The image shown here is the last one acquired and transmitted back to Earth by the mission. The image is located within the floor of the 93-kilometer-diameter crater Jokai. The spacecraft struck the planet just north of Shakespeare basin. 
The image measures 0.6 miles (1 km) across. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
The image shown here is the last one acquired and transmitted back to Earth by the mission. The image is located within the floor of the 93-kilometer-diameter crater Jokai. The spacecraft struck the planet just north of Shakespeare basin. The image measures 0.6 miles (1 km) across. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Astronomy, Mercury, Missions, NASA, Observing, Science

Mercury MESSENGER Mission Concludes with a Smashing Finale!

30 Apr , 2015 by

The planet Mercury has a brand new 52-foot-wide crater. At 3:26 p.m.  EDT this afternoon, NASA’s MESSENGER spacecraft bit the Mercurial dust, crashing into the planet’s surface at over 8,700 mph just north of the Shakespeare Basin. Because the impact happened out of sight and communication with the Earth, the MESSENGER team had to wait about 30 minutes after the predicted impact to announce the mission’s end. 

NASA estimates that the MESSENGER spacecraft would crash into Mercury this afternoon at 3:26 p.m. EDT near the 30-mile-wide crater Janacek on the opposite side of the planet from Earth. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

NASA predicted that the MESSENGER spacecraft would crash into Mercury this afternoon at 3:26 p.m. EDT near the 30-mile-wide crater Janacek  and the large Shakespeare Basin on the opposite side of the planet from Earth. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Even as MESSENGER faced its demise, it continued to take pictures and gather data right up until impact. The first-ever space probe to orbit the Solar System’s innermost planet, MESSENGER has completed 4,103 orbits as of this morning. Not only has it imaged the planet in great detail, but using it seven science instruments, scientists have gathered data on the composition and structure of Mercury’s crust, its geologic history, the nature of its magnetic field and rarefied sodium-calcium atmosphere, and the makeup of its iron core and icy materials near its poles.

Color-coded view of Carnegie Rupes (ridge) with low elevations in blue and high in red. The ridge formed as the Mercury's interior cooled, resulting in the overall shrinking of the planet. Parts of the landscape lapped over other parts as the planet shrunk. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Color-coded view of Carnegie Rupes at left with low elevations in blue and high in red. The ridge formed as Mercury’s interior cooled, resulting in the overall shrinking of the planet. Parts of the landscape lapped over other parts as the planet shrunk. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Images show those ubiquitous craters but also features that set its moonlike landscape apart from the Moon including volcanic plains, tectonic landforms that indicate the planet shrank as its interior cooled and mysterious mouse-like nibbles called “hollows”, where surface material may be vaporizing in sunlight leaving behind a network of holes. To learn more about the mission’s “greatest hits”, check out its Top Ten discoveries or pay a visit to the Gallery.

The rounded, depressions, called "hollows", are a fascinating discovery of MESSENGER's orbital mission and may have been formed by vaporization of something in the material when exposed by the Raditladi impact. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The rounded depressions, called “hollows”, are a fascinating discovery of MESSENGER’s orbital mission and may have been formed by vaporization of materials in the surface when exposed by the Raditladi impact. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

MESSENGER mission controllers conducted the last of six planned maneuvers on April 24 to raise the spacecraft’s minimum altitude sufficiently to extend orbital operations and further delay the probe’s inevitable impact onto Mercury’s surface, but it’s now out of propellant. Without the ability to counteract the Sun’s gravity, which is slowly pulling the craft closer to Mercury’s surface, the team prepared for the inevitable.

False color images of Mercury taken with MESSENGER's Mercury Atmosphere and Surface Composition Spectrometer (MASCS) in everything from infrared to ultraviolet light reveal colorful differences in terrain and surface mineralogy. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

False color images of Mercury taken with MESSENGER’s Mercury Atmosphere and Surface Composition Spectrometer (MASCS) in everything from infrared to ultraviolet light reveal colorful differences in terrain and surface mineralogy. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The spacecraft actually ran out of propellant a while back, but controllers realized they could re-purpose a stock of helium, originally carried to pressurize the fuel, for a few final blasts to keep it alive and doing science right up to the last minute. During its final hours today, MESSENGER will be shooting and sending back as many new pictures as possible the same way you’d squeeze in one last shot of the Grand Canyon before departing for home. It’s also holding hundreds of older photos in its memory chip and will send as many of those as it can before the final deadline.

