to colonize the planet. If probes land in these areas, bacteria could hitch a ride along with them and spread to the Martian surface, potentially changing or wiping out any native life that might exist there. Thus, space agencies may have to study such areas from a distance.

Other World Book articles

• Red Rover: Curiosity on Mars (a Special report)
• The Search for Water on Mars (a Special report)

March 27, 2015

This week, the rover Opportunity reached 26.2 total miles of travel on Mars, the Martian equivalent of an earthling marathon. The rover’s 0.00027-mile-per-hour average pace would not set any records on this planet, but Opportunity holds the record for the first (and only) marathon completed off Earth. Eleven years and two months is the time to beat.

NASA’s Opportunity rover appears in this computer-generated image. Credit: JPL/NASA

Opportunity is one of two identical probes sent to Mars in 2003 as part of the Mars Exploration Rover Mission to study the history of water on the planet. Engineers and scientists at the Jet Propulsion Laboratory designed and built the rovers for the United States National Aeronautics and Space Administration (NASA). Opportunity carries instruments created by teams of scientists and engineers from across the United States and Europe. The two rovers have helped scientists learn that water existed on the surface of Mars billions of years ago and that this water might have provided a suitable habitat for life.

Opportunity has traveled farther than any other off-Earth ground vehicle, including the piloted lunar rovers used in some of the Apollo missions. In July 2014, Opportunity broke the previous off-Earth record of 24.2 miles set in 1973 by the Soviet lunar rover Lunokhod 2.

Opportunity’s marathon shows just how tough and long-lived the little rover is. Opportunity and its twin Spirit were originally designed for 90-day missions. But they both continued to gather information on the surface of Mars long after that. Opportunity has powered through rugged terrain and age-related equipment problems to gather important information about the history of water on the Red Planet. This year, scientists worked to bypass a memory problem that caused the rover to “forget” the data it collected before sending it back to Earth.

Other World Book articles:

• Mars Pathfinder
• Mars Science Laboratory
• Astronomy (2004) (a Back in Time article)
• The Search for Water on Mars (a Special Report)

December 17, 2014

Evidence of life on Mars may have been discovered by NASA’s Curiosity Rover, scientists with the Curiosity team reported yesterday. One of the instruments on the robot has detected very strong spikes in the levels of methane gas measured at a vent in the planet’s Gale Crater. Scientists characterized these methane spikes as mysterious and not easily explained. Speaking at the American Geophysical Union convention in San Francisco, Sushil Atreya of the Curiosity team noted, “This temporary increase in methane—sharply up and then back down—tells us there must be some relatively localized source.” While the source is unknown, the NASA team speculates that it could be from very small, bacteria-like living organisms. On Earth, 95 percent of methane comes from microbial organisms. Atreya stated that other possible explanations include interaction of water and rocks or organic material left behind by meteors that is being degraded by the rays of the Sun. An earlier Curiosity test at Gale Crater suggested that water once flowed there billions of years ago.

NASA’s rover Curiosity discovered a spike in methane levels on Mars. (NASA/JPL-Caltech/MSSS)

NASA’s Curiosity Rover landed on Mars in 2012. A manned mission to Mars is planned for 2020.

Additional World Book articles:

• Red Rover: Curiosity on Mars (a special report)
• Space exploration 2012 (a Back in Time article)
• Space exploration 2013 (a Back in Time article)

December 9, 2014

Data from NASA’s Curiosity rover have revealed fascinating new details about the ancient geology of Mars, including the formation of Mount Sharp (also known as Aeolis Mons) and the abundance of surface water. The findings have also increased the likelihood that Earth may not have been the only planet in the solar system with primitive life billions of years ago.

Curiosity scientists reported that they think they have discovered why a 3-mile- (5-kilometer-) high mountain sits in the middle of Gale Crater, the impact crater where the rover landed in August 2012. Before Curiosity, scientists knew that Mount Sharp, like some mountains on Earth, consists of layer upon layer of sediment (layers of dirt, stone, and other materials laid down over many millions of years. But they did not know how Mount Sharp formed because, unlike Earth, Mars has not been shaped by plate tectonics. One theory was that the mountain formed from material that was thrown up as an asteroid or meteor crashed onto the surface there about 3.5 billion years ago. Another theory suggested that the mountain was “excavated” as sediments were eroded from around the peak. Studies made as Curiosity treks up the mountain now suggest that both wind and water were likely involved in the process.

