Friday, November 27, 2009

Prometheus Plays Tug of War with One of Saturn's Rings

Saturn's moon Prometheus
The diminutive moon Prometheus whips gossamer ice particles out of Saturn's F ring in this image taken by the Cassini spacecraft on Aug. 21, 2009. The moon and the ring have eccentric, offset orbits, so Prometheus dips in and out of the F ring as it travels around Saturn. Its gravitational force drags the dust-sized particles at the edge of the F ring along for the ride.

The ability of the potato-shaped Prometheus to pull material out of the F ring was first theorized in the late 1990s and finally imaged by Cassini in 2004. But because these so-called "streamer-channels" have constantly shifted as Prometheus and the F ring have moved, the F ring has never looked the same twice. The gravitational pull of other moons on other rings has created waves in the edges, but nothing quite as extreme as the streamer-channels of Prometheus.

Wednesday, November 25, 2009

The Crab Nebula: A Cosmic Icon

Crab Nebula
A star's spectacular death in the constellation Taurus was observed on Earth as the supernova of 1054 A.D. Now, almost a thousand years later, a super dense object -- called a neutron star -- left behind by the explosion is seen spewing out a blizzard of high-energy particles into the expanding debris field known as the Crab Nebula. X-ray data from Chandra provide significant clues to the workings of this mighty cosmic "generator," which is producing energy at the rate of 100,000 suns.

This composite image uses data from three of NASA's Great Observatories. The Chandra X-ray image is shown in blue, the Hubble Space Telescope optical images are in yellow and red, and the Spitzer Space Telescope's infrared image is in purple. The X-ray image is smaller than the others because extremely energetic electrons emitting X-rays radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. Along with many other telescopes, Chandra has repeatedly observed the Crab Nebula over the course of the mission’s lifetime. The Crab Nebula is one of the most studied objects in the sky, truly making it a cosmic icon.

Tuesday, November 24, 2009

Wise a Bit Closer to the Sky

Wise, is seen here being hoisted to the top of its United Launch Alliance Detla II rocket
NASA's Wide-field Infrared Survey Explorer, or Wise, is now perched atop its rocket at Vandenberg Air Force Base, north of Santa Barbara, Calif. The mission, which will scan the whole sky in infrared light, is scheduled to blast off on Dec. 9. It was hoisted to the top of its United Launch Alliance Delta II rocket on Friday, Nov. 20.

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The mission's principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

Monday, November 23, 2009

Cassini Sends Back Images of Enceladus as Winter Nears

unprocessed image was captured by NASA's CassiniNASA's Cassini spacecraft has sailed seamlessly through the Nov. 21 flyby of Saturn's moon Enceladus and started transmitting uncalibrated temperature data and images of the rippling terrain. These data and images will be processed and analyzed in the coming weeks. They will help scientists create the most-detailed-yet mosaic image of the southern part of the moon's Saturn-facing hemisphere and a contiguous thermal map of one of the intriguing "tiger stripe" features, with the highest resolution to date.

"These first raw images are spectacular, and paint an even more fascinating picture of Enceladus," said Bob Pappalardo, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The Cassini teams will be delving into the data to better understand the workings of this bizarre, active moon."

Scientists are particularly interested in the tiger stripes, which are fissures in the south polar region, because they spew jets of water vapor and other particles hundreds of kilometers, or miles, from the surface. This flyby was scientists' last peek at the tiger stripes before the south pole fades into the darkness of winter for several years. The thermal imaging work focused on the tiger stripe known as Baghdad Sulcus.

The Nov. 21 encounter, which is sometimes called "E8" because it is the eighth targeted flyby of Enceladus, brought Cassini to within about 1,600 kilometers (1,000 miles) of the moon's surface, at around 82 degrees south latitude. Cassini is now cruising toward Rhea, another one of Saturn's moons, for more imaging and mapping work.

Friday, November 20, 2009

Before Darkness Falls: Cassini to Scan Enceladus on Winter's Cusp

Enceladus flybyNASA's Cassini spacecraft will fly by Saturn's moon Enceladus this weekend for a last peek at the intriguing "tiger stripes" before winter darkness blankets the area for several years.

