Five Things About NASA's Mars Curiosity Rover

Mars Science Laboratory, aka Curiosity, is part of NASA's Mars Exploration Program, a long-term program of robotic exploration of the Red Planet. The mission is scheduled to launch from Cape Canaveral, Fla., in late 2011, and arrive at an intriguing region of Mars in August 2012.

The goal of Curiosity, a rolling laboratory, is to assess whether Mars ever had an environment capable of supporting microbial life and conditions favorable for preserving clues about life, if it existed. This will help us better understand whether life could have existed on the Red Planet and, if so, where we might look for it in the future.

1. How Big Is It?: The Mini Cooper-sized rover is much bigger than its rover predecessors, Spirit, Opportunity and Pathfinder. Curiosity is twice as long (about 2.8 meters, or 9 feet) and four times as heavy as Spirit and Opportunity, which landed in 2004. Pathfinder, about the size of a microwave oven, landed in 1997.
2. Landing--Where and How: In November 2008, possible landing sites were narrowed to four finalists, all linked to ancient wet conditions. NASA will select a site believed to be among the most likely places to hold a geological record of a favorable environment for life. The site must also meet safe-landing criteria. The landing system is similar to a sky crane heavy-lift helicopter. After a parachute slows the rover's descent toward Mars, a rocket-powered backpack will lower the rover on a tether during the final moments before landing. This method allows landing a very large, heavy rover on Mars (instead of the airbag landing systems of previous Mars rovers). Other innovations enable a landing within a smaller target area than previous Mars missions.
   
   
3. Toolkit: Curiosity will use 10 science instruments to examine rocks, soil and the atmosphere. A laser will vaporize patches of rock from a distance, and another instrument will search for organic compounds. Other instruments include mast-mounted cameras to study targets from a distance, arm-mounted instruments to study targets they touch, and deck-mounted analytical instruments to determine the composition of rock and soil samples acquired with a powdering drill and a scoop.
   
   
4. Big Wheels: Each of Curiosity's six wheels has an independent drive motor. The two front and two rear wheels also have individual steering motors. This steering allows the rover to make 360-degree turns in-place on the Mars surface. The wheels' diameter is double the wheel diameter on Spirit and Opportunity, which will help Curiosity roll over obstacles up to 75 centimeters (30 inches) high.
   
   
5. Rover Power: A nuclear battery will enable Curiosity to operate year-round and farther from the equator than would be possible with only solar power.
   

Source NASA

NASA Data Track Seasonal Pollution Changes Over India

Data from the Multi-angle Imaging Spectroradiometer (MISR) instrument on NASA's Terra spacecraft have been used in a groundbreaking new university study that examines the concentration, distribution and composition of aerosol pollution over the Indian subcontinent. The study documents the region's very high levels of natural and human-produced pollutants, and uncovered surprising seasonal shifts in the source of the pollution.

Larry Di Girolamo and postdoctoral scientist Sagnik Dey of the University of Illinois, Champaign, used a decade's worth of MISR data to comprehensively analyze aerosol pollution over the Indian subcontinent. This densely populated region has poor air quality and lacks on-the-ground pollution monitoring sites. The study was published recently in the Journal of Geophysical Research.

Aerosols — tiny particles suspended in the air — are produced both by natural sources, such as dust and pollen carried on the wind, and by human activities, such as soot and other hydrocarbons released from the burning of fossil fuels. They can affect the environment and human health, causing a range of respiratory problems. Aerosol pollution levels can be measured on the ground, but only the most developed countries have widespread sensor data.

Since standard satellite imaging cannot measure aerosols over land, Di Girolamo and Dey used NASA's MISR, developed and managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. MISR's unique multi-view design allows researchers to differentiate surface variability from the atmosphere so they can observe and quantitatively measure particles in the air.

MISR not only measures the amount of aerosols, but can also distinguish between natural and human-produced particles.
The scientists found very high levels of both natural and human-produced aerosol pollutants. The level of atmospheric pollution across most of the country was two to five times higher than World Health Organization guidelines.

But the study also revealed some surprising trends. For example, the researchers noticed consistent seasonal shifts in human-produced versus natural aerosols. Before monsoon season begins, the winds over the Indian subcontinent shift, blowing inland instead of out to sea. These winds carry immense amounts of dust from Africa and the Arabian Peninsula to India, degrading air quality.