Patterns of sedimentary deposits in Gale Crater suggests the crater held a lake more than 3 billion years ago, filling and drying in cycles that lasted tens of millions of years. (NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS)

Curiosity scientists think that Gale Crater experienced repeated wet and dry episodes that lasted for millions, or tens of millions, of years. During the wet episodes, rivers carrying water filled with sand and rock flowed over the crater’s rim to the floor, forming one large lake or even several smaller lakes. Over time, the sediments settled out of the water and hardened into layers that may have completely or partially filled the crater. During the dry episodes–when the water in the lakes evaporated–Martian winds sculpted the mountain by blowing away some of the sediment around the rim. Gradually, the mound in the center of the crater grew higher and higher.

Mount Sharp in Gale Crater likely formed from layers of sediment (yellow) carried by wind and by rivers flowing over the crater’s rim (above). The sediments then settled out in the center of the crater, forming rock (brown). Wind then eroded the sedimentary rock around the rim, forming Mount Shap. (NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS)

The existence of surface water–as well as underground water–on Mars for such a long period–perhaps 1 billion years–increases the chances that primitive life may have developed on the planet billions of years ago. In such a stable environment, which could have lasted for some 1 billion years, life could have arisen on the red planet some 3.8 billion years ago, as it did on Earth.

Additional World Book articles:

• Mars Pathfinder
• Phoenix [spacecraft]
• Space exploration (Probes to Mars)
• The Search for Water on Mars (a Special Report)

October 17, 2014

Numerous rovers and orbiting probes will break from their usual observations of Mars on Sunday to watch a comet flyby described by NASA officials as a once-in-a-million-year event. Comet Siding Spring–named for the Australian observatory where it was discovered in 2013–will pass within about 87,000 miles (139,500 kilometers) of the red planet. That’s less than half the distance between Earth and the moon. Siding Spring will zip by Mars at a speed of about 126,000 miles (56 kilometers) per hour at about 2:27 p.m., EDT.

Why are astronomers so excited?  For one, Siding Spring will be the first comet from the far-distant Oort cloud to be studied close up by spacecraft. For another, the comet is making its first-ever voyage through the inner solar system. That means it has never passed by sun and so has never been altered by the sun’s powerful heat and radiation. In other words, the comet looks much the same as it did 4.6 billion years ago, shortly after the formation of the solar system. “This is a cosmic science gift that could potentially keep on giving,” said John Grunsfeld of NASA’s Science Mission Directorate. “This particular comet … will provide a fresh source of clues to our solar system’s earliest days.”

Siding Spring, which has a nucleus (core) from 0.5 to 5 miles (0.8 to 8 kilometers) wide, is a well-traveled comet. Scientists believe it formed somewhere between the orbits of Jupiter and Neptune as the solar system was being born. At that time, many similar objects there were colliding and coming together to form the outer planets (Saturn, Jupiter, Uranus and Neptune). Siding Spring, however, apparently was caught by the gravitation pull of one of these planets and thrown out into the Oort cloud at the outer reaches of the solar system. For billions of years, the comet visited only the outer planets on its trips into the solar system. Then about one million years ago, it was jolted from its orbit–probably by a star passing by the Oort cloud–and started its voyage to the inner solar system.

When imaged by the Hubble Space Telescope on March 11, 2014, Comet Siding Spring was 353,000 miles (568,000 kilometers) from Earth. The coma (dust cloud) surrounding the comet’s nucleus (core) is about 12,000 miles (19,000 kilometers) wide. The comet will take about 1 million years to complete one orbit of the sun. (NASA, ESA, and J.-Y. Li [Planetary Science Institute])

“We can’t get to an Oort Cloud comet with our current rockets. These orbits are very long and extended, at very great velocities,” said Carey Lisse, a senior astrophysicist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “So this comet is coming to us. It’s a free flyby, if you will, and that’s a very fantastic event for us to study.”

Watching for the comet–and observing its effects on the Martian atmosphere–will be various Mars orbiters, including the Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Atmosphere and Volatile Evolution craft. Other observers will be the Hubble, Spitzer, Kepler, and Chandra space telescope. Scientists are particularly interested in what the Mars rovers Curiosity and Opportunity make of the comet. If the Martian atmosphere isn’t too dusty, they could provide the first images of a comet from another planet.

Additional World Book articles:

• Exploring the Outer Solar System (a Special Report)
• When Worlds and Comets Collide (a Special Report)