Scientists are particularly interested in the tiger stripes, which are fissures in the south polar region, because they spew jets of water vapor and other particles hundreds of kilometers, or miles, from the surface.

The flyby, which is sometimes called "E8" because it is the eighth targeted flyby of Enceladus, is scheduled for Saturday, Nov. 21 UTC, which is the evening of Friday, Nov. 20 in U.S. time zones. Cassini team members expect to fly the spacecraft to within about 1,600 kilometers (1,000 miles) of the moon's surface, at around 82 degrees south latitude. This will be a more distant flyby than the one on Nov. 2, when Cassini flew about 100 kilometers (60 miles) above the surface.

During this flyby, scientists will focus on a tiger stripe called Baghdad Sulcus and create a contiguous thermal map of the feature. The spacecraft will also be snapping high-resolution images of the southern part of the Saturn-facing hemisphere.

Wednesday, November 18, 2009

NASA and Microsoft Allow Earthlings to Become Martians

Martin NASA and Microsoft Corp. of Redmond, Wash., have collaborated to create a Web site where Internet users can have fun while advancing their knowledge of Mars.

Drawing on observations from NASA’s Mars missions, the "Be a Martian" Web site will enable the public to participate as citizen scientists to improve Martian maps, take part in research tasks, and assist Mars science teams studying data about the Red Planet.

"We're at a point in history where everyone can be an explorer," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "With so much data coming back from Mars missions that are accessible by all, exploring Mars has become a shared human endeavor. People worldwide can expand the specialized efforts of a few hundred Mars mission team members and make authentic contributions of their own."

Participants will be able to explore details of the solar system's grandest canyon, which resides on Mars. Users can call up images in the Valles Marineris canyon before moving on to chart the entire Red Planet. The collaboration of thousands of participants could assist scientists in producing far better maps, enabling smoother zoom-in views and easier interpretation of Martian surface changes.

By counting craters, the public also may help scientists determine the relative ages of small regions on Mars. In the past, counting Martian craters has posed a challenge because of the vast numbers involved. By contributing, Web site users will win game points assigned to a robotic animal avatar they select.

With a common goal of inspiring digital-age workforce development and life-long learning in science, technology, engineering and mathematics, NASA and Microsoft unveiled the Web site at the Microsoft Professional Developers Conference in Los Angeles this week. The site also beckons software developers to win prizes for creating tools that provide access to and analysis of hundreds of thousands of Mars images for online, classroom and Mars mission team use.

"Industry leaders like NASA and Microsoft have a social responsibility as well as a vested interest in advancing science and technology education," said Walid Abu-Hadba, corporate vice president of the Developer and Platform Evangelism Group at Microsoft. "We are excited to be working with NASA to provide new opportunities to engage with Mars mission data, and to help spark interest and excitement among the next generation of scientists and technologists."

To encourage more public participation, the site also provides a virtual town hall forum where users can expand their knowledge by proposing Mars questions and voting on which are the most interesting to the community. Online talks by Mars experts will address some of the submitted questions. Other features include interactive tools for viewing Martian regions and movies about people who study Mars in diverse ways.

"Mars exploration inspires people of all ages, and we are especially eager to encourage young people to explore Mars for themselves," said Charles Elachi, director of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We are delighted to be involved in providing the creative opportunity for future explorers to contribute to our understanding of Mars."

"The beauty of this type of experience is that it not only teaches people about Mars and the work NASA is doing there, but it also engages large groups of people to help solve real challenges that computers cannot solve by themselves," said Marc Mercuri, director of business innovation in the Developer and Platform Evangelism Group at Microsoft.

Saturday, November 14, 2009

LCROSS Impact Data Indicates Water on Moon

The visible camera image showing the ejecta plume at about 20 seconds after impact.
The argument that the moon is a dry, desolate place no longer holds water.

Secrets the moon has been holding, for perhaps billions of years, are now being revealed to the delight of scientists and space enthusiasts alike.

