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Post Info TOPIC: MESSENGER
Blobrana


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RE: MESSENGER
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A MESSENGER trajectory correction manoeuvre (TCM 10) that lasted just over two minutes and adjusted its velocity by about 1.4 meters per second, has placed the spacecraft on track for its next major mission event: the first Venus flyby on October 24, 2006.

Having completed six successful small TCMs that utilised all 17 of the spacecraft’s thrusters, this latest manoeuvre was the first to rely on the four B-side thrusters. During this manoeuvre, the thrusters on the opposite side of the spacecraft reduced a build-up of angular momentum due to an unseen force that causes the spacecraft to rotate if left uncorrected. (This manoeuvre was only the seventh actual TCM for MESSENGER; the spacecraft’s trajectory was so close to optimal after TCM 3 and TCM 6 that planned TCMs 4, 7 and 8 weren't necessary.)

The February 22nd manoeuvre started at 16:00 GMT (11 a.m. EST); mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, verified the start of the manoeuvre within 11 minutes and 48 seconds, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Goldstone, California.
At the start of the manoeuvre, the spacecraft was 212 million kilometres from Earth and 133 million kilometres from the Sun, speeding around the Sun at 109,698 kilometres per hour.

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Blobrana


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Messenger Spacecraft
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In May 2005, the messenger spacecraft managed to sent and receive a laser signal to and from it's ground station in Maryland, US, that was 24 million km away; this has established a distance record for laser transmission and detection.
The only other deep-space long-ranging demonstration took place in 1992, when two ground-based lasers were detected by cameras on the Galileo spacecraft from a distance of 6 million km.

David Smith of the Goddard SpaceFlight Centre in Greenbelt, Maryland, US, and colleagues, have reported the experiment in the latest edition of the journal Science.

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Blobrana


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RE: MESSENGER
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At 2:30 GMT today the MESSENGER spacecraft successfully fired its large bipropellant thruster for the first time since launch, completing the first of several critical deep space manoeuvres that will help the spacecraft reach Mercury orbit.

The 524-second burn changed MESSENGER’s velocity by about 316 meters per second, putting the solar-powered spacecraft on track for a 3,140-kilometer altitude flyby of Venus on October 24, 2006.

"This is a major accomplishment for the mission. That bi-prop engine is the last major component of the spacecraft that we haven’t used in space and one we’ll need at least five more times to orbit Mercury. The successful performance of this main engine proves that the spacecraft is up to the task." - Mark Holdridge, Johns Hopkins University Applied Physics Laboratory (APL), MESSENGER Mission Operations Manager.

Until today, only 16 of the MESSENGER spacecraft’s 17 thrusters had been used in five small trajectory correction manoeuvres. This latest manoeuvre, known as Deep Space Manoeuvre 1 (DSM 1), is the first to rely solely on the largest, most efficient thruster.

" Manoeuvres performed with the largest thruster use about 30% less propellant, including both fuel and oxidizer, than the other thrusters, which use fuel only. About 18 percent of MESSENGER’s propellant was used to complete DSM 1. Of all planned course-correction manoeuvres for MESSENGER, DSM 1 is second only to the March 18, 2011, Mercury orbit insertion manoeuvre in velocity change" - Jim McAdams, mission design team leader, APL.

MESSENGER controllers monitored the engine burn from the Mission Operations Centre at APL. This change in the spacecraft’s speed is about equal to the speed of a jet as it reaches the sound barrier.

"Credit for the completion of this important milestone belongs to the entire MESSENGER team. We are very fortunate to have a highly skilled group of engineers, scientists and operations experts leading our journey to Mercury. Their untiring diligence in preparing for this manoeuvre has been rewarded with a great success" - Dave Grant, MESSENGER program manager at APL.

For the next 10 months, mission controllers at APL will perform routine housekeeping tasks and fine-tune instruments to prepare MESSENGER for the Venus flyby, the first of two Venus flybys that will use the pull of the planet’s gravity to guide MESSENGER toward Mercury's orbit. This manoeuvre will occur near the beginning of an approximately two-week period when the apparent spacecraft position is too close to the Sun to allow communications with the spacecraft. So the team will spend the next several months getting the spacecraft ready to fly safely for an extended period of time without ground contact.

