Posted on by Fraser Cain

Mars Reconnaissance Orbiter Camera Ready

Image credit: Ball Aerospace
The camera that will take thousands of the sharpest, most detailed pictures of Mars ever produced from an orbiting spacecraft was delivered today for installation on NASA’s Mars Reconnaissance Orbiter.

The Mars Reconnaissance Orbiter (MRO) will be launched on Aug. 10, 2005, carrying a payload of six science instruments and a communications relay package to boost the ongoing exploration of the red planet.

The largest science instrument on the spacecraft will be the University of Arizona’s High Resolution Imaging Science Experiment (HiRISE), a 65 kilogram (145 pound) camera with a half-meter (20-inch) diameter primary mirror.

HiRISE has been delivered for installation on the MRO spacecraft at Lockheed Martin Space Systems in Denver, Colo. Ball Aerospace & Technologies Corp. of Boulder, Colo., designed, built and tested the $35 million HiRISE camera. NASA’s Jet Propulsion Laboratory in Pasadena, Calif., manages the MRO mission for NASA’s Science Mission Directorate, Washington, D.C.

HiRISE will produce ultra-sharp photographs over 6 kilometer (3.5 mile) swaths of the martian landscape with a best imaging at 25 centimeters (10 inches) per pixel, said Alfred S. McEwen of the UA’s Lunar and Planetary Laboratory, principal investigator for HiRISE.

“By combining a fine imaging scale (25 centimeters to 32 centimeters a pixel, or 10 inches to 12.5 inches a pixel) and high signal-to-noise ratio, it is possible to resolve features as small as one meter (about 40 inches) wide, a scale currently well-studied only by landers,” McEwen said. “HiRISE will get such views over any selected region of Mars, providing a bridge between orbital remote sensing and landed missions.” Mission scientists will combine stereo image pairs to produce detailed maps of the topography and combine images taken with filters to produce false-color images.

HiRISE will study deposits and landforms created by geologic and climatic processes, and it will help scientists assess future Mars mission landing sites.

(The next Mars lander will be NASA’s first Scout mission, called “Phoenix,” scheduled for launch in 2007. Peter Smith of UA’s Lunar and Planetary Lab heads the Phoenix mission, the first mission to Mars being led by an academic institution.)

“Ball Aerospace has done a fantastic job building an instrument that meets our challenging performance requirements,” McEwen said. “The HiRISE camera can collect the equivalent of about a thousand megapixel images in just three seconds.”

“With the delivery of the HiRISE hardware, team activities now shift to the UA and Lockheed Martin,” McEwen said. “We’ll do a series of flight-like tests before the spacecraft gets shipped to Kennedy Space Center next spring.” In these operational readiness tests, data from the camera on the spacecraft at Lockheed Martin will be sent to NASA’s Jet Propulsion Laboratory in Pasadena, Calif., then to the HiRISE Operations Center (HiROC) on the UA campus in Tucson.

“Rather than data coming down from the Deep Space Network, which will happen once the spacecraft is actually orbiting Mars, we’ll command HiRISE as it sits in a clean room at Lockheed Martin,” Eric Eliason said. Eliason manages activities at HiROC, which is located in the Lunar and Planetary Lab’s Sonett Building.

A dozen people currently staff HiROC. That number will double when the primary mission begins in 2006. Their tasks include writing command software, planning observations, uplinking commands, downlinking data, processing raw data into useful images and monitoring the instrument, Eliason said.

HiRISE co-investigators are:

* Candice Hansen, Jet Propulsion Laboratory, deputy principal investigator
* Alan Delamere, Delamere Support Systems
* Eric Eliason, UA
* Virginia Gulick, NASA Ames/SETI Institute
* Ken Herkenhoff, USGS Flagstaff
* Nathan Bridges, Jet Propulsion Laboratory
* Nick Thomas, University of Bern (Switzerland)
* Randolph Kirk, USGS Flagstaff
* John Grant, Smithsonian Institution
* Laszlo Keszthelyi, USGS Flagstaff
* Mike Mellon, University of Colorado
* Steve Squyres, Cornell University
* Cathy Weitz, Planetary Science Institute (Tucson)

The Mars Reconnaissance Orbiter scheduled for launch in August 2005 will be captured in Mars orbit by a “Mars orbit insertion” maneuver in March 2006.

Initially, the spacecraft will fly around Mars in a highly elliptical orbit. The orbit will become more circular over the next several months by a technique called “aerobraking.” On each of its close swings by Mars in elliptical orbit, the spacecraft is low enough that it skims the surface of Mars’ atmosphere, creating drag on the spacecraft. The orbiter’s path around the planet becomes more circular on each successive planet flyby.

