Source – NASA /JPL Solar System Exploration:
View Saturn all night this month, and view icy moons through a telescope.
Archive for the ‘Uncategorized’ Category
NASA /JPL What’s up for April 2012
Wednesday, April 11th, 2012Total Lunar Eclipse of December 10, 2011
Saturday, December 10th, 2011Source – Nasa – Lunar Eclipse Page:
Total Lunar Eclipse of December 10
The last eclipse of 2011 is a total lunar eclipse that takes place at the Moon’s descending node in eastern Taurus, four days after apogee.
The Moon’s orbital trajectory takes it through the southern half of Earth’s umbral shadow. Although the eclipse is not central, the total phase still lasts 51 minutes. The Moon’s path through Earth’s shadows as well as a map illustrating worldwide visibility of the event are shown in Figure 6. The timings of the major eclipse phases are listed below.
Penumbral Eclipse Begins: 11:33:32 UT
Partial Eclipse Begins: 12:45:42 UT
Total Eclipse Begins: 14:06:16 UT
Greatest Eclipse: 14:31:49 UT
Total Eclipse Ends: 14:57:24 UT
Partial Eclipse Ends: 16:17:58 UT
Penumbral Eclipse Ends: 17:30:00 UT
At the instant of greatest eclipse (14:32 UT) the Moon lies at the zenith in the Pacific Ocean near Guam and the Northern Mariana Islands. The umbral eclipse magnitude peaks at 1.1061 as the Moon’s centre passes 21.4 arc-minutes south of the shadow axis. The Moon’s northern limb is then 6.4 arc-minutes south of the shadows axis and 33.3 arc-minutes from the umbra’s edge. In contrast, the Moon’s southern limb lays 36.5 arc-minutes from the shadow centre and 3.2 arc-minutes from the southern edge of the umbra. Thus, the northern half of the Moon will appear much darker than the southern half because it lies deeper in the umbra.
Since the Moon samples a large range of umbral depths during totality, its appearance will change dramatically with time. It is difficult to predict the brightness distribution in the umbra, so observers are encouraged to estimate the Danjon value at different times during totality (see Danjon Scale of Lunar Eclipse Brightness). Note that it may also be necessary to assign different Danjon values to different portions of the Moon (i.e., north vs. south).
During totality, the winter constellations are well placed for viewing so a number of bright stars can be used for magnitude comparisons. Aldebaran (mv = +0.87) is 9° to the southwest of the eclipsed Moon, while Betelgeuse (mv = +0.45) is 19° to the southeast, Pollux (mv = +1.16) is 37° east, and Capella (mv = +0.08) is 24° north.
The entire event is visible from Asia and Australia. For North Americans, the eclipse is in progress as the Moon sets with western observers favored by a larger fraction of the eclipse before moonset. Observers throughout Europe and Africa will miss the early eclipse phases because they occur before moonrise. None of the eclipse can be seen from South America or Antarctica. The NASA JavaScript Lunar Eclipse Explorer is an interactive web page that can quickly calculate the altitude of the Moon during each phase of the eclipse from any geographic location:
eclipse.gsfc.nasa.gov/JLEX/JLEX-index.html
Table 6 lists predicted umbral immersion and emersion times for 20 well-defined lunar craters. The timing of craters is useful in determining the atmospheric enlargement of Earth’s shadow (see Crater Timings During Lunar Eclipses).
The December 10 total lunar eclipse is the 23rd member of Saros 135, a series of 71 eclipses occurring in the following order: 9 penumbral, 10 partial, 23 total, 7 partial, and 22 penumbral lunar eclipses. Complete details for Saros 135 can be found at:
eclipse.gsfc.nasa.gov/LEsaros/LEsaros135.html
NASA Launches Most Capable and Robust Rover To Mars Call Curiosity
Tuesday, November 29th, 2011CAPE CANAVERAL, Fla. — NASA began a historic voyage to Mars with the Nov. 26 launch of the Mars Science Laboratory, which carries a car-sized rover named Curiosity. Liftoff from Cape Canaveral Air Force Station aboard an Atlas V rocket occurred at 10:02 a.m. EST (7:02 a.m. PST).
“We are very excited about sending the world’s most advanced scientific laboratory to Mars,” NASA Administrator Charles Bolden said. “MSL will tell us critical things we need to know about Mars, and while it advances science, we’ll be working on the capabilities for a human mission to the Red Planet and to other destinations where we’ve never been.”
The mission will pioneer precision landing technology and a sky-crane touchdown to place Curiosity near the foot of a mountain inside Gale Crater on Aug. 6, 2012. During a nearly two-year prime mission after landing, the rover will investigate whether the region has ever offered conditions favorable for microbial life, including the chemical ingredients for life.