During a 7.9-billion kilometre journey that includes 15 trips around the Sun, MESSENGER will fly past Venus twice and Mercury three times before easing into orbit around its target planet. As with the October 2006 event, the second Venus flyby in June 2007 will be a gravity-assist manoeuvre. The Mercury flybys in January 2008, October 2008 and September 2009 will help MESSENGER match the planet's speed and location for an orbit insertion manoeuvre in March 2011 that starts the first-ever study of Mercury from orbit.

With just over 20% of the flight time completed between launch and Mercury orbit insertion, MESSENGER has travelled more than 1.3 billion kilometres around the Sun. Since its August 2004 launch, the spacecraft has completed 1.5 orbits of the Sun, including a successful flyby of Earth in August 2005.

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Blobrana


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The Narrow Angle Camera in MESSENGER’s Mercury Dual Imaging System snapped this image, showing clear morning skies over Australia, when the spacecraft was about 1.05 million kilometres from Earth. The contrast has been adjusted slightly to bring out the darker features (such as land and water) on Earth’s surface.


The Earth taken by MESSENGER on July, 30.

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Blobrana


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RE: MESSENGER flyby
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The MESSENGER spacecraft, headed toward the first study of Mercury from orbit, swung by Earth today for a gravity assist that propelled it deeper into the inner solar system.

Mission operators at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md, said MESSENGER's systems performed flawlessly. The spacecraft swooped around Earth, coming to a closest approach point of approximately 2,347 kilometres over central Mongolia at 19:13 UT.

The spacecraft used the tug of Earth's gravity to significantly change its trajectory. Its average orbit distance is nearly 18 million miles closer to the sun. The manoeuvre sent it toward Venus for another gravity-assist flyby next year.

Launched Aug. 3, 2004, from Cape Canaveral Air Force Station, Florida, US, the solar-powered spacecraft is approximately 930 million kilometres into a 7.9 billion kilometre voyage that includes 14 more loops around the sun. MESSENGER will fly past Venus twice and Mercury three times before moving into orbit.

The Venus flybys in October 2006 and June 2007 will use the planet's gravity to guide MESSENGER toward Mercury's orbit. The Mercury flybys in January 2008, October 2008 and September 2009 will help MESSENGER match the planet's speed. These events will set up the manoeuvre in March 2011 that starts a year-long science orbit around Mercury.

"This Earth flyby is the first of a number of critical mission milestones during MESSENGER's circuitous journey toward Mercury orbit insertion. Not only did it help the spacecraft sharpen its aim toward our next manoeuvre, it presented a special opportunity to calibrate several of our science instruments" - Sean C. Solomon, the mission's principal investigator from the Carnegie Institution of Washington.

MESSENGER's main camera snapped several approach shots of Earth and the moon during the past week. Today the camera is taking a series of colour images, beginning with South America and continuing for one full Earth rotation. Science team members will string the images into a video documenting MESSENGER's departure.

On Earth approach, the craft's atmospheric and surface composition spectrometer made several scans of the moon in conjunction with the camera observations. In addition, the particle and magnetic field instruments spent several hours measuring Earth's magnetosphere. The science team will download the data and images through NASA's Deep Space Network over the next several weeks, continuing assessment of the instruments' performance.

MESSENGER will conduct the first orbital study of Mercury, the least explored of the terrestrial planets that include Venus, Earth and Mars. During one Earth year (four Mercury years), MESSENGER will provide the first images of the entire planet. It will collect detailed information about the composition and structure of Mercury's crust, its geologic history, nature of its atmosphere and magnetosphere, makeup of its core and polar materials.

Adapted from source

Click Here to see graphics of MESSENGER's configuration during the manoeuvre.

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Blobrana


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Update:
The flyby of the MESSENGER spacecraft is on track for a Earth gravity assist that will send it back into the inner solar system.
It makes its closest approach to Earth about 2,347 kilometres above Mongolia at 19:13:08 UT on August 2 2005.
Observers in South America a few hours later may get a glimpse of the 14th magnitude spacecraft low in the south after sunset.


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Blobrana


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RE: Messenger
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The Messenger spacecrafts fifth trajectory has successfully carried out a correction manoeuvre that lasted just 23 seconds and adjusted its velocity by less than 15 cm per second. The fleeting July 21 manoeuvre went a long way in keeping the Messenger spacecraft on track for the upcoming gravity-assist flyby of Earth.

Carried out by two small thrusters that poke through Messenger’s sunshade, the manoeuvre pinpointed the craft for a closest approach of 2,347 kilometres over central Asia at 19:13 GMT on August. 2nd , 2005.
Mission design team members say that directing Messenger along just the right path above Earth will mean smaller course-correction manoeuvres on the way to the 2006 gravity-assist flyby at Venus – ultimately saving fuel for later in the mission.