HiRISE will begin taking photographs when the spacecraft is in a circular orbit, in November 2006. The primary science mission is for two years, or slightly more than a martian year. The orbiter can also serve as a telecommunications relay link for landers launched to Mars in 2007 and 2009. Nominally, the orbiter mission ends Dec. 31, 2010.

Original Source: University of Arizona News Release

Posted on by Fraser Cain

Huygens Ready to Go Solo

One year after Mars Express? arrival at Mars, the mighty rules of celestial mechanics have again set Christmas as the date for a major ESA event in deep space.

At 1.25 billion km from Earth, after a 7-year journey through the Solar system, ESA?s Huygens probe is about to separate from the Cassini orbiter to enter a ballistic trajectory toward Titan, the largest and most mysterious moon of Saturn, in order to dive into its atmosphere on 14 January. This will be the first man-made object to explore in-situ this unique environment, whose chemistry is assumed to be very similar to that of the early Earth just before life began, 3.8 billion years ago.

The Cassini-Huygens pair, a joint mission conducted by NASA, ESA and the Italian space agency (ASI), was launched into space on 15 October 1997. With the help of several gravity assist manoeuvres during flybys of Venus, Earth and Jupiter, it took almost 7 years for the spacecraft to reach Saturn.

The Cassini orbiter, carrying Huygens on its flank, entered an orbit around Saturn on 1 July 2004, and began to investigate the ringed planet and its moons for a mission that will last at least four years.

The first distant flyby of Titan took place on 2-3 July 2004. It provided data on Titan’s atmosphere which were confirmed by the data obtained during the first close flyby on 26 October 2004 at an altitude of 1174 km. These data were used to validate the entry conditions of the Huygens probe. A second close flyby of Titan by Cassini-Huygens at an altitude of 1200 km is scheduled on 13 December and will provide additional data to further validate the entry conditions of the Huygens probe.

On 17 December the orbiter will be placed on a controlled collision course with Titan in order to release Huygens on the proper trajectory, and on 21 December (some dates and times are subject to minor adjustment for operational reasons, except the entry time on 14 January which is know to within an accuracy of under 2 minutes) all systems will be set up for separation and the Huygens timers will be set to wake the probe a few hours before its arrival at Titan.

The Huygens probe is due to separate on the morning of 25 December at about 05:08 CET. Since the Cassini orbiter will have to achieve precise pointing for the release, there will be no real-time telemetry available until it turns back its main antenna toward Earth and beams the recorded data of the release. It will take over an hour (67 min) for the signals to reach us on Earth. The final data confirming the separation will be available later on Christmas Day.

After release, Huygens will move away from Cassini at a speed of about 35 cm per second and, to keep on track, will spin on its axis, making about 7 revolutions a minute. Huygens will not communicate with Cassini for the whole period until after deployment of the main parachute following entry into Titan?s atmosphere. On 28 December Cassini will then manoeuvre off collision course to resume its mission and prepare itself to receive Huygens data, which it will record for later playback to Earth.

Huygens will remain dormant until a few hours before its arrival at Titan on 14 January. The entry into the atmosphere is set for 11:15 CET. Huygens is planned to complete its descent in about two hours and 15 minutes, beaming back its science data to the Cassini orbiter for replay to Earth later in the afternoon. If Huygens, which is designed as an atmospheric probe rather than a lander, survives touchdown on the surface, it could deliver up to 2 hours of bonus data before the link with Cassini is lost.

Direct radio signals from Huygens will reach Earth after 67 minutes of interplanetary travel at the speed of light. An experiment has been set up by radio scientists that will use an array of radio telescopes around the Pacific to attempt to detect a faint tone from Huygens. If successful, early detection is not expected before around 11:30 CET.

The European Space Agency owns and manages the Huygens probe and is in charge of operations of the probe from its control centre in Darmstadt, Germany. NASA’s Jet Propulsion Laboratory in Pasadena, California, designed, developed and assembled the Cassini orbiter. NASA’s Deep Space Network, also managed by JPL, will be providing communications support via the Cassini orbiter and relaying it to ESA?s control centre in Darmstadt for processing. The Italian Space Agency provided the high-gain antenna on the Cassini orbiter, much of the radio system and elements of several of Cassini’s science instruments. The Huygens payload has been provided by teams including from CNES, DLR, ASI and PPARC, and outside Europe, from NASA.

Original Source: ESA News Release

Posted on by Fraser Cain

What’s Up This Week – Dec 6 – Dec 12, 2004

Image credit: David Malin
Monday, December 6 – If you’re up before dawn this morning, be sure to take a moment to step outside and have a look at the Moon and Jupiter. This morning the Moon will appear above and to the right of the “Mighty Jove”, but tomorrow morning they are going to be a whole lot closer! And speaking of closer, somewhere out there in the asteroid belt, it’s going to be a busy Monday because Asteroid 2002 YP2, Asteroid 12382 Niagara Falls and Asteroid 12397 Peterbrown all make their nearest approach to the Earth today.

