MESSENGER Archives

September 22, 2014December 23, 2015 by Jason Major

MESSENGER Completes Second Burn to Maintain Mercury Orbit

Illustration of MESSENGER in orbit around Mercury (NASA/JPL/APL)

A little over a week before NASA’s MAVEN spacecraft fired its rockets to successfully enter orbit around Mars, MESSENGER performed a little burn of its own – the second of four orbit correction maneuvers (OCMs) that will allow it to remain in orbit around Mercury until next March. Although it is closing in on the end of its operational life it’s nice to know we still have a few more months of images and discoveries from MESSENGER to look forward to!

MESSENGER's orientation after the start of orbit correction maneuver 10 (OCM-10). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — MESSENGER’s orientation after the start of orbit correction maneuver 10 (OCM-10). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The first OCM burn was performed on June 17, raising MESSENGER’s orbit from 115 kilometers (71.4 miles) to 156.4 kilometers (97.2 miles) above the surface of Mercury. That was the ninth OCM of the MESSENGER mission, and at 11:54 a.m. EDT on Sept. 12, 2014, the tenth was performed.

According to the mission news article:

At the time of this most recent maneuver, MESSENGER was in an orbit with a closest approach of 24.3 kilometers (15.1 miles) above the surface of Mercury. With a velocity change of 8.57 meters per second (19.17 miles per hour), the spacecraft’s four largest monopropellant thrusters (with a small contribution from four of the 12 smallest monopropellant thrusters) nudged the spacecraft to an orbit with a closest approach altitude of 94 kilometers (58.4 miles). This maneuver also increased the spacecraft’s speed relative to Mercury at the maximum distance from Mercury, adding about 3.2 minutes to the spacecraft’s eight-hour, two-minute orbit period.

OCM-10 lasted for 2 1/4 minutes and added 3.2 minutes to the spacecraft’s 8-hour, 2-minute-long orbit. (Source)

The next two burns will occur on October 24 and January 21.

After its two final successful burns MESSENGER will be out of propellant, making any further OCMs impossible. At the planned end of its mission MESSENGER will impact Mercury’s surface in March of 2015.

WATCH: A Tribute to MESSENGER

Built and operated by The Johns Hopkins University Applied Physics Laboratory (JHUAPL), MESSENGER launched from Cape Canaveral Air Force Station on August 3, 2004. It entered orbit around Mercury on March 18, 2011, the first spacecraft ever to do so. Since then it has performed countless observations of our Solar System’s innermost planet and has successfully mapped 100% of its surface. Check out the infographic below showing some of the amazing numbers racked up by MESSENGER since its launch ten years ago, and read more about the MESSENGER mission here.

"MESSENGER by the Numbers" - and infographic by NASA — “MESSENGER by the Numbers” – an infographic by NASA

June 18, 2014December 23, 2015 by Jason Major

Mercury’s Hot Flow Revealed by MESSENGER

A hot flow anomaly, or HFA, has been identified around Mercury (Credit: NASA/Duberstein)

Our Sun is constantly sending a hot stream of charged atomic particles out into space in all directions. Pouring out from holes in the Sun’s corona, this solar wind flows through the Solar System at speeds of over 400 km/s (that’s 893,000 mph). When it encounters magnetic fields, like those generated by planets, the flow of particles is deflected into a bow shock — but not necessarily in a uniform fashion. Turbulence can occur just like in air flows on Earth, and “space weather” results.

One of the more curious effects is a regional reversal of the flow of solar wind particles. Called a “hot flow anomaly,” or HFA, these energetic phenomena occur almost daily in Earth’s magnetic field, as well as on Jupiter and Saturn, and even on Mars and Venus where the magnetic fields are weak (but there are still planets blocking the stream of charged particles.)

Not to be left out in the cold, Mercury is now known to display HFAs, which have been detected for the first time by the MESSENGER spacecraft.