Yesterdays manoeuvre started at 1800 GMT; mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, verified the start of the manoeuvre within 14 seconds, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Madrid, Spain.
The spacecraft was 4.3 million kilometres from Earth at the time, speeding around the Sun at 107,404 kilometres per hour.
The Earth flyby sends the spacecraft toward Venus; the first of two Venus flybys is planned for October 2006.



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Blobrana


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NASA’s Mercury-bound MESSENGER spacecraft – less than three months from an Earth flyby that will slingshot it toward the inner solar system – successfully tested its main camera by snapping distant approach shots of Earth and the Moon.




MESSENGER took a set of six pictures on May 11 with the narrow-angle camera in its Mercury Dual Imaging System, or MDIS. Earth was about 29.6 million kilometres from MESSENGER at the time, but the main processed image clearly shows bands of clouds between North and South America on Earth’s sunlit side. The image is cropped from the full MDIS image size of 1024x1024 pixels, and the contrast has been adjusted slightly to bring out the Moon in the same frame. The Moon was 400,563 kilometres from Earth.

Dr. S. Edward Hawkins III, lead engineer for MDIS at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., said finding the Moon in the pictures was an unexpected bonus. “As we stretched the image we saw this little object to the side, which turned out to be the Moon. That was exciting.”

One of seven instruments in MESSENGER’s science payload, the multispectral MDIS has wide- and narrow-angle imagers, both based on charge-coupled devices (CCDs) found in common digital cameras. MDIS has taken nearly 400 test shots since MESSENGER launched from Cape Canaveral Air Force Station last Aug. 3, but all were of star fields, dark space or a calibration target on MESSENGER's lower deck. “The team is elated. These were our first ‘real’ images, and they’re only going to get better as MESSENGER moves closer to Earth.” - Dr. Louise M. Prockter, MDIS instrument lead scientist at APL.

The photo session was just part of the preparations for the Aug. 2 Earth flyby, the first major adjustment to MESSENGER’s flight path toward Mercury. While MDIS took its pictures, the Mercury Laser Altimeter team at NASA’s Goddard Space Flight Centre in Maryland checked its instrument’s alignment by firing a high-powered laser at it from a ground-based Goddard telescope. The mission operations and science teams are also finalizing plans to calibrate several instruments – including the Magnetometer, Energetic Particle and Plasma Spectrometer, and Mercury Atmospheric and Surface Composition Spectrometer – during approach and departure observations of Earth and the Moon. Closest approach will bring MESSENGER 2,347 kilometres over northern Asia; observers with small telescopes in Japan, Eurasia and Africa will have the best chance to spot the spacecraft.

During a 7.9-billion kilometre journey that includes 15 trips around the Sun, MESSENGER will fly past Earth once, Venus twice and Mercury three times before easing into orbit around its target planet. The upcoming Earth flyby and the Venus flybys, in October 2006 and June 2007, will use the pull of the planets' gravity to guide MESSENGER toward Mercury's orbit. The Mercury flybys in January 2008, October 2008 and September 2009 help MESSENGER match the planet's speed and location for an orbit insertion manoeuvre in March 2011. The flybys also allow the spacecraft to gather data critical to planning a yearlong orbit phase.

MESSENGER, short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging, is the seventh mission in NASA's Discovery Program of lower cost, scientifically focused exploration projects. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as principal investigator.
APL manages the mission for NASA, built MESSENGER and operates the spacecraft.



Taken May 11, 2005, this processed image comes from the narrow-angle camera of the Mercury Dual Imaging System, or MDIS, on NASA’s MESSENGER spacecraft. Earth was about 29.6 million kilometres from MESSENGER at the time, but the image clearly shows bands of clouds between North and South America on Earth’s sunlit side. The photo has been cropped from the full MDIS image size of 1024 by 1024 pixels, and the contrast adjusted to bring out the Moon in the same frame.

The Moon was 400,563 kilometres from Earth at the time of the image. The photo session was just part of the preparations for MESSENGER’s gravity assist flyby of Earth on Aug. 2 – the first major adjustment to MESSENGER’s flight path toward Mercury. MESSENGER was launched on Aug. 3, 2004; after the Earth flyby, two flybys of Venus and three of Mercury, it will begin an unprecedented, yearlong science orbit around the innermost planet in March 2011.

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