For Northern Hemisphere observers, today Comet C/2004 Q1 (Tucker) is at perihelion, or the nearest point in its orbit of the Sun today. With an estimated magnitude of 10, Comet Tucker should be visible to both large binoculars and small telescopes sliding through Andromeda just a bit southwest of M31. As with all comets, activity increases as they near the Sun, so be on the lookout for coma or above average brightenings.

Tonight’s unusual treat is for the Southern Hemisphere viewer when the Phoenicid meteor shower reaches its peak. With an estimated fall rate of about 5 per hour, this particular shower might not seem very exciting, but it has an unusual place in history. In 1956 over 100 meteors per hour were recorded, marking the point of this shower’s discovery. The stream is believed to be the offspring of the long lost periodic comet Blanpain observed in 1819. Although the exact time of peak activity is currently unpredictable, past observations show this meteor shower begins right after sunset and radiates from constellation of Phoenix. It is unusual because it leaves very few visible trails but is well-known for its bright flashes and exploding fireballs! Lucky birds…

Tuesday, December 7 – Wake up North America! This morning is a grand occulation of Jupiter by the Moon. Encompassing Canada and the biggest majority of the United States (for you who are still warm? sorry… you’ll only get a grazing event.) the Moon will silently slide over Jupiter at the unholy hour of just before 4:00 a.m. Since timing is especially critical in these type of events, you must visit the IOTA predictions for precise times in your area. (relax Florida keys and south Texas, there’s times in there for your graze as well.) This provides a wonderful opportunity for photographs as well as just a spectacular event to witness. It is especially fitting since the Galileo spacecraft went into orbit around Jupiter on this day in 1995. So hug your loved one, hug your scope, hug your dog, or just watch Venus and Mars still hugging the horizon and enjoy!

While waiting on Jupiter to re-appear, those of you with large aperture telescopes might like to take the opportunity to view Comet Tsuchinshan at perihelion this morning. Although this comet has been holding a recent magnitude of 13, it may reach an estimated magnitude of 11 by this time. It has moved quietly across the southern border of Leo for the last few weeks and should be quite near Beta Leonis and the Coma Berenices border at this time.

On a side note, Apollo 17 was launched on this date in 1972, Gerard Kuiper belted his way into fame by being born on this day in 1905 and this is also the earliest sunset of the year. Astronomers? Let’s celebrate!

Wednesday, December 8 – If you are out this morning before dawn, take a moment to find bright Venus down on the horizon and work your way up the sky as Mars, the crescent Moon, Spica, and Jupiter form nearly a straight line across the winter skies.

Asteroid 4701 Milani, Asteroid 2004 RZ164, Asteroid 3353 Jarvis and Asteroid 2062 Aten all make their closest approach to the Earth today and Comet C/2004 S1(Van Ness) is at perihelion. At a rough magnitude of 16, this newly discovered comet will be in the range of professional observing. Ephemerides are provided by following the link (and I’ll see you at the observatory).

For binoculars and small telescopes, tonight would be a great opportunity to hunt down a southern Messier object in Capricornus. At magnitude 8, the M30 can be found just a bit over 6 degrees south of Gamma Capricorni. To smaller aperture telescopes and large binoculars, this 40,000 light year distant globular cluster will appear small and faint, but larger telescopes will see a dense, bright core and splendid resolution. As an added bonus, 41 Capricorni (in the same field of view) is a double star!

Thursday, December 9 – Looking for an unusual photo opportunity? Then check out Mars this morning as it appears almost between the very slender crescent Moon and Venus. Coupled with “earth shine” this trio will be very low on the horizon!

While we’re enjoying early evening dark skies, the window opens for binoculars and small telescopes to locate one of the largest and most spectacular of the southern globular clusters – the M2! By heading north/northeast of Beta Aquarii (remember this star – we’ll use it again), the 6th magnitude M2 (NGC7089) will show to small aperture scopes as well as binoculars and turn into stunning resolution in the large telescope. Cataloged by Messier 1760, this 150 light year wide “ball of stars” might seem less impressive than the M13, but at 50,000 light years in distance it’s significantly further away!

Southern Hemisphere viewers, you’re in luck again! Tonight will be the maximum of the Puppid-Velid meteor shower. With an average fall rate of about 10 per hour, this particular meteor showing could also be visible to those far south enough to see the constellation of Puppis. Very little is known about this meteor shower except for the streams and radiants are very tightly bound together. Since studies of the Puppid-Velids are just beginning, why not take the opportunity to watch? Viewing will be all night long and although most of the meteors are faint, it is known to produce an occasional fireball.