NASA today opened a new chapter in our understanding of the moon. Preliminary data from the Lunar CRater Observation and Sensing Satellite, or LCROSS, indicates that the mission successfully uncovered water during the Oct. 9, 2009 impacts into the permanently shadowed region of Cabeus cater near the moon’s south pole.

The impact created by the LCROSS Centaur upper stage rocket created a two-part plume of material from the bottom of the crater. The first part was a high angle plume of vapor and fine dust and the second a lower angle ejecta curtain of heavier material. This material has not seen sunlight in billions of years.

"We're unlocking the mysteries of our nearest neighbor and by extension the solar system. It turns out the moon harbors many secrets, and LCROSS has added a new layer to our understanding," said Michael Wargo, chief lunar scientist at NASA Headquarters in Washington.

Scientists have long speculated about the source of vast quantities of hydrogen that have been observed at the lunar poles. The LCROSS findings are shedding new light on the question of water, which could be more widespread and in greater quantity than previously suspected.

Permanently shadowed regions could hold a key to the history and evolution of the solar system, much as an ice core sample taken on Earth reveals ancient data. In addition, water, and other compounds represent potential resources that could sustain future lunar exploration.

Friday, November 13, 2009

NASA to Begin Attempts to Free Sand-Trapped Mars Rover

Computer reconstruction of spirit predicamentNASA will begin transmitting commands to its Mars exploration rover Spirit on Monday as part of an escape plan to free the venerable robot from its Martian sand trap.

Spirit has been lodged at a site scientists call "Troy" since April 23. Researchers expect the extraction process to be long and the outcome uncertain based on tests here on Earth this spring that simulated conditions at the Martian site.

"This is going to be a lengthy process, and there's a high probability attempts to free Spirit will not be successful" said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "After the first few weeks of attempts, we're not likely to know whether Spirit will be able to free itself."

Spirit has six wheels for roving the Red Planet. The first commands will tell the rover to rotate its five working wheels forward approximately six turns. Engineers anticipate severe wheel slippage, with barely perceptible forward progress in this initial attempt. Since 2006, Spirit's right-front wheel has been inoperable, possibly because of wear and tear on a motor as a result of the rover's longevity.

Spirit will return data the next day from its first drive attempt. The results will be assessed before engineers develop and send commands for a second attempt. Using results from previous commands, engineers plan to continue escape efforts until early 2010.

"Mobility on Mars is challenging, and whatever the outcome, lessons from the work to free Spirit will enhance our knowledge about how to analyze Martian terrain and drive future Mars rovers," McCuisition said. "Spirit has provided outstanding scientific discoveries and shown us astounding vistas during its long life on Mars, which is more than 22 times longer than its designed life."

In the spring, Spirit was driving backward and dragging the inoperable right front wheel. While driving in April, the rover's other wheels broke through a crust on the surface that was covering a bright-toned, slippery sand underneath. After a few drive attempts to get Spirit out in the subsequent days, it began sinking deeper in the sand trap. Driving was suspended to allow time for tests and reviews of possible escape strategies.

"The investigations of the rover embedding and our preparations to resume driving have been extensive and thorough," said John Callas, project manager for Spirit and Opportunity at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We've used two different test rovers here on Earth in conditions designed to simulate as best as possible Spirit's predicament. However, Earth-based tests cannot exactly replicate the conditions at Troy."

Data show Spirit is straddling the edge of a 26-foot-wide crater that had been filled long ago with sulfate-bearing sands produced in a hot water or steam environment. The deposits in the crater formed distinct layers with different compositions and tints, and they are capped by a crusty soil. It is that soil that Spirit's wheels broke through. The buried crater lies mainly to Spirit's left. Engineers have plotted an escape route from Troy that heads up a mild slope away from the crater.

"We'll start by steering the wheels straight and driving, though we may have to steer the wheels to the right to counter any downhill slip to the left," said Ashley Stroupe, a JPL rover driver and Spirit extraction testing coordinator. "Straight-ahead driving is intended to get the rover's center of gravity past a rock that lies underneath Spirit. Gaining horizontal distance without losing too much vertical clearance will be a key to success. The right front wheel's inability to rotate greatly increases the challenge."