"Just before the rains come, the air gets really polluted, and for a long time everyone blamed the dust," Di Girolamo said, "but MISR has shown that not only is there an influx of dust, there's also a massive buildup of man-made pollutants that's hidden within the dust."

During monsoon season, rains wash some of the dust and soot from the air, but other human-produced pollutants continue to build up. After monsoon season, dust transport is reduced, but human-produced pollutant levels skyrocket, as biomass burning and the use of diesel-fueled transportation soar. During winter, seaward-blowing breezes disperse all the pollutants across the subcontinent and out to sea, where they remain until the pre-monsoon winds blow again.

"We desperately needed these observations to help validate our atmospheric models," said Di Girolamo. "We're finding that in a complex area like India, we have a long way to go. But these observations help give us some guidance."
As MISR continues to collect worldwide aerosol data, Di Girolamo says atmospheric scientists will continue to refine models for India and other areas and begin to propose new regulatory measures. The MISR data may also reveal trends in aerosol concentration over time, which can be compared with climate and health data.

For further information, read the complete University of Illinois news release at: http://www.news.illinois.edu/news/10/0907aerosol_DiGirolamo.html .
For more on MISR, visit: http://www-misr.jpl.nasa.gov/ .
Source NASA

NASA's HIRAD Instrument to Provide Unique View of Hurricane Wind Speeds

taken by the crew of the International Space Station

Scientists examine the inner workings of HIRAD. HIRAD is small, lightweight, relatively inexpensive, and has no moving parts, giving it a big advantage as it flies through hurricanes.

 

NASA researchers are furiously preparing for late summer when they will fly a series of unique hurricane instruments, including a brand new instrument that will take two-dimensional wind speed measurements over some of the world's fiercest storms.

The instrument will be part of a six-week NASA mission to study tropical cyclones beginning Aug. 15. The Genesis and Rapid Intensification Processes mission, or GRIP, will study the creation and rapid intensification of hurricanes. The campaign involves three planes with 15 instruments that will work together to create the most complete view of hurricanes to date.

HIRAD is mounted for testing in an anechoic chamber, a chamber outfitted with foam spikes to eliminate all ambient microwaves so that scientists can properly test the instrument.

Scientists and engineers at NASA's Marshall Space Flight Center in Huntsville, Ala. along with their partners from across the country have built the Hurricane Imaging Radiometer, HIRAD for short, to contribute to the effort. HIRAD will help determine the strength and structure of hurricanes by looking at wind speeds deep within the storm. This August and September, HIRAD will fly in the belly of a WB-57 airplane at about 60,000 feet, about twice the altitude of a commercial airliner.

Researchers across the world, including scientists at National Oceanic and Atmospheric Administration (NOAA) who have joined in HIRAD's development, hope it will provide key insight into some of nature's most puzzling questions. By allowing researchers to measure wind speeds inside the storm, HIRAD will give scientists some clues about why hurricanes behave like they do.

"The main thing we hope to do is improve the forecasts of intensity of a hurricane. Will it intensify? Will it maintain its intensity? Will it weaken? That's the hardest part of predicting hurricanes," says Dr. Tim Miller, HIRAD principal investigator and atmospheric scientist at the Marshall Center. "Of course, all science is incremental, but HIRAD hopes to make a fairly strong improvement to such forecasting."

Better predictions mean better preparations. Better predictions help people figure out when to evacuate, and when not to, as poor predictions and false alarms cost millions of dollars. More importantly, accurate forecasting builds credibility with the public so that they take evacuation warnings seriously.

HIRAD collects wind speed data by using a large antenna to measure the activity on the ocean's surface. The antenna is similar to a common radio antenna, but instead of detecting radio waves from a manufactured transmitter, it measures microwaves emitted from the ocean surface. As winds move across the surface of the sea they generate white, frothy foam. That sea foam causes the ocean surface to emit increasingly large amounts of microwave radiation, similar to the type of energy emitted by a typical home microwave oven. HIRAD captures that microwave energy and, in doing so, allows scientists to deduce how powerfully the wind is blowing.

Using the information provided by HIRAD, along with lots of other data, scientists can construct a more complete and detailed representation of the hurricane.