Friday, December 10 – Do you think you can catch Luna one last time? Then try again this morning as the Moon will make its final dawn appearance very close to the horizon. Just above it will be Venus, and higher to the left will be tiny Mars. Missing Mercury is now at perihelion – its closest approach to the Sun – but it is also at inferior conjunction, making it invisible to us because it is hiding between the Earth our “nearest star”.

Tonight will be the peak of the Monocerotid meteor shower. Here again we have an example of an obscure and unstudied shower because no one is sure of exactly where the precise radiant is located. By keeping watch loosely on the constellations of Gemini and Monoceros, you may see a few of these faint and fast meteors at a rate of 3-12 per hour. Who knows? Perhaps one of these strange meteors may have been responsible for the observed fall in 1984 that hit a Claxton mailbox!

While out viewing tonight, take advantage of the moonless early evening to try hunting down a very large and elusive galaxy that can be spotted with binoculars and even unaided from a very dark observing site. The M33, or “Triangulum Galaxy” is very misty, vague and also a totally wonderful galaxy for study. Just west of Alpha Triangulum, this galaxy is about the size of the full Moon, but it is so diffuse it’s sometimes hard to locate. Cataloged by Charles Messier in August 1764, the M33 is often known as the “Pinwheel”, because of its distinguishable arm structure. As a part of our local galaxy group, the M33 (NGC598) is quite prized by amateurs for its ability to resolve. It has a distinct concentration toward the nucleus area plus a northern and southern “arm” that are within a small telescope’s capabilities. Telescopes ranging between 12.5″ to 16″ and larger will find a wealth of NGC and IC objects hiding within this fantastic galaxy, allowing us to study star clusters and nebula almost 750,000 light years away. It’s out there tonight!

Saturday, December 11 – For those of you who like to get up early to capture space oddities, this morning Mars will occult TYC 6174-00681-1 (10.2 magnitude star).

On this date in 1863, Annie Jump Cannon was born. She was a United States astronomer who created the modern system for classifying stars by their spectra. Why not celebrate this achievement by coming along with me and viewing some very specific stars that have unusual visual spectral qualities! Let’s grab a star chart, brush up on our Greek letters and start first with Mu Cephei. Nicknamed the “Garnet Star”, this is perhaps one of the most red stars visible to the unaided eye. At around 1200 light years away, this spectral type M2 star will show a delightful blue/purple “flash”. If you still don’t perceive color, try comparing Mu to its bright neighbor Alpha, a spectral type A7, or “white” star. Perhaps you’d like something a bit more off the beaten path? Then head for S Cephei about halfway between Kappa and Gamma toward the pole. Its intense shade of red makes this magnitude 10 star an incredibly worthwhile hunt.

To see an example of a B spectrum star, look no further than the Plieades. All the components are blue white. Want to taste an “orange”? Then look again at Aldeberan, or Alpha Tauri, and say hello to a K spectrum star. Now that I have your curiosity aroused, would you like to see what our own Sun would look like? Then chose Alpha Aurigae, better known as Capella, and discover a spectral class G star that’s only 160 times brighter than the one that holds our solar system together! If you’re enjoying the game, then have a look at one of the most unusual spectral stars of all – Theta Aurigae. Theta is actually a B class, or a blue/white but instead of having strong lines in the helium, it has an abnormal concentration of silicon, making this incredibly unusual double star seem to glitter like a “black diamond”.

Still no luck in seeing color? Don’t worry. It does take a bit of practice! The cones in our eyes are the color receptors and when we go out in the dark, the color-blind rods take over. By intensifying the starlight with either a telescope or binoculars, we can usually excite the cones in our dark-adapted eyes to pick up on color. While you’re out tonight waiting on the meteor shower, try watching Orion. it contains several stars of different spectra! For the Southern Hemisphere, have a look at the Southern Cross as well. Awesome!

Tonight will also be the peak of the Sigma Hydrid meteor shower. With its radiant near the bright star, Procyon, this will make an nice “all hemispheres” type of show. But don’t hold your breath… The Sigma Hydrids are famous for being both notoriously fast and faint. With a predicted fall rate of about 3-12 per hour at maximum, this is not a spectacular show, but thanks to the new Moon tonight, you might stand a chance at catching a meteor that is normally only observed by the most serious of sky watchers.

Sunday, December 12 – Today the Moon at perigee and will be about 358,002 km or 222,452 miles away from Earth. If this make you feel like singing the “blues”, then why don’t we take advantage of dark skies and hunt down two very unique planetary nebulae tonight!

Our first will be the NGC7662, more commonly known as “The Blue Snowball”. Starting in the constellation of Andromeda, you will find this unique nebula by locating Iota and Omicron Andromedae and identifying the fifth magnitude star 13, about one-third the distance between them. The NGC7662 is approximately one-half a degree southwest. Shining at a decent magnitude 8, the “Blue Snowball” is achievable in large binoculars and very small telescopes, but due to its size, it will appear almost stellar. By upping the magnification you will find the NGC7662 to be a wonderfully blue “disc” that has a central star that can be spotted with larger telescopes. At around 5600 light years away, this unusual character is very similar to our next study!