“The launch vehicle has given us a great injection into our trajectory, and we’re on our way to Mars,” said Mars Science Laboratory Project Manager Peter Theisinger of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “The spacecraft is in communication, thermally stable and power positive.”
The Atlas V initially lofted the spacecraft into Earth orbit and then, with a second burst from the vehicle’s upper stage, pushed it out of Earth orbit into a 352-million-mile (567-million-kilometer) journey to Mars.
“Our first trajectory correction maneuver will be in about two weeks,” Theisinger said. “We’ll do instrument checkouts in the next several weeks and continue with thorough preparations for the landing on Mars and operations on the surface.”
Curiosity’s ambitious science goals are among the mission’s many differences from earlier Mars rovers. It will use a drill and scoop at the end of its robotic arm to gather soil and powdered samples of rock interiors, then sieve and parcel out these samples into analytical laboratory instruments inside the rover. Curiosity carries 10 science instruments with a total mass 15 times as large as the science-instrument payloads on the Mars rovers Spirit and Opportunity. Some of the tools are the first of their kind on Mars, such as a laser-firing instrument for checking the elemental composition of rocks from a distance, and an X-ray diffraction instrument for definitive identification of minerals in powdered samples.
To haul and wield its science payload, Curiosity is twice as long and five times as heavy as Spirit or Opportunity. Because of its one-ton mass, Curiosity is too heavy to employ airbags to cushion its landing as previous Mars rovers could. Part of the Mars Science Laboratory spacecraft is a rocket-powered descent stage that will lower the rover on tethers as the rocket engines control the speed of descent.
The mission’s landing site offers Curiosity access for driving to layers of the mountain inside Gale Crater. Observations from orbit have identified clay and sulfate minerals in the lower layers, indicating a wet history.
Precision landing maneuvers as the spacecraft flies through the Martian atmosphere before opening its parachute make Gale a safe target for the first time. This innovation shrinks the target area to less than one-fourth the size of earlier Mars landing targets. Without it, rough terrain at the edges of Curiosity’s target would make the site unacceptably hazardous.
The innovations for landing a heavier spacecraft with greater precision are steps in technology development for human Mars missions. In addition, Curiosity carries an instrument for monitoring the natural radiation environment on Mars, important information for designing human Mars missions that protect astronauts’ health.
The mission is managed by JPL, a division of the California Institute of Technology in Pasadena, for NASA’s Science Mission Directorate in Washington. The rover was designed, developed and assembled at JPL. NASA’s Launch Services Program at the Kennedy Space Center in Florida managed the launch. NASA’s Space Network provided space communication services for the launch vehicle. NASA’s Deep Space Network will provide spacecraft acquisition and mission communication.
For more information about the mission, visit: http://www.nasa.gov/msl and http://marsprogram.jpl.nasa.gov/msl/ .
Asteroid 2005 YU55 to Approach Earth on November 8, 2011
Saturday, November 5th, 2011Source – NASA Near Earth Object Program (NEO):
Don Yeomans, Lance Benner and Jon Giorgini
March 10, 2011
Trajectory of Asteroid 2005 YU55 - November 8-9, 2011
Click on image for animation
Near-Earth asteroid 2005 YU55 will pass within 0.85 lunar distances from the Earth on November 8, 2011. The upcoming close approach by this relatively large 400 meter-sized, C-type asteroid presents an excellent opportunity for synergistic ground-based observations including optical, near infrared and radar data. The attached animated illustration shows the Earth and moon flyby geometry for November 8th and 9th when the object will reach a visual brightness of 11th magnitude and should be easily visible to observers in the northern and southern hemispheres. The closest approach to Earth and the Moon will be respectively 0.00217 AU and 0.00160 AU on 2011 November 8 at 23:28 and November 9 at 07:13 UT.
Discovered December 28, 2005 by Robert McMillan of the Spacewatch Program near Tucson Arizona, the object has been previously observed by Mike Nolan, Ellen Howell and colleagues with the Arecibo radar on April 19-21, 2010 and shown to be a very dark, nearly spherical object 400 meters in diameter. Because of its approximate 20-hour rotation period, ideal radar observations should include tracks that are 8 hours or longer on multiple dates at Goldstone (November 3-11) and when the object enters Arecibo’s observing window on November 8th.