"We get lots of little pieces of information to figure out what's happening inside the storm," Miller explains. "We combine HIRAD's data with information from weather balloons, weather satellites and other instruments flying in the hurricane campaign, we put it all together, and we can potentially predict how a hurricane will behave."

HIRAD, measures not only directly under the plane, but also out to each side. "You can imagine if we just got a single line of measurements, we wouldn't see the full image of the wind speed. But because of HIRAD's design, we get the full two-dimensional picture," explains Miller. "Even though we're only measuring the ocean’s surface, computer models can take that information and use it to help develop a three-dimensional structure of the hurricane."

Designing and building HIRAD hasn't been easy. Engineers had to find the perfect materials to insulate the antenna elements and form the elements into the precise sizes and shapes that capture microwaves at the exact frequencies required. Fortunately, the HIRAD team's hard work is paying off. A successful flight in early 2010 revealed HIRAD is prepared to fly in NASA's upcoming study of hurricanes. Because a single flaw could mean failure, the HIRAD team works daily to keep the instrument in good shape and to reduce the risk of any problems that might arise.

During the hurricane study, HIRAD and the other instruments will likely fly several times over major storms in the Gulf of Mexico and Atlantic. Each mission will last roughly six hours, and Miller and his team from Marshall, NOAA, and the University of Michigan will monitor incoming data from the ground. Once the plane lands, the team will pull the remaining data from the plane and began their analysis.

For Miller, it's a fascinating challenge.

"I've always been interested in science. I grew up on a farm in Ohio, always saw the weather changing, and couldn't help but wonder why," he chuckles. "Hurricanes are big and complex, and a pretty challenging problem for someone who likes to understand how things work, why they do what they do."

After this fall's study, HIRAD will continue to fly in hurricane campaigns. The instrument has already been drafted for use in the Hurricane and Severe Storm Sentinel study that starts in 2011 and lasts for five years. But for now, Miller looks forward in anticipation to HIRAD's virgin flight this August.

"We're approaching it with enthusiasm and caution. If the storms are there, we need to get as much data from them as we can," he says. "Our fingers are crossed." If all goes well, HIRAD will have completed its first mission by late September. Once the flight is over, researchers will start to pore over and analyze the data. It will require countless hours of work, but the potential payoff is enormous.

The instrument will fly on a WB-57 based at Ellington Field in Houston. The WB-57 is one of the few aircraft capable of operating at 60,000 feet, an altitude so high that the pilots have to wear special pressurized suits to withstand the harsh conditions

For now, Miller and his team are looking forward to the HIRAD's voyage with excitement and anticipation. Hopefully, HIRAD's journey will put NASA researchers one step closer to understanding some of the most powerful storms in the world.

For more information about the GRIP field experiment, visit:


http://www.nasa.gov/grip

 

 

Source NASA

Chandra Finds Evidence for Stellar Cannibalism

Evidence that a star has recently engulfed a companion star or a giant planet has been found using NASA's Chandra X-ray Observatory. The likely existence of such a "cannibal" star provides new insight into how stars and the planets around them may interact as they age.

The star in question, known as BP Piscium (BP Psc), appears to be a more evolved version of our Sun, but with a dusty and gaseous disk surrounding it. A pair of jets several light years long blasting out of the system in opposite directions has also been seen in optical data. While the disk and jets are characteristics of a very young star, several clues -- including the new results from Chandra -- suggest that BP Psc is not what it originally appeared to be.

Instead, astronomers have suggested that BP Psc is an old star in its so-called red giant phase. And, rather than being hallmarks of its youth, the disk and jets are, in fact, remnants of a recent and catastrophic interaction whereby a nearby star or giant planet was consumed by BP Psc.

When stars like the Sun begin to run of nuclear fuel, they expand and shed their outer layers. Our Sun, for example, is expected to swell so that it nearly reaches or possibly engulfs Earth, as it becomes a red giant star.

"It appears that BP Psc represents a star-eat-star Universe, or maybe a star-eat-planet one," said Joel Kastner of the Rochester Institute of Technology, who led the Chandra study. "Either way, it just shows it's not always friendly out there."