Moving on to the constellation of Aquarius, recall our earlier study of the M2 and re-locate Beta. Now hop southwest to bright star, Nu. Only one degree west of Nu you will find the NGC7009, or the “Saturn Nebula”. Also shining at a magnitude 8, the NGC7009 can be spotted in large binoculars and small scopes, but requires the use of high power to understand “why” it is so named. Larger instruments will easily reveal that the NGC7009 has two extensions, or “lobes” that make it appear visually like the planet Saturn! As a high surface brightness object, its central star is also a extremely hot blue dwarf that emits a continuous spectrum. Large telescopes can reveal a substantial amount of detail in this particular planetary nebula, but most simply enjoy it for its unique shape and “electric” coloration. Best of luck!

(Be aware that the most prolific of all meteor showers – the Geminids – peaks on December 13. Observers may wish to start their vigil before dawn tomorrow! Full information will be provided in next week’s issue.)

Until next week fellow SkyWatchers, keep looking up and thinking – the Universe is out there waiting to be explored! Wishing you clear skies and light speed… ~Tammy Plotner

Posted on by Fraser Cain

Astronauts Running Low on Food

The International Space Station?s Expedition 10 crewmembers completed the first 50 days of their six-month mission this week, highlighted by a short flight in their Soyuz spacecraft.

To put the Station in the preferred configuration for two spacewalks out of the Russian Pirs Docking Compartment next year, Commander Leroy Chiao and Flight Engineer Salizhan Sharipov moved their ISS Soyuz 9 spacecraft Monday from Pirs to the Earth-facing docking port on the Zarya module during a 21-minute flight. The work to prepare the Station for possible autonomous operations, and then to reconfigure it for normal operations, stretched from Sunday afternoon until early Monday afternoon.

After getting off duty time Tuesday and Wednesday to rest, Chiao and Sharipov spent the rest of the week on routine maintenance tasks, such as the regeneration of filter cartridges in the Elektron oxygen generation system. They also completed audits of on board computer hardware and food as mission managers finalize the appropriate manifest for the next Russian cargo craft. The ISS Progress 16 spacecraft will ferry food, fuel, clothing and other supplies to the Station. The audit of food supplies aboard the Station confirmed that sufficient food remains for the crew until arrival of the next supply craft. Managers have adjusted the amount of food to be carried on the Progress, however, to ensure onboard stores are fully replenished.

Included in the cargo are three laptop computers that will return the Station Support Computer network to full functionality. This week, one of the computers that crewmembers use to access messages while working at the Zvezda module?s command post, failed. Another computer is being temporarily moved from Sharipov?s sleep station to the command post until the new laptops are delivered.

The new Progress cargo ship is targeted for launch from the Baikonur Cosmodrome in Kazakhstan at 4:19 p.m. CST on Dec. 23 (2219 GMT), and is due to arrive at the Station just after 6 p.m. CST on Christmas night (0005 GMT on Dec. 26).

Chiao and Sharipov will spend time over the next three weeks loading unneeded materials from throughout the Station into the Progress currently mated to the Zvezda module. It will be undocked and deorbited on Dec. 22.

On Tuesday, Sharipov located a missing component of an American spacesuit?s cooling pump. The shim, a washer-shaped piece of metal that is custom fit for each spacesuit, was missing last month at a time when Chiao was repairing the spacesuit?s pump assembly. The shim was planned to be installed in a portion of the spacesuit in a pure oxygen environment to ensure it is in pristine condition and free of contamination. Spacewalk specialists at the Johnson Space Center decided further spacesuit repair attempts will utilize a new shim to be delivered on the upcoming Progress to avoid any potential contamination from the shim that was temporarily lost.

Information on the crew’s activities aboard the Space Station, future launch dates, as well as Station sighting opportunities from anywhere on the Earth, is available on the Internet at:

http://spaceflight.nasa.gov/

Details on Station science operations can be found on an Internet site administered by the Payload Operations Center at NASA’s Marshall Space Flight Center in Huntsville, Ala., at:

http://scipoc.msfc.nasa.gov/

Original Source: NASA Status Report

Posted on by Fraser Cain

Sweeping View of Saturn’s Rings

Any doubts about the grandeur of Saturn’s rings will be dissolved by sweeping portraits like this one from Cassini. There is a magnificent level of detail visible in this view, which captures almost the entire ring system — from the thin, outer F ring to faint narrow features in the D ring, interior to the C ring. Along the ringplane, differences in brightness reveal the varying concentrations of the particles that comprise the rings.

