(Above) Images from NASA’s Galaxy Evolution Explorer spacecraft and the Cerro Tololo Inter-American Observatory in Chile.

For decades, astronomers have gone about their business of studying the cosmos with the assumption that stars of certain sizes form in certain quantities. Like grocery stores selling melons alone, and blueberries in bags of dozens or more, the universe was thought to create stars in specific bundles. In other words, the proportion of small to big stars was thought to be fixed. For every star 20 or more times as massive as the sun, for example, there should be 500 stars with the sun’s mass or less.

This belief, based on years of research, has been tipped on its side with new data from NASA’s Galaxy Evolution Explorer. The ultraviolet telescope has found proof that small stars come in even bigger bundles than previously believed; for example, in some places in the cosmos, about 2,000 low-mass stars may form for each massive star. The little stars were there all along but masked by massive, brighter stars.

“What this paper is showing is that some of the standard assumptions that we’ve had – that the brightest stars tell you about the whole population of stars – this doesn’t seem to work, at least not in a constant way,” said Gerhardt R. Meurer, principal investigator on the study and a research scientist at Johns Hopkins University, Baltimore, Md.

Astronomers have long known that many stars are too dim to be seen in the glare of their brighter, more massive counterparts. Though the smaller, lighter stars outnumber the big ones, they are harder to see. Going back to a grocery story analogy, the melons grab your eyes, even though the total weight of the blueberries may be more.

Beginning in the 1950s, astronomers came up with a method for counting all the stars in a region, even the ones they couldn’t detect. They devised a sort of stellar budget, an equation called the “stellar initial mass function,” to estimate the total number of stars in an area of the sky based on the light from only the brightest and most massive. For every large star formed, a set number of smaller ones were thought to have been created regardless of where the stars sat in the universe.

“We tried to understand properties of galaxies and their mass by looking at the light we can see,” Meurer said.

But this common assumption has been leading astronomers astray, said Meurer, especially in galaxies that are intrinsically small and faint.

To understand the problem, imagine trying to estimate the population on Earth by observing light emitted at night. Looking from above toward North America or Europe, the regions where more people live light up like signposts. Los Angeles, for example, is easily visible to a scientist working on the International Space Station. However, if this method were applied to regions where people have limited electricity, populations would be starkly underestimated, for example in some sections of Africa.

The same can be said of galaxies, whose speckles of light in the dark of space can be misleading. Meurer and his team used ultraviolet images from the Galaxy Evolution Explorer and carefully filtered red-light images from telescopes at the Cerro Tololo Inter-American Observatory in Chile to show that many galaxies do not form a lot of massive stars, yet still have plenty of lower-mass counterparts. The ultraviolet images are sensitive to somewhat small stars three times or more massive than the sun, while the filtered optical images are only sensitive to the largest stars with 20 or more times the mass of the sun.

The effects are particularly important in parts of the universe where stars are spread out over a larger volume — the rural Africa of the cosmos. There could be about four times as many stars in these regions than previously estimated.

“Especially in these galaxies that seem small and piddling, there can be a lot more mass in lower mass stars than we had previously expected from what we could see from the brightest, youngest stars,” Meurer said. “But we can now reduce these errors using satellites like the Galaxy Evolution Explorer.”

This research was published in the April 10, 2009, issue of Astrophysical Journal.

The Planck space telescope has begun to collect light left over from the Big Bang explosion that created our universe.

The mission, which is led by the European Space Agency with important participation from NASA, will help answer the most fundamental of questions: How did space itself pop into existence and expand to become the universe we live in today? The answer is hidden in ancient light, called the cosmic microwave background, which has traveled more than 13 billion years to reach us. Planck will measure tiny variations in this light with the best precision to date.

The mission officially started collecting science data on Aug. 13, as part of a test period. If all goes as planned, these observations will be the first of 15 or more months of data gathered from two full-sky scans. Science results are expected in about three years.

Read about NASA and JPL’s role in the mission at http://www.nasa.gov/mission_pages/planck/overview.html
More information about the mission is also online at http://www.esa.int/SPECIALS/Planck/index.html .

A deployable satellite reflector and boom assembly from Northrop Grumman Corporation will help NASA’s Jet Propulsion Laboratory (JPL) map soil moisture and the freezing and thawing cycles globally with unprecedented accuracy, resolution and coverage.

The company’s AstroMesh-Lite configuration deployable reflector will be used on JPL’s Soil Moisture Active/Passive (SMAP) mission targeted for launch in 2014. This mission will use a combined radiometer and high-resolution radar to make direct measurements of soil moisture and freeze/thaw state to aid understanding of regional and global water cycles, ecosystem productivity, and the processes that link water, energy and carbon cycles.