Several pieces of information have led astronomers to rethink how old BP Psc might be. First, BP Psc is not located near any star-forming cloud, and there are no other known young stars in its immediate vicinity. Secondly, in common with most elderly stars, its atmosphere contains only a small amount of lithium. Thirdly, its surface gravity appears to be too weak for a young star and instead matches up with one of an old red giant.

Chandra adds to this story. Young, low-mass stars are brighter than most other stars in X-rays, and so X-ray observations can be used as a sign of how old a star may be. Chandra does detect X-rays from BP Psc, but at a rate that is too low to be from a young star. Instead, the X-ray emission rate measured for BP Psc is consistent with that of rapidly rotating giant stars.

The spectrum of the X-ray emission -- that is how the amount of X-rays changes with wavelength -- is consistent with flares occurring on the surface of the star, or with interactions between the star and the disk surrounding it. The magnetic activity of the star itself might be generated by a dynamo caused by its rapid rotation. This rapid rotation can be caused by the engulfment process.

"It seems that BP Psc has been energized by its meal," said co-author Rodolfo (Rudy) Montez Jr., also from the Rochester Institute of Technology.

The star's surface is obscured throughout the visible and near-infrared bands, so the Chandra observation represents the first detection at any wavelength of BP Psc itself.

"BP Psc shows us that stars like our Sun may live quietly for billions of years," said co-author David Rodriguez from UCLA, "but when they go, they just might take a star or planet or two with them."

Although any close-in planets were presumably devastated when BP Psc turned into a giant star, a second round of planet formation might be occurring in the surrounding disk, hundreds of millions of years after the first round. A new paper using observations with the Spitzer Space Telescope has reported possible evidence for a giant planet in the disk surrounding BP Psc. This might be a newly formed planet or one that was part of the original planetary system.

"Exactly how stars might engulf other stars or planets is a hot topic in astrophysics today," said Kastner. "We have many important details that we still need to work out, so objects like BP Psc are really exciting to find."

These results appeared in The Astrophysical Journal Letters. Other co-authors on the study were Nicolas Grosso of the University of Strasbourg, Ben Zuckerman from UCLA, Marshall Perrin from the Space Telescope Science Institute, Thierry Forveille of the Grenoble Astrophysics Laboratory in France and James Graham from University of California, Berkeley.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

More information, including images and other multimedia, can be found at:


http://chandra.harvard.edu

 

Source NASA

A Snapshot of Sea Ice

The Arctic Ocean is covered by a dynamic layer of sea ice that grows each winter and shrinks each summer, reaching its yearly minimum size each fall. While the 2010 minimum remains to be seen, NASA's Aqua satellite captured this snapshot on Sept. 3.

How does the Aqua satellite "see" sea ice? Microwaves. Everything on Earth’s surface -- including people -- emits microwave radiation, the properties of which vary with the emitter, thereby allowing the AMSR-E microwave sensor on Aqua to map the planet.

Ice emits more microwave radiation than water, making regions of the ocean with floating ice appear much brighter than the open ocean to the AMSR-E sensor. This difference allows the satellite to capture a sea ice record year-round, through cloud cover and the months of polar night. Continuous records are important because sea ice is dynamic. Besides melting and freezing, the ice moves with wind and currents which can cause it to split or pile up.

"The data from AMSR-E and other NASA satellites are critical for understanding the coupling between sea ice and the ocean and atmosphere," said Tom Wagner, Cryosphere program manager at NASA Headquarters in Washington. "It’s important for us to understand these connections to improve our predictive models of how the planet will change."

The Arctic sea ice is a major factor in the global climate system. The ice cools the planet by reflecting sunlight back into space. It also helps drive ocean circulation by converting the warm Pacific water that flows into the Arctic into the cold, saltier water that empties into the Atlantic. The sea ice also fundamentally shapes the Arctic; defining the organisms that make up its ecosystem and keeping heat from the ocean from melting the frozen tundra.

In fall 2009, Arctic sea ice reached its minimum extent on about Sept. 12, and was the third lowest since satellite microwave measurements were first made in 1979. Researchers are interested in year-to-year changes, which can be highly variable, so that scientists need many years, even decades, of data to examine long-term trends. Notably, all of the major minimums have occurred in the last decade, consistent with other NASA research, which shows January 2000 to December 2009 was the warmest decade on record.