Cassini is viewing the rings from below. The portion of the rings near the top of the image is closer to the spacecraft, and the portion near the bottom is farther away.

The image was taken with the Cassini spacecraft wide angle camera on Oct. 29, 2004, at a distance of about 836,000 (519,000 miles) from Saturn through a filter sensitive to wavelengths of infrared light centered at 742 nanometers. The image scale is 46 kilometers (29 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org .

Posted on by Fraser Cain

Prometheus Disrupting Saturn’s Rings

As it completed its first orbit of Saturn, Cassini zoomed in on the rings to catch this wondrous view of the shepherd moon Prometheus (102 kilometers, or 63 miles across) working its influence on the multi-stranded and kinked F ring.

The F ring resolves into five separate strands in this closeup view. Potato-shaped Prometheus is seen here, connected to the ringlets by a faint strand of material. Imaging scientists are not sure exactly how Prometheus is interacting with the F ring here, but they have speculated that the moon might be gravitationally pulling material away from the ring. The ringlets are disturbed in several other places. In some, discontinuities or “kinks” in the ringlets are seen; in others, gaps in the diffuse inner strands are seen. All these features appear to be due to the influence of Prometheus.

The image was taken in visible light with the narrow angle camera on Oct. 29, 2004, at a distance of about 782,000 kilometers (486,000 miles) from Prometheus and at a Sun-Prometheus-spacecraft, or phase, angle of 147 degrees. The image scale is 4.7 kilometers (2.9 miles) per pixel. The image has been magnified by a factor of two, and contrast was enhanced, to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Mars Was Once Suitable For Life

Image credit: NASA
Scientists have long been tantalized by the question of whether life once existed on Mars. Although present conditions on the planet would seem to be inhospitable to life, the data sent back over the past 10 months by NASA’s two exploration rovers, Spirit and Opportunity, showed a world that might once have been warmer and wetter — perhaps friendly enough to support microbial organisms.

Now a Cornell University-led Mars rover science team reports on the historic journey by the rover Opportunity, which is exploring a vast plain, Meridiani Planum, and concludes with this observation: “Liquid water was once present intermittently at the martian surface at Meridiani, and at times it saturated the subsurface. Because liquid water is a key prerequisite for life, we infer that conditions at Meridiani may have been habitable for some period of time in martian history.”

The article is one of 11 published this week (Dec. 3, 2004) in a special issue of the journal Science, authored by scientists connected with the Mars rover mission, several from Cornell and from the Jet Propulsion Laboratory in Pasadena, Calif., the mission’s manager. The issue covers Opportunity through its first 90 days of exploring its landing site of Eagle crater in Meridiani Planum. This was before the rover drove to and entered the large crater dubbed Endurance, from which it is now about to emerge.

Steve Squyres, Cornell professor of astronomy and leader of the rovers’ Athena science team, is the lead author of the main paper, “The Opportunity Rover’s Athena Science Investigation at Meridiani Planum, Mars.” In another paper, on which he is also the lead author, Squyres again refers to the geological record at Meridiani Planum as suggesting that conditions were suitable for “biological activity” for a period of time in the history of mars. In the article, “In Situ Evidence for an Ancient Aqueous Environment at Meridiani Planum, Mars,” he writes: “We cannot determine whether life was present or even possible in the waters at Meridiani, but it is clear that by the time the sedimentary rocks in Eagle crater were deposited, Mars and Earth had already gone down different environmental paths. Sample return of Meridiani rocks might well provide more certainty regarding whether life developed on Mars.”

The Mars rover mission is not designed to look for microbial life but to look for evidence of whether conditions were once right for life. As Squyres recently stated, “What we were seeking was rocks that were actually formed in liquid water so that we could read the record in those rocks, not just to say liquid water was on Mars but to learn something about what the environmental conditions were like, would they have been suitable for life and, importantly, do the minerals that were formed have the capability to preserve for long periods of time evidence of former life? That’s probably the single most important thing we have found: evidence for minerals at Meridiani that are the kinds of things that are very good at preserving evidence of ancient life for very long periods of time.”

Opportunity bounced down on Jan. 25, 22 days after its twin, the rover Spirit, landed on the opposite side of Mars in Gusev crater. Last August Science published a special issue on Spirit.

“This is the first peer-reviewed presentation of the data from Opportunity,” notes Jim Bell, Cornell associate professor of astronomy and the lead scientist for the rovers’ Pancam color imaging system.

Bell also is prominent in the special issue of Science , including his lead authorship of a paper, “Pancam Multispectral Imaging Results from the Opportunity Rover at Meridiani Planum.”