“The SMAP mission is critical to understanding the health of the Earth’s ecology. We are proud of our successful history of teaming with JPL on multiple planetary missions going back as far as Voyager to the outer planets and more recently to Mars,” said Richard Nelson, general manager of Astro Aerospace, a Carpinteria-based strategic business unit of Northrop Grumman’s Aerospace Systems sector. The unit specializes in advanced deployable structures for space applications.

AstroMesh-Lite is a member of Northrop Grumman’s flight proven AstroMesh “Perimeter Truss” reflector line, optimized for the three- to eight-meter aperture size. For the SMAP mission, its approximately six-meter aperture will provide high-resolution data to enable improvements to weather and climate forecasts, flood prediction and drought monitoring, and measurement of net carbon dioxide uptake in forested regions.

“Astro Aerospace has a stellar history of 100 percent mission deployment success,” noted Chris Yamada, general manager for Northrop Grumman Aerospace Systems’ strategic business units. “The AstroMesh family is the only deployable mesh reflector with a perfect on-orbit deployment record — no failures, and no anomalies. Astro’s selection to the SMAP team is a tribute to its continuing commitment to assure mission success.”

The Opportunity rover has eyed an odd-shaped, dark rock, about 2 feet across on the surface of Mars, which may be a meteorite.

Scientists will be testing the rock with the particle X-ray spectrometer to get composition measurements and to confirm if indeed it is a meteorite.

The team spotted the rock called “Block Island,” on July 18, 2009, in the opposite direction from which it was driving. The rover then backtracked some 250 meters (820 feet) to study it closer.

Scientists will be testing the rock with the alpha particle X-ray spectrometer to get composition measurements and to confirm if indeed it is a meteorite.

NASA’s Jet Propulsion Laboratory is introducing a new Web site that will provide a centralized resource for information on near-Earth objects – those asteroids and comets that can approach Earth. The “Asteroid Watch” site also contains links for the interested public to sign up for NASA’s new asteroid widget and Twitter account.

“Most people have a fascination with near-Earth objects,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL. “And I have to agree with them. I have studied them for over three decades and I find them to be scientifically fascinating, and a few are potentially hazardous to Earth. The goal of our Web site is to provide the public with the most up-to-date and accurate information on these intriguing objects.”

The new Asteroid Watch site is online at http://www.jpl.nasa.gov/asteroidwatch

It provides information on NASA’s missions to study comets, asteroids and near-Earth objects, and also provides the basic facts and the very latest in science and research on these objects. News about near-Earth object discoveries and Earth flybys will be available and made accessible on the site via a downloadable widget and RSS feed. And for those who want to learn about their space rocks on the go, a Twitter feed is offered. “Asteroid Watch” also contains a link to JPL’s more technical Near-Earth Objects Web site, where many scientists and researchers studying near-Earth objects go for information.

“This innovative new Web application gives the public an unprecedented look at what’s going on in near-Earth space,” said Lindley Johnson, program executive for the Near-Earth Objects Observation program at NASA Headquarters in Washington.

NASA supports surveys that detect and track asteroids and comets passing close to Earth. The Near-Earth Object Observation Program, commonly called “Spaceguard,” also plots the orbits of these objects to determine if any could be potentially hazardous to our planet.

(Above) This image shows a large impact on Jupiter’s south polar region captured on July 20, 2009, by NASA’s Infrared Telescope Facility in Mauna Kea, Hawaii.

Scientists have found evidence that another object has bombarded Jupiter, exactly 15 years after the first impacts by the comet Shoemaker-Levy 9.

Following up on a tip by an amateur astronomer, Anthony Wesley of Australia, that a new dark “scar” had suddenly appeared on Jupiter, this morning between 3 and 9 a.m. PDT (6 a.m. and noon EDT) scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., using NASA’s Infrared Telescope Facility at the summit of Mauna Kea, Hawaii, gathered evidence indicating an impact.

New infrared images show the likely impact point was near the south polar region, with a visibly dark “scar” and bright upwelling particles in the upper atmosphere detected in near-infrared wavelengths, and a warming of the upper troposphere with possible extra emission from ammonia gas detected at mid-infrared wavelengths.

“We were extremely lucky to be seeing Jupiter at exactly the right time, the right hour, the right side of Jupiter to witness the event. We couldn’t have planned it better,” said Glenn Orton, a scientist at JPL.

Orton and his team of astronomers kicked into gear early in the morning and haven’t stopped tracking the planet. They are downloading data now and are working to get additional observing time on this and other telescopes.

This image was taken at 1.65 microns, a wavelength sensitive to sunlight reflected from high in Jupiter’s atmosphere, and it shows both the bright center of the scar (bottom left) and the debris to its northwest (upper left).