Spirit has been examining its Martian surroundings with tools on its robotic arm and its camera mast. The rover's work at Troy has augmented earlier discoveries it made indicating ancient Mars had hot springs or steam vents, possible habitats for life. If escape attempts fail, the rover's stationary location may result in new science findings.

"The soft materials churned up by Spirit's wheels have the highest sulfur content measured on Mars,” said Ray Arvidson a scientist at Washington University in St. Louis and deputy principal investigator for the science payloads on Spirit and Opportunity. “We're taking advantage of its fixed location to conduct detailed measurements of these interesting materials."

Spirit and its twin rover landed on Mars in January 2004. They have explored Mars for five years, far surpassing their original 90-day mission. Opportunity currently is driving toward a large crater called Endeavor.

Wednesday, November 11, 2009

This Month in Exploration - November

Wright military flyerVisit "This Month in Exploration" every month to find out how aviation and space exploration have changed throughout the years, improving life for humans on Earth and in space. While reflecting on the events that led to NASA's formation and its rich history of accomplishments, "This Month in Exploration" will reveal where the agency is leading us -- to the moon, Mars and beyond.

100 Years Ago

November 3, 1909: Lt. George C. Sweet became the first naval officer to fly in the Wright airplane during the military trials of the Wright Flyer at College Park, Md. On the same day, Dr. William H. Greene set a passenger-carrying record at Morris Park, N.Y. A. Leo Stevens, an aviation pioneer in his own right, and two others rode as passengers for short flights in the Greene biplane.

90 Years Ago

November 12, 1919: Ross MacPherson Smith commenced his historic, 11,500-mile intercontinental flight in a British Vickers-Vimy heavy bomber aircraft in Heston, London. He completed the trip at Port Darwin, Australia on December 10, 1919 and was knighted for his efforts.

80 Years Ago

November 28-29, 1929: Commander Richard E. Byrd made the first flight over the South Pole in a Ford trimotor piloted by Bernt Balchen and two American pilots. During this first expedition to Antarctica, Byrd established a base he named Little America that was located on the Bay of Whales.

75 Years Ago

November 18, 1934: The United States Navy issued a contract to the Northrop Corporation for the XBT-1: a two-seat scout and 1,000-pound dive bomber. The aircraft was the first prototype in a sequence that led to the SBD Dauntless series of dive bombers used throughout World War II.

60 Years Ago

November 22, 1949: The Douglas D-558-II Skyrocket, a research plane, exceeded the speed of sound at Edwards Air Force Base, Calif. It was powered by both a Westinghouse J-34 turbojet engine and a Reaction Motors rocket motor.

50 Years Ago

November 4, 1959: NASA launched a second LJ-1A rocket (nicknamed Little Joe) from NASA's Wallops Flight Facility in Wallops Island, Va. to test the Mercury escape system under severe dynamic pressure. The launch vehicle functioned perfectly, but the escape rocket ignited ten seconds too late.

November 11-22, 1959: The United States contributed 10 rocket firings to an internationally coordinated program of rocket sounds of the upper atmosphere sponsored by the Committee on Space Research (COSPAR).

45 Years Ago

November 28, 1964: NASA launched the Mars explorer Mariner 4 spacecraft at 9:22 a.m. EST from the Eastern Space and Missile Center. The first successful mission to Mars, it encountered the planet on July 14, 1965.

40 Years Ago

November 14, 1969: NASA launched Apollo 12, the second lunar landing mission, at 11:22 a.m. EST from NASA's Kennedy Space Station, Fla. Astronauts Charles Conrad, Jr., Richard F. Gordon, and Alan L. Bean were aboard. The event was witnessed by Richard Nixon, the first U.S. President to attend the launch of a manned space flight.

30 Years Ago

November 21, 1979: The Eastern Space and Missile Center hosted the launch of the U.S. Air Force's Defense Satellites DSCS II-13 and 14.