When Opportunity landed on the red planet last January, the robot geologist sent back images of its landing site that were unlike any of the other places where earlier lander probes and rovers had gone. Instead of rusty deserts of dusty soil and boulders strewn to the horizon, Opportunity had landed in a relatively small crater in a vast sea of sand nearly devoid of rocks. Fortunately, an intriguing outcrop of bedrock presented itself nearby, which scientists hoped would be a sample of the original crust underneath the layers of dust.

The scientists were not disappointed. Scattered among the outcrop rocks were large numbers of small, round mineral deposits that the Athena science team named “blueberries.” On Earth, such formations appear when large amounts of water course through rock layers, leaching out the iron-bearing minerals into small spherical rocks and granules. The rovers also detected large amounts of sulfate salt deposits. Enough evidence was collected by Opportunity in the two months it spent examining Eagle crater that the science team felt confident enough to announce in early March that liquid water had flowed over the crater’s rocks long ago, possibly for a long time. Following on this, the latest Science articles largely focus on Opportunity’s most important scientific and geological accomplishment: the discovery of evidence that liquid water once flowed through the region.

Like the coverage given to Spirit in the August issue of Science , the latest edition contains several foldouts with big color panoramas and images from Opportunity’s region of exploration.

Original Source: Cornell News Release

Posted on by Fraser Cain

Greenland Glacier Speeds Up

When people talk about something moving at a glacial pace, they are referring to speeds that make a tortoise look like a hare. While it is all relative, glaciers actually flow at speeds that require time lapses to recognize. Still, researchers who study Earth’s ice and the flow of glaciers have been surprised to find the world’s fastest glacier in Greenland doubled its speed between 1997 and 2003.

The finding is important for many reasons. For starters, as more ice moves from glaciers on land into the ocean, it raises sea levels. Jakobshavn Isbrae is Greenland’s largest outlet glacier, draining 6.5 percent of Greenland’s ice sheet area. The ice stream’s speed-up and near-doubling of ice flow from land into the ocean has increased the rate of sea level rise by about .06 millimeters (about .002 inches) per year, or roughly 4 percent of the 20th century rate of sea level increase.

Also, the rapid movement of ice from land into the sea provides key evidence of newly discovered relationships between ice sheets, sea level rise and climate warming.

The researchers found the glacier’s sudden speed-up also coincides with very rapid thinning, indicating loss of ice of up to 15 meters (49 feet) in thickness per year after 1997. Along with increased rates of ice flow and thinning, the thick ice that extends from the mouth of the glacier into the ocean, called the ice tongue, began retreating in 2000, breaking up almost completely by May 2003.

The NASA-funded study relies on data from satellites and airborne lasers to derive ice movements. The paper appears in this week’s issue of the journal Nature.

“In many climate models glaciers are treated as responding slowly to climate change,” said Ian Joughin, the study’s lead author. “In this study we are seeing a doubling of output beyond what most models would predict. The ice sheets can respond rather dramatically and quickly to climate changes.” Joughin conducted much of this research while working at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Joughin is currently a glaciologist at the Applied Physics Laboratory at the University of Washington, Seattle.

The researchers used satellite and other data to observe large changes in both speeds and thickness between 1985 and 2003. The data showed that the glacier slowed down from a velocity of 6700 meters (4.16 miles) per year in 1985 to 5700 meters (3.54 miles) per year in 1992. This latter speed remained somewhat constant until 1997. By 2000, the glacier had sped up to 9400 meters (5.84 miles) per year, topping out with the last measurement in spring 2003 at 12,600 meters (7.83 miles) per year.

“This finding suggests the potential for more substantial thinning in other glaciers in Greenland,” added Waleed Abdalati, a coauthor and a senior scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md. “Other glaciers have thinned by over a meter a year, which we believe is too much to be attributed to melting alone. We think there is a dynamic effect in which the glaciers are accelerating due to warming.”

Airborne laser altimetry measurements of Jakobshavn’s surface elevation, made previously by researchers at NASA’s Wallops Flight Facility, showed a thickening, or building up of the glacier from 1991 to 1997, coinciding closely with the glacier’s slow-down. Similarly, the glacier began thinning by as much as 15 meters (49 feet) a year just as its velocity began to increase between 1997 and 2003.

The acceleration comes at a time when the floating ice near the glacier’s calving front has shown some unusual behavior. Despite its relative stability from the 1950’s through the 1990s, the glacier’s ice tongue began to break apart in 2000, leading to almost complete disintegration in 2003. The tongue’s thinning and breaking up likely reduced any restraining effects it had on the ice behind it, as several speed increases coincided with losses of sections of the ice-tongue as it broke up. Recent NASA-funded research in the Antarctic Peninsula showed similar increases in glacier flow following the Larson B ice shelf break-up.

Mark Fahnestock, a researcher at the University of New Hampshire, Durham, N.H., was also a co-author of this study.