As the sea ice nears the 2010 minimum later this month, look for images and analysis from NASA and the National Snow and Ice Data Center, in Boulder, Colo.

Source NASA

Deadly Tides Mean Early Exit for Hot Jupiters

Bad news for planet hunters: most of the "hot Jupiters" that astronomers have been searching for in star clusters were likely destroyed long ago by their stars. In a paper accepted for publication by the Astrophysical Journal, John Debes and Brian Jackson of NASA's Goddard Space Flight Center in Greenbelt, Md., offer this new explanation for why no transiting planets (planets that pass in front of their stars and temporarily block some of the light) have been found yet in star clusters. The researchers also predict that the planet hunting being done by the Kepler mission is more likely to succeed in younger star clusters than older ones.

"Planets are elusive creatures," says Jackson, a NASA Postdoctoral Program fellow at Goddard, "and we found another reason that they're elusive."

When astronomers began to search for planets in star-packed globular clusters about 10 years ago, they hoped to find many new worlds. One survey of the cluster called 47 Tucanae (47 Tuc), for example, was expected to find at least a dozen planets among the roughly 34,000 candidate stars. "They looked at so many stars, people thought for sure they would find some planets," says Debes, a NASA Postdoctoral Program fellow at Goddard. "But they didn't."

More than 450 exoplanets (short for "extrasolar planets," or planets outside our solar system) have been found, but "most of them have been detected around single stars," Debes notes.

"Globular clusters turn out to be rough neighborhoods for planets," explains Jackson, "because there are lots of stars around to beat up on them and not much for them to eat." The high density of stars in these clusters means that planets can be kicked out of their solar systems by nearby stars. In addition, the globular clusters surveyed so far have been rather poor in metals (elements heavier than hydrogen and helium), which are the raw materials for making planets; this is known as low metallicity.

Debes and Jackson propose that hot Jupiters—large planets that are at least 3 to 4 times closer to their host stars than Mercury is to our sun—are quickly destroyed. In these cramped orbits, the gravitational pull of the planet on the star can create a tide—that is, a bulge—on the star. As the planet orbits, the bulge on the star points a little bit behind the planet and essentially pulls against it; this drag reduces the energy of the planet's orbit, and the planet moves a little closer to the star. Then the bulge on the star gets bigger and saps even more energy from the planet's orbit. This continues for billions of years until the planet crashes into the star or is torn apart by the star's gravity, according to Jackson's model of tidal orbital decay.

"The last moments for these planets can be pretty dramatic, as their atmospheres are ripped away by their stars' gravity," says Jackson. "It has even been suggested recently the hot Jupiter called WASP-12B is close enough to its star that it is currently being destroyed."

Debes and Jackson modeled what would have happened in 47 Tuc if the tidal effect were unleashed on hot Jupiters. They recreated the range of masses and sizes of the stars in that cluster and simulated a likely arrangement of planets. Then they let the stars' tides go to work on the close-in planets. The model predicted that so many of these planets would be destroyed, the survey would come up empty-handed. "Our model shows that you don't need to consider metallicity to explain the survey results," says Debes, "though this and other effects will also reduce the number of planets."

Ron Gilliland, who is at the Space Telescope Science Institute in Baltimore and participated in the 47 Tuc survey, says, "This analysis of tidal interactions of planets and their host stars provides another potentially good explanation—in addition to the strong correlation between metallicity and the presence of planets—of why we failed to detect exoplanets in 47 Tuc."

In general, Debes and Jackson's model predicts that one-third of the hot Jupiters will be destroyed by the time a cluster is a billion years old, which is still juvenile compared to our solar system (about 4-1/2 billion years old). 47 Tuc has recently been estimated to be more than 11 billion years old. At that age, the researchers expect more than 96% of the hot Jupiters to be gone.

The Kepler mission, which is searching for hot Jupiters and smaller, Earth-like planets, gives Debes and Jackson a good chance to test their model. Kepler will survey four open clusters—groups of stars that are not as dense as globular clusters—ranging from less than half a billion to nearly 8 billion years old, and all of the clusters have enough raw materials to form significant numbers of planets, Debes notes. If tidal orbital decay is occurring, Debes and Jackson predict, Kepler could find up to three times more Jupiter-sized planets in the youngest cluster than in the oldest one. (An exact number depends on the brightness of the stars, the planets' distance from the stars, and other conditions.)