25 Years Ago

November 8, 1984: NASA launched the Space Shuttle Discovery (STS-51A) from Kennedy Space Center at 7:15 a.m. EST. The satellites TELESAT-H (ANIK) and SYNCOM IV-I (also known as LEASAT-1) were deployed, while disabled satellites PALAPA-B2 and WESTAR-VI were retrieved. The mission marked the first retrieval and return of two disabled communications satellites. The mission duration was 7 days, 23 hours, 44 minutes

20 Years Ago

November 18, 1989: NASA launched the Cosmic Background Explorer (COBE ) at 6:34 a.m. PST from Vandenberg Air Force Base. This satellite was designed to measure diffuse infrared and microwave radiation from the early universe. COBE determined the temperature of the cosmic microwave background -- essentially the afterglow of the big bang.

15 Years Ago

November 3, 1994: NASA launched Space Shuttle Atlantis (STS-66) at 11:59 a.m. EDT from Kennedy Space Center. The primary payload was the Atmospheric Laboratory for Applications and Sciences - 3 (ATLAS-03), which measured and studied the hole in Earth's ozone layer. The mission duration was 10 days, 22 hours, 34 minutes.

10 Years Ago

November 26, 1999: NASA's Galileo spacecraft completed a historic flyby of Jupiter's moon, Io. Through Galileo's instruments, scientists determined that some of the volcanoes located on Io are hotter than any on Earth.

Five Years Ago

November 12, 2004: NASA's X-43A research vehicle set a new world speed record by a jet-powered aircraft when it traveled at Mach 10 - nearly 7,000 miles per hour. The X-43A's air-breathing scramjet engine has no moving parts. The aircraft is part of NASA's Hyper-X Program.

Monday, November 09, 2009

Amnesia-Like Behavior Returns on Spirit

Full-circle view from the panoramic camera
Until Oct. 24, NASA's Mars Exploration Rover had gone more than six months without an episode of amnesia-like symptoms like those that appeared on four occasions earlier this year.

In these amnesia events, Spirit fails to record data from the day's activities onto the type of computer memory -- non-volatile "flash" memory -- that can retain the data when the rover powers down for its energy-conserving periods of "sleep." The reappearance of this behavior in recent days might delay the start of planned drives by Spirit geared toward extricating the rover from a patch of soft soil where its wheels have been embedded since April.

Spirit sent data Oct. 24 through Oct. 27 indicating that the rover was not using its flash memory. The rover also has alternate memory (volatile, random-access memory) where data can be saved for communicating to Earth if the communication session comes before the next sleep period. Spirit remains in communication with Earth, maintaining good power and temperatures.

"We still don't have information about what causes these amnesia events," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "If they are intermittent and infrequent, they are a nuisance that would set us back a day or two when they occur. If the condition becomes persistent or frequent, we will need to go to an alternate strategy that avoids depending on flash memory. We would only get data collected the same day and any unsent data from an earlier day would be lost. The total volume of data returned by the rover is expected to be about the same."

This week, an independent panel of robotics experts has been reviewing the rover team's tests and plans for getting Spirit away from the site called "Troy," where the rover's wheels broke through a crusty, dark surface layer and became embedded in bright, loose material that had been hidden underneath.

Spirit has worked on Mars for more than 69 months in what was originally planned as a three-month mission.

Thursday, November 05, 2009

Frost-Covered Phoenix Lander Seen in Winter Images

Winter images of NASA's Phoenix Lander showing the lander shrouded in dry-ice frost on Mars have been captured with the High Resolution Imaging Science Experiment, or HiRISE camera, aboard NASA's Mars Reconnaissance Orbiter.

The HiRISE camera team at the University of Arizona, Tucson, captured one image of the Phoenix lander on July 30, 2009, and the other on Aug. 22, 2009. That's when the sun began peeking over the horizon of the northern polar plains during winter, the imaging team said. The first day of spring in the northern hemisphere began Oct. 26.

"We decided to try imaging the site despite the low light levels," said HiRISE team member Ingrid Spitale of the University of Arizona Lunar and Planetary Laboratory.