Using the Goldstone radar operating in a relatively new “chirp” mode, the November 2011 radar opportunity could result in a shape model reconstruction with a resolution of as fine as 4 meters. Several days of high resolution imaging (about 7.5 meters) are also planned at Arecibo. As well as aiding the interpretation of the radar observations, collaborative visual and near infrared observations could define the object’s rotation characteristics and provide constraints upon the nature of the object’s surface roughness and mineral composition.
Since the asteroid will approach the Earth from the sunward direction, it will be a daylight object until the time of closest approach. The best time for new ground-based optical and infrared observations will be late in the day on November 8, after 21:00 hours UT from the eastern Atlantic and western Africa zone. A few hours after its close Earth approach, it will become generally accessible for optical and near-IR observations but will provide a challenging target because of its rapid motion across the sky.
Trajectory of Asteroid 2005 YU55 - November 9, 2011
Although classified as a potentially hazardous object, 2005 YU55 poses no threat of an Earth collision over at least the next 100 years. However, this will be the closest approach to date by an object this large that we know about in advance and an event of this type will not happen again until 2028 when asteroid (153814) 2001 WN5 will pass to within 0.6 lunar distances.
Falling German satellite ROSAT X-ray astronomy observatory
Friday, October 21st, 2011Source -Spaceflight Now.
Less than a month after NASA’s falling UARS satellite grabbed the headlines, the German space agency says one of its abandoned satellites will dive back to Earth later this month, but no one knows where it will land.
The ROSAT X-ray astronomy observatory is smaller and less massive than NASA’s Upper Atmospheric Research Satellite, or UARS, which fell back to Earth on Sept. 24. But officials predict it will spread three times more debris and pose a greater threat to people than UARS.
That’s because ROSAT is made of heat-resistant components, especially its primary mirror, which officials say will probably be the largest single fragment that will reach Earth.
The satellite will streak into the atmosphere at 17,000 mph, and temperatures up to 3,000 degrees Fahrenheit will burn up much of the spacecraft.
“All these forces exerted on the satellite cause it to disintegrate, which in turn means that it eventually lands in the form of a long debris trail,” said Heiner Klinkrad, head of the European Space Agency’s space debris office. “The lightweight objects fall to Earth first, similar to leaves from a tree. The really heavy objects land later, because they ultimately have to drill their way through the atmosphere.”
But engineers expect the bulk of ROSAT to survive re-entry, littering its impact point with up to 30 pieces of debris.
The 5,348-pound satellite launched from Florida on a Delta 2 rocket in 1990. ROSAT does not have an engine or propulsion system because it used reaction wheels to point its telescope toward scientific targets in the cosmos.
Up to 3,750 pounds of the satellite could reach Earth’s surface. NASA said they expected 1,200 pounds of UARS to survive re-entry.
There is a 1-in-2,000 chance someone will be struck by fragments of ROSAT on its way down, according to Germany. That equates to odds of about 1-in-14 trillion that any individual person will be hit.
The threat from UARS wasn’t as high. An analysis from NASA showed there was a 1-in-3,200 chance of a collision between a human and a piece of UARS.
The remnants of UARS fell in the remote Pacific Ocean, and ROSAT will likely also end up in the sea, but its impossible to tell where it will crash until hours before.
ROSAT launched in June 1990 on a Delta 2 rocket.
ROSAT, which stands for Roentgen Satellite, was turned off in 1999, and its altitude has gradually dropped since then from an operational orbit more than 350 miles high. The German Aerospace Center, also known as DLR by its German acronym, says the spacecraft should re-enter the atmosphere between Oct. 20 and Oct. 25.
But the margin of error in the re-entry forecast is three days, and officials likely won’t know where the satellite will come down until after it falls. Even one day before re-entry, the time of ROSAT’s demise will only be known with a precision of plus-or-minus five hours, putting entire oceans and continents in the satellite’s flight path.
“All areas under the orbit of ROSAT, which extends to 53 degrees northern and southern latitude could be affected by its re-entry,” said a posting on DLR’s website. “The bulk of the debris will impact near the ground track of the satellite.”
“It will not be possible to make any kind of reliable forecast about where the satellite will actually come down until about one or two hours before the fact,” Klinkrad said. “It will, however, be possible to predict, about one day in advance, which geographical regions will definitely not be affected.”
ROSAT’s orbit was at an average altitude of 149 miles Wednesday.
“This slow descent is due to the friction encountered by the satellite as it enters the outer fringes of Earth atmosphere, which increases the more ROSAT penetrates into our atmosphere,” Klinkrad said.
Klinkrad said the major factor affecting a satellite’s fall from orbit is solar activity. Energy unleashed from the sun causes Earth’s atmosphere to heat up and expand, generating more drag for satellites in low orbits.