"If we do find planets in those clusters with Kepler," says Gilliland, a Kepler co-investigator, "looking at the correlations with age and metallicity will be interesting for shaping our understanding of the formation of planets, as well as their continued existence after they are formed."

If the tidal orbital decay model proves right, Debes adds, planet hunting in clusters may become even harder. "The big, obvious planets may be gone, so we'll have to look for smaller, more distant planets," he explains. "That means we will have to look for a much longer time at large numbers of stars and use instruments that are sensitive enough to detect these fainter planets."

The Kepler mission is managed by NASA's Ames Research Center, Moffett Field, Calif., for the Science Mission Directorate at NASA Headquarters in Washington.

Source NASA

NASA Data Shed New Light About Water and Volcanoes on Mars

PASADENA, Calif. -- Data from NASA's Phoenix Mars Lander suggest liquid water has interacted with the Martian surface throughout the planet's history and into modern times. The research also provides new evidence that volcanic activity has persisted on the Red Planet into geologically recent times, several million years ago.

Although the lander, which arrived on Mars on May 25, 2008, is no longer operating, NASA scientists continue to analyze data gathered from that mission. These recent findings are based on data about the planet's carbon dioxide, which makes up about 95 percent of the Martian atmosphere.

"Atmospheric carbon dioxide is like a chemical spy," said Paul Niles, a space scientist at NASA's Johnson Space Center in Houston. "It infiltrates every part of the surface of Mars and can indicate the presence of water and its history."
Phoenix precisely measured isotopes of carbon and oxygen in the carbon dioxide of the Martian atmosphere. Isotopes are variants of the same element with different atomic weights. Niles is lead author of a paper about the findings published in Thursday's online edition of the journal Science. The paper explains the ratios of stable isotopes and their implications for the history of Martian water and volcanoes.

"Isotopes can be used as a chemical signature that can tell us where something came from, and what kinds of events it has experienced," Niles said.
This chemical signature suggests that liquid water primarily existed at temperatures near freezing and that hydrothermal systems similar to Yellowstone's hot springs have been rare throughout the planet's past. Measurements concerning carbon dioxide showed Mars is a much more active planet than previously thought. The results imply Mars has replenished its atmospheric carbon dioxide relatively recently, and the carbon dioxide has reacted with liquid water present on the surface.

Measurements were performed by an instrument on Phoenix called the Evolved Gas Analyzer. The instrument was capable of doing more accurate analysis of carbon dioxide than similar instruments on NASA's Viking landers in the 1970s. The Viking Program provided the only previous Mars isotope data sent back to Earth.

The low gravity and lack of a magnetic field on Mars mean that as carbon dioxide accumulates in the atmosphere, it will be lost to space. This process favors loss of a lighter isotope named carbon-12 compared to carbon-13. If Martian carbon dioxide had experienced only this process of atmospheric loss without some additional process replenishing carbon-12, the ratio of carbon-13 to carbon-12 would be much higher than what Phoenix measured. This suggests the Martian atmosphere recently has been replenished with carbon dioxide emitted from volcanoes, and volcanism has been an active process in Mars' recent past.

However, a volcanic signature is not present in the proportions of two other isotopes, oxygen-18 and oxygen-16, found in Martian carbon dioxide. The finding suggests the carbon dioxide has reacted with liquid water, which enriched the oxygen in carbon dioxide with the heavier oxygen-18.

Niles and his team theorize this oxygen isotopic signature indicates liquid water has been present on the Martian surface recently enough and abundantly enough to affect the composition of the current atmosphere. The findings do not reveal specific locations or dates of liquid water and volcanic vents, but recent occurrences of those conditions provide the best explanations for the isotope proportions.

The Phoenix mission was led by principal investigator Peter H. Smith of the University of Arizona in Tucson, with project management at NASA's Jet Propulsion Laboratory in Pasadena, Calif. JPL is a division of the California Institute of Techology in Pasadena. The University of Arizona provided the lander's Thermal and Evolved Gas Analyzer.

For more information about the Phoenix mission, visit http://www.nasa.gov/phoenix .

source NASA