Original Source: NASA News Release

Posted on by Fraser Cain

Wallpaper: Saturn’s Rings in Black and White

This close-up of the lit side of Saturn’s outer B ring and the Cassini Division looks something like a phonograph record. There are subtle, wavelike patterns, hundreds of narrow features resembling a record’s ‘grooves’ and a noticeable abrupt change in overall brightness beyond the dark gap near the right. To the left of the gap is the outer B ring with its sharp edge maintained by a strong gravitational resonance with the moon Mimas. To the right of the Huygens Gap are the plateau-like bands of the Cassini Division. The narrow ringlet within the gap is called the Huygens ringlet.

The image was taken in visible light with the Cassini spacecraft narrow angle camera on Oct. 29, 2004, at a distance of about 819,000 (509,000 miles) from Saturn. The image scale is 4.5 kilometers (2.8 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org .

Posted on by Mark Mortimer

Book Review: Centauri Dreams

First a bit of a background. We’ve a long way to go. Alpha Centauri is 4.3 light years away (about 13 zeros after the one when considering kilometres). Voyager 1, the fastest man made object, is speeding at 3.6 AU’s per year (about 8 zeros after the one in kilometres per year). Were a person to be on it, some 100,000 years would pass before entering Alpha Centauri’s solar system. This won’t happen as Voyager 1 travels another path, but this is the problem in a nutshell, it’s too far for today’s chemically driven rockets. With most people expecting a return on investment well within ten years then there would be little support in waiting thousands of generations for payback. Given this impracticality Gilster presents options and methods that might reduce the travel time to within one generation.

The first chapter sets the background of who’s doing what, where they are keeping themselves busy and, sometimes, when their activities first appear upon the scene. Scores of researchers’ names arise, especially physicists, mathematicians and astronomers, but a sprinkling of other esoteric specialists such as Internet designers, clearly demonstrates the broad response to this challenge. NASA’s programs and facilities predominate. CERN appears as does the Brookhaven National Laboratory. Early visionaries from the 1800’s and even earlier make a brief appearance. Applicable science fiction stories from the early 1900’s get noted, while the predominance of technically valid work dates from about 1960 on. This shows that on the whole, considerable thought and work has gone into advancing concepts for high speed interstellar travel.

Five chapters follow and represent the real meat of this book. These look at different methods of getting a useful payload to our neighbouring stars and they focus on well known and lesser known means of propulsion. Antimatter, sails, ramjets and fusion runways get their dues. Field-drives, providing force from the interaction of matter and fields get an honourable mention. Each chapter clearly and simply describes the methods of the chosen propulsion and the state (or technical level) of the research. Interviews with today’s investigators provide a superb insider’s view of activities. If you’re looking to identify locations for grad studies, there is a bonus as key investigating sites get identified alongside. Exciting sections detail the latest in experiments and technical investigations. The Planetary Society’s solar sail lifts off soon, antimatter is getting expansive new containers, lasers push model crafts up against Earth’s gravitational pull and a mini-magentospheric plasma propulsion prototype undergoes testing. Each of these might answer the riddle about how we propel ourselves at near light speed but as pointed out, the breakthrough technology may yet be around the corner.

One chapter seems a little bit like a lost child. This deals with communication and guidance. Of course these issues will need to be addressed, but it seems a bit early to be worrying about setting up extra-planetary webs or designing their communication protocol for that real long distance feeling. The guidance/navigation portion seems equally out of place. As the propulsion method so drastically constrains the mission, this discussion is preemptive. Still, as the title states, this book plans for interstellar exploration, hence communication and guidance are relevant and their consideration is warranted.

And yes, the title says it all. Alpha Centauri is a dreamers destination but dreams are only the beginning. Imagination gets us out of the constraints of everyday thinking and planning will see that effort gets well applied. As depicted within the book, many people share this dream. Some are incredibly lucky and can make it their life’s work. Others contribute directly in their part time or indirectly whether through related research, writing fiction or, as Gilster is undertaking, performing outreach activities. The link from imagination, to serious consideration and eventual trials constantly arises as either a sign of humanity’s adaptability or perhaps a sign of genetic coding. Nevertheless, time and again, imaginations are shown to conceive of the knowledge that thrusts plans out of the realm of fiction and into the laboratory where researchers make it reality.

Stars twinkle all about us at night. Perhaps maliciously inviting or teasing like a temptress, either way they remain today too far to fathom visiting today. Science fiction had imaginaries who gave detailed if somewhat fanciful means of propulsion between the stars. Paul Gilster in Centauri Dreams: Imagining and Planning Interstellar Exploration shows that real science is advancing technologies that could make this trip practical. The plans of the scientists and other technical may soon bear fruit and future generations of humans would have a much better and more exciting life amongst the stars.

Read more reviews online or order your own copy from Amazon.com.

Review by Mark Mortimer