[FPSPACE] FW: NASA/JPL: Twin Spacecraft on Final Approach for Moon Orbit

LARRY KLAES ljk4 at msn.com
Wed Dec 28 15:21:28 EST 2011

 > Date: Wed, 28 Dec 2011 14:26:25 -0500
> Subject: NASA/JPL: Twin Spacecraft on Final Approach for Moon Orbit
> From: rick.fienberg at aas.org
> To: Rick.Fienberg at aas.org
> Fienberg, AAS Press Officer: rick.fienberg at aas.org, +1 202-328-2010
> x116.
> December 28, 2011
> Contacts:
> DC Agle
> Jet Propulsion Laboratory, Pasadena, Calif.
> +1 818-393-9011
> agle at jpl.nasa.gov
> Dwayne Brown
> Headquarters, Washington, D.C.
> +1 202-358-1726
> dwayne.c.brown at nasa.gov
> Caroline McCall
> Massachusetts Institute of Technology, Cambridge
> +1 617-253-1682
> cmcall5 at mit.edu
> Text:
> http://www.nasa.gov/home/hqnews/2011/dec/HQ_11-426_GRAIL_Highlights.html
> Images & Videos:
> http://www.nasa.gov/mission_pages/grail/news/telecon20111228.html
> NASA’s twin spacecraft to study the Moon from crust to core are
> nearing their New Year’s Eve and New Year’s Day main-engine burns to
> place the duo in lunar orbit.
> Named Gravity Recovery And Interior Laboratory (GRAIL), the spacecraft
> are scheduled to be placed in orbit beginning at 1:21 p.m. PST (4:21
> p.m. EST) for GRAIL-A on Dec. 31, and 2:05 p.m. PST (5:05 p.m. EST)
> for GRAIL-B the next day.
> “Our team may not get to partake in a traditional New Year’s
> celebration, but I expect seeing our two spacecraft safely in lunar
> orbit should give us all the excitement and feeling of euphoria anyone
> in this line of work would ever need,” said David Lehman, project
> manager for GRAIL from NASA’s Jet Propulsion Laboratory in Pasadena,
> Calif.
> The distance from Earth to the Moon is approximately 250,000 miles
> (402,000 kilometers). NASA’s Apollo crews took about three days to
> travel to the Moon. Launched from Cape Canaveral Air Force Station
> Sept. 10, 2011, the GRAIL spacecraft are taking about 30 times that
> long and covering more than 2.5 million miles (4 million kilometers)
> to get there.
> This low-energy, long-duration trajectory has given mission planners
> and controllers more time to assess the spacecraft’s health. The path
> also allowed a vital component of the spacecraft’s single science
> instrument, the Ultra Stable Oscillator, to be continuously powered
> for several months. That allowed it to reach a stable operating
> temperature long before science measurements from lunar orbit are to
> begin.
> “This mission will rewrite the textbooks on the evolution of the
> Moon,” said Maria Zuber, GRAIL principal investigator from the
> Massachusetts Institute of Technology in Cambridge, Mass. “Our two
> spacecraft are operating so well during their journey that we have
> performed a full test of our science instrument and confirmed the
> performance required to meet our science objectives”.
> As of Dec. 28, GRAIL-A is 65,860 miles (106,000 kilometers) from the
> Moon and closing at a speed of 745 miles per hour (1,200 kilometers
> per hour). GRAIL-B is 79,540 miles (128,000 kilometers) from the Moon
> and closing at a speed of 763 mph (1,228 kilometers per hour).
> During their final approaches to the Moon, both orbiters move toward
> it from the south, flying nearly directly over the lunar south pole.
> The lunar orbit insertion burn for GRAIL-A will take approximately 40
> minutes and change the spacecraft’s velocity by about 427 mph (688
> kilometers per hour). GRAIL-B’s insertion burn 25 hours later will
> last about 39 minutes and is expected to change the probe’s velocity
> by 430 mph (691 kilometers per hour).
> The insertion maneuvers will place each orbiter into a near-polar,
> elliptical orbit with a period of 11.5 hours. Over the following
> weeks, the GRAIL team will execute a series of burns with each
> spacecraft to reduce their orbital period from 11.5 hours 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).
> When science collection begins, the spacecraft will transmit radio
> signals precisely defining the distance between them as they orbit the
> Moon. As they fly over areas of greater and lesser gravity, caused
> both by visible features such as mountains and craters and by masses
> hidden beneath the lunar surface. they will move slightly toward and
> away from each other. An instrument aboard each spacecraft will
> measure the changes in their relative velocity very precisely, and
> scientists will translate this information into a high-resolution map
> of the Moon’s gravitational field. The data will allow mission
> scientists to understand what goes on below the surface. This
> information will increase our knowledge of how Earth and its rocky
> neighbors in the inner solar system developed into the diverse worlds
> we see today.
>                            # # #
> Note to Media:
> Media interested in attending a GRAIL-related function at JPL during
> the lunar orbit insertion burn of GRAIL-A on Dec. 31 from noon to
> about 2:30 p.m. PST, must call or email DC Agle at +1 818-393-9011 or
> agle at jpl.nasa.gov. Those media in attendance will witness a
> presentation regarding the GRAIL mission and see a closed-circuit
> television feed of events as they unfold at the nearby GRAIL mission
> support area. They will also be able to interview GRAIL principal
> investigator Maria Zuber after successful orbit insertion. While there
> will be no access to JPL for media on Jan. 1, mission personnel will
> be available for phone interviews.
> 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:
>  * http://www.nasa.gov/grail
>  * http://grail.nasa.gov
> GRAIL press kit:
>  * http://www.jpl.nasa.gov/news/press_kits/graiLaunch.pdf
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