“It could be the impact of a comet, but we don’t know for sure yet,” said Orton. “It’s been a whirlwind of a day, and this on the anniversary of the Shoemaker-Levy 9 and Apollo anniversaries is amazing.”

Shoemaker-Levy 9 was a comet that had been seen to break into many pieces before the pieces hit Jupiter in 1994.

Leigh Fletcher, a NASA postdoctoral fellow at JPL who worked with Orton during these latest observations said, “Given the rarity of these events, it’s extremely exciting to be involved in these observations. These are the most exciting observations I’ve seen in my five years of observing the outer planets!”

The observations were made possible in large measure by the extraordinary efforts of the Infrared Telescope Facility staff, including telescope operator William Golisch, who adroitly moved three instruments in and out of the field during the short time the scar was visible on the planet, providing the wide wavelength coverage.

(Above) While the panoramic camera (Pancam) on NASA’s Mars Exploration Rover Spirit was taking exposures with different color filters during the 1,919th Martian day of the rover’s mission (May 27, 2009), dust devils moved across the field of view.

Scientists have combined a trio of shots taken seconds apart through different colored filters to create a special-effects portrait of a moving dust devil on Mars.

The panoramic camera on NASA’s Mars Exploration Rover Spirit was taking exposures through different filters during the 1,919th Martian day of Spirit’s mission (May 27, 2009) as part of constructing a large color panorama. Three westward shots, with several seconds intervening between them, caught a whirlwind in motion. A composite image combining the three exposures to make a color image of the Martian ground shows the dust devil in different colors, according to where it was on the horizon when each exposure was taken.

Dust devils occur on both Mars and on Earth when solar energy heats the surface, resulting in a layer of warm air just above the surface. Since the warmed air is less dense than the cooler atmosphere above it, it rises, making a swirling thermal plume that picks up the fine dust from the surface and carries it up into the atmosphere. This plume of dust moves with the local wind.

More than 650 dust devils have been recorded by Spirit since its operations began in 2004. The mission is currently in its third season of dust devils on Mars, which typically begin in Martian spring.

(Above) The finished heat shield for NASA’s Mars Science Laboratory, with a diameter of 4.5 meters (14 feet, 9 inches), is the largest ever built for descending through the atmosphere of any planet. This image shows the heat shield and a spacecraft worker at Lockheed Martin Space Systems, Denver, which built and tested the heat shield.

Lockheed Martin completed production and testing of the heatshield for NASA’s Mars Science Laboratory (MSL). The heatshield is half of the large and sophisticated two-part aeroshell that will encapsulate and protect the Curiosity rover during its deep space cruise to Mars, and from the intense heat and friction that will be generated as the system descends through the Martian atmosphere.

In October 2008, Lockheed Martin delivered the other half of the aeroshell, the backshell, to NASA’s Jet Propulsion Laboratory in Pasadena, Calif. where it is being integrated with other flight systems. The heatshield will be stored at Lockheed Martin facilities near Denver, Colo. until early 2011 when it will be shipped to Kennedy Space Center.

The aeroshell/heatshield is the largest ever built to be flown at 4.5 meters (nearly 15 feet) in diameter. In contrast, the aeroshells/heatshields of the Spirit and Opportunity Mars Exploration Rovers measured 8.5 feet and Apollo capsule heatshields measured just less than 13 feet.

Because of the unique entry trajectory profile that could create external temperatures up to 3,800 degrees Fahrenheit, the heatshield uses a tiled Phenolic Impregnated Carbon Ablator (PICA) thermal protection system instead of the Mars heritage Super Lightweight Ablator (SLA) 561V. This will be the first time PICA has flown on a Mars mission. Invented by NASA Ames Research Center, PICA was first flown as the thermal protection system on the heatshield of the Stardust Sample Return Capsule that is now in the Smithsonian Air and Space Museum.

“The Mars Science Laboratory aeroshell is the most complex capsule to fly to Mars,” said Rich Hund, MSL program manager at Lockheed Martin Space Systems Company. “The design had to address the large size and weight of the rover, the largest ever sent to Mars, and the requirement for landing at a more-precise point on Mars.”

The aeroshell has a steering capability that is produced by ejecting ballast that off-sets the center-of-mass prior to entry into the atmosphere. This off-set creates lift as it interacts with the thin Martian atmosphere and allows roll control and autonomous steering through the use of thrusters.

Prior to shipping to Kennedy Space Center, engineers will install the MSL Entry Descent and Landing Instrumentation (MEDLI) suite on the heatshield. Developed by NASA Langley Research Center, the MEDLI instrumentation will measure heatshield temperatures and atmospheric pressures as the aeroshell descends through the Martian atmosphere.