Fluctuations in solar activity can quicken or slow a satellite’s re-entry. Experts initially expected ROSAT’s plunge to occur last year, but solar activity turned out to be less than predicted, delaying the re-entry until this month.
NASA \ JPL What’s Up for October 2011?
Wednesday, October 5th, 2011Source – NASA /JPL Solar System Exploration:
Look for moons and meteors this month!
NASA: What’s Up For September 2011?
Sunday, September 18th, 2011Source – NASA /JPL Solar System Exploration:
Enjoy a tour of lunar landing sites as NASA’s GRAIL mission launches to the moon this month.
Cassini Spacecraft Captures Images and Sounds of Big Saturn Storm
Friday, July 8th, 2011Source – NASA/JPL Cassini :
PASADENA, Calif. – Scientists analyzing data from NASA’s Cassini spacecraft now have the first-ever, up-close details of a Saturn storm that is eight times the surface area of Earth.
On Dec. 5, 2010, Cassini first detected the storm that has been raging ever since. It appears at approximately 35 degrees north latitude on Saturn. Pictures from Cassini’s imaging cameras show the storm wrapping around the entire planet covering approximately 1.5 billion square miles (4 billion square kilometers).
The storm is about 500 times larger than the biggest storm previously seen by Cassini during several months from 2009 to 2010. Scientists studied the sounds of the new storm’s lightning strikes and analyzed images taken between December 2010 and February 2011. Data from Cassini’s radio and plasma wave science instrument showed the lightning flash rate as much as 10 times more frequent than during other storms monitored since Cassini’s arrival to Saturn in 2004. The data appear in a paper published this week in the journal Nature.
“Cassini shows us that Saturn is bipolar,” said Andrew Ingersoll, an author of the study and a Cassini imaging team member at the California Institute of Technology in Pasadena, Calif. “Saturn is not like Earth and Jupiter, where storms are fairly frequent. Weather on Saturn appears to hum along placidly for years and then erupt violently. I’m excited we saw weather so spectacular on our watch.”
At its most intense, the storm generated more than 10 lightning flashes per second. Even with millisecond resolution, the spacecraft’s radio and plasma wave instrument had difficulty separating individual signals during the most intense period. Scientists created a sound file from data obtained on March 15 at a slightly lower intensity period.
Cassini has detected 10 lightning storms on Saturn since the spacecraft entered the planet’s orbit and its southern hemisphere was experiencing summer, with full solar illumination not shadowed by the rings. Those storms rolled through an area in the southern hemisphere dubbed “Storm Alley.” But the sun’s illumination on the hemispheres flipped around August 2009, when the northern hemisphere began experiencing spring.
“This storm is thrilling because it shows how shifting seasons and solar illumination can dramatically stir up the weather on Saturn,” said Georg Fischer, the paper’s lead author and a radio and plasma wave science team member at the Austrian Academy of Sciences in Graz. “We have been observing storms on Saturn for almost seven years, so tracking a storm so different from the others has put us at the edge of our seats.”
The storm’s results are the first activities of a new “Saturn Storm Watch” campaign. During this effort, Cassini looks at likely storm locations on Saturn in between its scheduled observations. On the same day that the radio and plasma wave instrument detected the first lightning, Cassini’s cameras happened to be pointed at the right location as part of the campaign and captured an image of a small, bright cloud. Because analysis on that image was not completed immediately, Fischer sent out a notice to the worldwide amateur astronomy community to collect more images. A flood of amateur images helped scientists track the storm as it grew rapidly, wrapping around the planet by late January 2011.
The new details about this storm complement atmospheric disturbances described recently by scientists using Cassini’s composite infrared spectrometer and the European Southern Observatory’s Very Large Telescope. The storm is the biggest observed by spacecraft orbiting or flying by Saturn. NASA’s Hubble Space Telescope captured images in 1990 of an equally large storm.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena manages the mission for the agency’s Science Mission Directorate in Washington. The radio and plasma wave science team is based at the University of Iowa, Iowa City, where the instrument was built. The imaging team is based at the Space Science Institute in Boulder, Colo. JPL is a division of the California Institute of Technology, Pasadena.
For images and an audio file of the storm, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .
Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov
Dwayne C. Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov
2011-203
Voyager Space Craft’s Still Doing Science after all These Years.
Thursday, June 9th, 2011The Voyager space probes are now some 9 billion miles from the Sun, and have discovered some interesting facts about the Sun’s Magnetic Field way out there.
NASA/JPL What’s Up for June 2011?
Sunday, June 5th, 2011Source – NASA:
What’s up for June? Solar system collisions!
