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MESSENGER, Mercury Orbit Insertion Burn (2011.03.18)



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Exploring Mercury by Spacecraft: The MESSENGER Mission


The third lecture in the 2011 Exploring Space Lecture Series featured Sean C. Solomon, the Principal Investigator for the MESSENGER mission and the Director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington.
Until recently, Mercury was the least explored of the terrestrial planets, visited only by Mariner 10 in the 1970s. MESSENGER flybys in 2008 and 2009 revealed terrain seen by spacecraft for the very first time. In March 2011, as MESSENGER went into orbit, it opened a new era of comprehensive observation and study of the innermost planet, and continues to contribute to our understanding of the nature of Mercury and why it is different from its planetary neighbours. See Mercury in a new light as Sean Solomon guides us through the latest images and results.
Presented as a live webcast on Thursday, May 12, 2011 at 8pm ET at the National Air and Space Museum in Washington, DC.



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NASA Extends MESSENGER Mission

NASA has announced that it will extend the MESSENGER mission for an additional year of orbital operations at Mercury beyond the planned end of the primary mission on March 17, 2012. The MESSENGER probe became the first spacecraft to orbit the innermost planet on March 18, 2011.
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Mercurys Magnetic Mysteries - MESSENGER  results after six months in orbit

MESSENGER scientists will highlight the latest results on Mercury from MESSENGER observations obtained during the first six months (the first Mercury solar day) in orbit. These findings will be presented October 5 in 30 papers and posters as part of a special session of the joint meeting of the European Planetary Science Congress and the Division for Planetary Sciences of the American Astronomical Society in Nantes, Frances.
Scientists will also look ahead to MESSENGER observations still to come and to the dual-spacecraft BepiColombo mission of the European Space Agency and the Japan Aerospace Exploration Agency's later this decade.

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NASA Spacecraft Revealing More Details About Planet Mercury

NASA's MESSENGER spacecraft, the first to achieve orbit around Mercury, is providing scientists new information about the planet. The data show widespread flood volcanism similar to Earth, clearer views of Mercury's surface, the first measurements of its elemental composition, and details about charged particles near the planet.
MESSENGER, or the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, conducted 15 laps through the inner solar system for more than six years before achieving the historic orbit insertion March 18. The new results are reported in seven papers published in Science magazine.

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Title: Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations?
Authors: Lorenzo Iorio

The Lense-Thirring precession of the longitude of perihelion of Mercury, as predicted by general relativity by using the value of the Sun's angular momentum S = 190 x 10^39 kg m^2 s^-1 from helioseismology, is -2.0 milliarcseconds per century, computed in a celestial equatorial reference frame. It disagrees at 4-{\sigma} level with the correction 0.4 ±0.6 milliarcseconds per century to the standard Newtonian/Einsteinian precession. It was recently determined in a global fit with the INPOP10a ephemerides to a long planetary data record (1914-2010) including also 3 data points collected in 2008-2009 from the MESSENGER spacecraft. The INPOP10a models did not include the solar gravitomagnetic field at all, so that its signature might have partly been removed in the data reduction process. On the other hand, the Lense-Thirring precession may have been canceled to a certain extent by the competing precession caused by a small mismodeling in the quadrupole mass moment of the Sun, actually modeled, of the order of (0.1-0.2) x 10^-7. Future analysis of more observations from the currently ongoing MESSENGER mission will shed further light on such an issue which, if confirmed, might potentially challenge our present-day picture of the currently accepted laws of gravitation and/or of the physical properties of the Sun.

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Ed ~ Deriving any meaningful frame-dragging data from MESSENGER flybys will be very difficult, due to a host of other forces constantly affecting the spacecrafts trajectory, the time scale, and mission constraints.



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The MESSENGER probe was launched on August 3, 2004 at 06:15:56 UTC by NASA from Space Launch Complex 17B at the Cape Canaveral Air Force Station in Florida, aboard a Delta II 7925 launch vehicle.
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MESSENGER performed a successful Earth flyby a year after launch, on August 2, 2005, with the closest approach at 19:13 UTC at an altitude of 2,347 kilometres over central Mongolia.
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The US space agency's (Nasa) Messenger spacecraft is starting to open up a whole new vista on the planet Mercury.
The probe went into orbit around the inner-most world in March, and has been sending back a stream of data.
Its latest pictures from just a few hundred kilometres above the surface are expected to provide important new clues to the origin of the planet and its geological history.

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The MESSENGER spacecraft successfully completed its first orbit-correction manoeuvre yesterday to reset its periapsis altitude - the lowest point of MESSENGER's orbit about Mercury relative to the planet's surface - from 506 kilometres to approximately 200 kilometres.
MESSENGER was 198 million kilometres from Earth when the manoeuvre began at 3:40 p.m. EDT. Mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., verified the start of the manoeuvre about 10 minutes, 58 seconds later, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Goldstone, California.
This is the first of five manoeuvres planned for the primary orbital phase of the mission to keep orbital parameters within desired ranges for optimal science observations. The spacecraft's main rocket engine fired for only 15 seconds of the total manoeuvre duration of 2 minutes and 52 seconds. MESSENGER's orbital velocity was changed by a total of 28 m/s to make the corrections essential for continuing the planned measurement campaigns.

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