Farewell MESSENGER! Artist view of the spacecraft orbiting the innermost planet Mercury. Credit: NASA

Farewell MESSENGER! Artist view of the spacecraft in orbit about Mercury. Credit: NASA

“Operating a spacecraft in orbit about Mercury, where the probe is exposed to punishing heat from the Sun and the planet’s dayside surface as well as the harsh radiation environment of the inner heliosphere (Sun’s sphere of influence), would be challenge enough,” said Principal Investigator Sean Solomon, MESSENGER principal investigator. “But MESSENGER’s mission design, navigation, engineering, and spacecraft operations teams have fought off the relentless action of solar gravity, made the most of every usable gram of propellant, and devised novel ways to modify the spacecraft trajectory never before accomplished in deep space.”

Face northwest starting about 45 minutes after sunset to look for Mercury tonight. It will lie about two fists below Venus and only 1.5 from the Pleiades star cluster. Source: Stellarium

Face northwest starting about 45 minutes after sunset to find Mercury tonight. It’s located about two fists to the lower right of Venus and just 1.5° below the Pleiades star cluster. Use binoculars to see the star cluster more easily. Source: Stellarium

Ground-based telescopes won’t be able to spy MESSENGER’s impact crater because of its small size, but the BepiColombo Mercury probe, due to launch in 2017 and arrive in orbit at Mercury in 2024, should be able to get a glimpse. Speaking of spying, you can see the planet Mercury tonight (and for the next week or two), when it will be easily visible low in the northwestern sky starting about 45 minutes after sundown. The planet coincidentally makes its closest approach to the Pleiades star cluster tonight and tomorrow.

Use the occasion to wish MESSENGER a fond farewell.

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By  -      
I'm a long-time amateur astronomer and member of the American Association of Variable Star Observers (AAVSO). My observing passions include everything from auroras to Z Cam stars. I also write a daily astronomy blog called Astro Bob. Check out my forthcoming book "Night Sky with the Naked Eye", a guide to the wonders of the night using only your eyes. Available on Amazon and BN.



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Jim E
Member
Jim E
April 30, 2015 4:43 PM

“Even as MESSENGER faces its demise, it will continue to take pictures and gather data right up until impact.”
But how will it send those final pictures and data if it is hidden behind the planet? I’m guessing the actual transmission deadline is when MESSENGER drops below Mercury’s horizon for the last time. Congratulations NASA on another successful mission.

Aqua4U
Member
April 30, 2015 8:28 PM

RIP Messenger…. Thank you!

Methinks it poetic justice the Messenger Mission ended near the Shakespeare basin..

Adrian Morgan
Member
April 30, 2015 8:43 PM
So, parts of this article were written after Messenger _actually_ crashed, while other parts of this article were written when it was merely _predicted_ to crash. These two perspectives aren’t clearly demarcated, and moreover, actually overlap. The result, I’m sorry to say, is a jumbled mess. How accurate was the predicted crash location? Well, the predicted site was 54.4°N 210.1°E and it actually crashed in Jokai Crater, which Wikipedia tells me is 106km wide and centered at 72.4°N 224.7°E (converted from 135.3°W). Plugging that into Wolfram Alpha (using polar circumferences because of the high latitudes) we get a distance of 814km between the two locations, but of course it could be anything between 761km and 867km depending on… Read more »
Pvt.Pantzov
Member
May 2, 2015 1:35 AM

thanks for your service messenger and ground crew!

Bryan
Member
Bryan
May 3, 2015 8:15 AM

Another excellent article, Bob. More impressive is your timely responses to some of the comments. Well done!

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