Scheduled for launch in the fall of 2011, the Curiosity rover – built by the Jet Propulsion Laboratory – will support the Mars Exploration Program’s strategy of “follow the water” and will have the science goals of determining whether the planet was ever habitable, characterizing the climate and geology of Mars, and preparing for human exploration.

(Above) After commanding five of a test rover’s six wheels to drive forward, rover driver Paolo Bellutta (left) measures how much the rover moved sideways, downslope, during the maneuver.

Using a test rover in a sandbox at JPL with special soil simulating Spirit’s predicament on Mars, engineers are assessing possible maneuvers for getting Spirit out and onto firmer ground. The tests began on Monday, July 6, with the simplest maneuver on their list of options: driving forward with all five operable wheels.

In the first set of tests, the wheels turned enough to cover tens of meters, or yards, if there had been no slippage. The test rover moved slightly forward and sideways downslope. Weeks of further testing and analysis of results are expected before engineers identify the best moves to command Spirit to make.

(Above) This mosaic of images from the Surface Stereo Imager camera on NASA’s Phoenix Mars Lander shows several trenches dug by Phoenix, plus a corner of the spacecraft’s deck and the Martian arctic plain stretching to the horizon.

Favorable chemistry and episodes with thin films of liquid water during ongoing, long-term climate cycles may sometimes make the area where NASA’s Phoenix Mars mission landed last year a favorable environment for microbes.

Interpretations of data that Phoenix returned during its five months of operation on a Martian arctic plain fill four papers in this week’s edition of the journal Science, the first major peer-reviewed reports on the mission’s findings. Phoenix ended communications in November 2008 as the approach of Martian winter depleted energy from the lander’s solar panels.

“Not only did we find water ice, as expected, but the soil chemistry and minerals we observed lead us to believe this site had a wetter and warmer climate in the recent past — the last few million years — and could again in the future,” said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson.

A paper about Phoenix water studies, for which Smith is the lead author with 36 coauthors from six nations, cites clues supporting an interpretation that the soil has had films of liquid water in the recent past. The evidence for water and potential nutrients “implies that this region could have previously met the criteria for habitability” during portions of continuing climate cycles, these authors conclude.

The mission’s biggest surprise was finding a multi-talented chemical named perchlorate in the Martian soil. This Phoenix finding caps a growing emphasis on the planet’s chemistry, said Michael Hecht of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who has 10 coauthors on a paper about Phoenix’s soluble-chemistry findings.

“The study of Mars is in transition from a follow-the-water stage to a follow-the-chemistry stage,” Hecht said. “With perchlorate, for example, we see links to atmospheric humidity, soil moisture, a possible energy source for microbes, even a possible resource for humans.”

Perchlorate, which strongly attracts water, makes up a few tenths of a percent of the composition in all three soil samples analyzed by Phoenix’s wet chemistry laboratory. It could pull humidity from the Martian air. At higher concentrations, it might combine with water as a brine that stays liquid at Martian surface temperatures. Some microbes on Earth use perchlorate as food. Human explorers might find it useful as rocket fuel or for generating oxygen.

Another surprise from Phoenix was finding ice clouds and precipitation more Earth-like than anticipated. The lander’s Canadian laser instrument for studying the atmosphere detected snow falling from clouds. In one of this week’s reports, Jim Whiteway of York University, Toronto, and 22 coauthors say that, further into winter than Phoenix operated, this precipitation would result in a seasonal buildup of water ice on and in the ground.

“Before Phoenix we did not know whether precipitation occurs on Mars,” Whiteway said. “We knew that the polar ice cap advances as far south as the Phoenix site in winter, but we did not know how the water vapor moved from the atmosphere to ice on the ground. Now we know that it does snow, and that this is part of the hydrological cycle on Mars.”

Evidence that water ice in the area sometimes thaws enough to moisten the soil comes from finding calcium carbonate in soil heated in the lander’s analytic ovens or mixed with acid in the wet chemistry laboratory. The University of Arizona’s William Boynton and 13 coauthors report that the amount of calcium carbonate “is most consistent with formation in the past by the interaction of atmospheric carbon dioxide with liquid films of water on particle surfaces.”

The new reports leave unsettled whether soil samples scooped up by Phoenix contained any carbon-based organic compounds. The perchlorate could have broken down simple organic compounds during heating of soil samples in the ovens, preventing clear detection.

The heating in ovens did not drive off any water vapor at temperatures lower than 295 degrees Celsius (563 degrees Fahrenheit), indicating the soil held no water adhering to soil particles. Climate cycles resulting from changes in the tilt and orbit of Mars on scales of hundreds of thousands of years or more could explain why effects of moist soil are present.

The Phoenix mission was led by Smith at the University of Arizona with project management at JPL and development partnership at Lockheed Martin, Denver.