"The power of the HiRISE camera helped us see it even under these poor light conditions," added HiRISE team member Michael Mellon of the University of Colorado in Boulder, who was also on the Phoenix Mars Lander science team.

The HiRISE team targeted their camera at the known location of the lander to get the new images and compared them to a HiRISE image of the frost-free lander taken in June 2008. That enabled them to identify the hardware disguised by frost, despite the fact that their views were hindered by poor lighting and by atmospheric haze, which often obscures the surface at this location and season.

Carbon dioxide frost completely blankets the surface in both images. The amount of carbon dioxide frost builds as late winter transitions to early spring, so the layer of frost is thicker in the Aug. 22 image.

Wednesday, November 04, 2009

Successful Flight Through Enceladus Plume

The Cassini spacecraft has weathered the Monday, Nov. 2, flyby of Saturn's moon Enceladus in good health and has been sending images and data of the encounter back to Earth. Cassini had approached Enceladus more closely before, but this passage took the spacecraft on its deepest plunge yet through the heart of the plume shooting out from the south polar region. Scientists are eagerly sifting through the results.

In an unprocessed image (top right), sunlight brightens a crescent curve along the edge of Enceladus and highlights the moon's misty plume. The image was captured by Cassini's narrow-angle camera as the spacecraft passed about 190,000 kilometers (120,000 miles) over the moon.

A second raw image (bottom right) appears to show separate jets spewing from the moon. This image was taken from approximately 330,000 kilometers (200,000 miles) away.

At its closest point on Nov. 2, Cassini flew about 100 kilometers (60 miles) above the surface of Enceladus.

Since the discovery of the plume in 2005, scientists have been captivated by the enigmatic jets. Previous flybys detected water vapor, sodium and organic molecules, but scientists need to know more about the plume's composition and density to characterize the source, possibly a liquid ocean under the moon's icy surface. It would also help them determine whether Enceladus has the conditions necessary for life.

Tuesday, November 03, 2009

The Mars Hoax Goes Viral

For the sixth year in a row, a message about the Red Planet is infecting worldwide email boxes. It instructs readers to go outside after dark on August 27th and behold the sky. "Mars will look as large as the full moon," it says. "No one alive today will ever see this again."

Don't believe it.

Here's what will really happen if you go outside after dark on August 27th. Nothing. Mars won't be there. On that date, the red planet will be nearly 250 million km away from Earth and completely absent from the evening sky.

The Mars Hoax got its start in 2003 when Earth and Mars really did have a close encounter. On Aug. 27th of that year, Mars was only 56 million km away, a 60,000-year record for martian close approaches to Earth. Someone sent an email alerting friends to the event. The message contained some misunderstandings and omissions—but what email doesn't? A piece of advanced technology called the "forward button" did the rest.

Tolerant readers may say that the Mars Hoax is not really a hoax, because it is not an intentional trick. The composer probably believed everything he or she wrote in the message. If that's true, a better name might be the "Mars Misunderstanding" or maybe the "Confusing-Email-About-Mars-You-Should-Delete-and-Not-Forward-to-Anyone-Except-Your-In-Laws."

Another aspect of the Mars Hoax: It says "Mars will look as large as the full Moon if you magnify it 75x using a backyard telescope." The italicized text is usually omitted from verbal and written summaries of the Hoax. (For example, see the beginning of this story.) Does this fine print make the Mars Hoax true? After all, if you magnify the tiny disk of Mars 75x, it does subtend an angle about the same as the Moon.

No. Even with magnification, Mars does not look the same as a full Moon.

This has more to do with the mysterious inner workings of the human brain than cold, hard physics. Looking at Mars magnified 75x through a slender black tube (the eyepiece of a telescope) and looking at the full Moon shining unfettered in the open sky are two very different experiences.

A good reference is the Moon Illusion. Moons on the horizon look huge; Moons directly overhead look smaller. In both cases, it is the same Moon, but the human mind perceives the size of the Moon differently depending on its surroundings.

Likewise, your perception of Mars is affected by the planet's surroundings. Locate the planet at the end of a little dark tunnel, and it is going to look tiny regardless of magnification.