PASADENA, Calif. – NASA's Gravity Recovery And Interior Laboratory (GRAIL)-A spacecraft is within 24 hours of its insertion burn that will place it into lunar orbit. At the time the spacecraft crossed the milestone at 1:21 p.m. PST today (4:21 p.m. EST), the spacecraft was 30,758 miles (49,500 kilometers) from the moon.
Launched aboard the same rocket on Sept. 10, 2011, GRAIL-A's mirror twin, GRAIL-B, is also closing the gap between itself and the moon. GRAIL-B is scheduled to perform its lunar orbit insertion burn on New Year's Day (Jan. 1) at 2:05 p.m. PST (5:05 p.m. EST).
As they close in on the moon, both orbiters move toward the moon from the south, flying nearly directly over the lunar south pole. The lunar orbit insertion burn for GRAIL-A will take approximately 40 minutes to complete and change the spacecraft's velocity by about 427 mph (687 kph). GRAIL-B's insertion burn – occurring 25 hours later -- will last about 39 minutes and is expected to change its velocity by 430 mph (692 kph).
The insertion maneuvers will place each orbiter into a near-polar, elliptical orbit with an orbital period of 11.5 hours. Over the following weeks, the GRAIL team will execute a series of burns with each spacecraft to reduce their period down to just under two hours. At the start of the science phase in March 2012, the two GRAILs will be in a near-polar, near-circular orbit with an altitude of about 34 miles (55 kilometers).
During the science phase, the moon will rotate three times underneath the GRAIL orbit. The collection of gravity data over one complete rotation (27.3 days) is referred to as a Mapping Cycle. When science collection begins, the spacecraft will transmit radio signals precisely defining the distance between them as they orbit the moon in formation. Regional gravitational differences on the moon are expected to expand and contract that distance. GRAIL scientists will use these accurate measurements to define the moon's gravity field. The data will allow mission scientists to understand what goes on below the surface of our natural satellite. This information will help us learn more about how the moon, Earth and other terrestrial planets formed.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the GRAIL mission. The Massachusetts Institute of Technology, Cambridge, is home to the mission's principal investigator, Maria Zuber. The GRAIL mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. JPL is a division of the California Institute of Technology in Pasadena.
More information about GRAIL is online at: http://www.nasa.gov/grail and http://grail.nasa.gov .
The GRAIL press kit can be found online at: http://www.jpl.nasa.gov/news/press_kits/graiLaunch.pdf .
Saturday, December 31, 2011
Thursday, December 29, 2011
The Twin will Grails will arrive to Lunar Orbit this New Years Weekend.
HT Space.comGrail-A and Grail-B won't be ready to start their science campaign immediately upon arriving at the moon. Rather, they'll spend another two months circling lower and lower, eventually settling into orbits just 34 miles (55 kilometers) above the lunar surface, researchers said.
The twin probes will begin taking measurements in March. They'll chase each other around the moon for 82 days, staying 75 to 225 miles (121 to 362 km) apart.
Thursday, December 22, 2011
For those of us in the north, the days may begin to grow longer, but the coldest days are still to come. This is because ocean temperatures drive much of the weather on the continents, and they continue to cool in the relative lack of sunlight this time of year.
Read more: http://www.foxnews.com/scitech/2011/12/22/why-winter-solstice-arrives-this-week/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+foxnews%2Fscitech+%28Internal+-+SciTech+-+Mixed%29#ixzz1hGrgBda5
Wednesday, December 21, 2011
U.S. Naval Observatory
Astronomical Applications Department
Sun and Moon Data for One DayThe following information is provided for Fullerton, Orange County, California (longitude W117.9, latitude N33.9):
Wednesday 21 December 2011 Pacific Standard Time SUN Begin civil twilight 6:25 a.m. Sunrise 6:53 a.m. Sun transit 11:50 a.m. Sunset 4:47 p.m. End civil twilight 5:15 p.m. MOON Moonset 1:20 p.m. on preceding day Moonrise 3:34 a.m. Moon transit 8:53 a.m. Moonset 2:08 p.m. Moonrise 4:43 a.m. on following dayPhase of the Moon on 21 December: waning crescent with 11% of the Moon's visible disk illuminated.
New Moon on 24 December 2011 at 10:07 a.m. Pacific Standard Time.
Star Trek One Trek Mind #6: 'Twas the Night...
A Visit From St. Neelix (with apologies to Clement Clarke Moore)
'Twas the night before Christmas when all near the wormhole
Not a creature was stirring, not even a Cardassian Vole;
The gravity boots were hung by the replicator with care,
In hopes that St. Neelix soon would be there;
The children were nestled all snug in their biobeds,
While visions of moba fruit danced in their heads;
And mamma in her 'kerchief, and I in my cap,
Had just settled down for a long aphelion orbit's nap,