A NASA news release describes how the HFAs were confirmed:

The first measurement was of magnetic fields that can be used to detect giant electric current sheets that lead to HFAs. The second was of the heating of the charged particles. The scientists then analyzed this information to quantify what kind of turbulence exists in the region, which provided the final smoking gun of an HFA.

“Planets have a bow shock the same way a supersonic jet does,” explains Vadim Uritsky at NASA’s Goddard Space Flight Center. “These hot flow anomalies are made of very hot solar wind deflected off the bow shock.”

The solar wind is not 100% uniform; it has discontinuities within its own complex magnetic fields. When these shifting fields pile up against a planet’s bow shock they can create turbulence patterns that trap hot plasma, which in turn produces its own magnetic fields. The shockwaves, heat, and energy produced are powerful enough to actually reverse the flow of the solar wind within the HFA bulge.

And the word “hot” is putting it lightly — plasma temperatures in an HFA can reach 10 million degrees.

Mercury may be only a little larger than our Moon but it does possess an internally-generated dipolar magnetic field, unlike the Moon, Venus, and Mars which have only localized or shallow fields. The confirmed presence of HFAs on Mercury indicates that they may be a feature in all planetary bow shocks, regardless of how their magnetic fields — if any — are produced.

The team’s results were published in the February 2014 issue of the Journal of Geophysical Research: Space Physics.

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In related news, on June 17 MESSENGER successfully completed the first orbit adjustment maneuver to prepare it for its new — and final — low-altitude campaign, during which it will obtain its highest-resolution images ever of the planet’s surface and perform detailed investigations of its composition and magnetic field. Read more on the MESSENGER site here.

Source: NASA

May 15, 2014December 23, 2015 by Jason Major

Mercury’s Ready For Its Close-Up, Mr. MESSENGER

One of the highest-resolution images of Mercury's surface ever acquired.

Are you ready for a good close look at Mercury? At an incredible 5 meters per pixel, this is one of the highest-resolution images of Mercury’s surface ever captured. It was acquired on March 15 with the MESSENGER spacecraft’s MDIS (Mercury Dual Imaging System) instrument and shows an 8.3-km (5.2-mile) -wide section of Mercury’s north polar region, speckled with small craters and softly rolling hills.

Because MESSENGER was moving so quickly relative to the targeted area it was imaging, a short exposure time was necessary to avoid blurring. As a result the image appears a bit grainy. See the original map projection here.

Wondering what the next-best image was of Mercury? Find out below:

The previous record for most extreme close-up of Mercury was held by this image:

7 meter/pixel targeted observation of Mercury by the MESSENGER spacecraft

It was acquired as a targeted observation by MESSENGER’s Narrow-Angle Camera on April 30, 2012, and has a resolution of 7 meters/pixel. It shows an impact melt-covered area about 11 km (7 miles) across near Gaugin crater.

(Although Mercury’s surface may at first appear strikingly similar to the Moon’s, it’s been known since the Mariner 10 mission that the two worlds are very different at fundamental geologic and compositional levels. Read more on that here.)

Images like these are extremely special; during the first two years of MESSENGER’s mission in orbit around Mercury, over 150,000 images were acquired but only five images had resolutions better than 10 meters per pixel.

Artist's impression of MESSENGER orbiting Mercury — Artist’s impression of MESSENGER orbiting Mercury

On April 20, 2014, MESSENGER completed its 3,000th orbit of Mercury (3,075 to date) and is steadily moving into an even lower-altitude orbit. MESSENGER now comes within less than 200 km (124 miles) of the planet’s surface when it passes over its north pole every eight hours… that’s less than half the altitude of the Space Station!

Orbiting at such a low altitude and so often will allow MESSENGER to examine Mercury’s surface in unprecedented detail. Now that 100% of the planet has been successfully mapped by MESSENGER it can spend its second — and last — extended mission investigating specific scientific targets.

Watch: A Tribute to MESSENGER

“The final year of MESSENGER’s orbital operations will be an entirely new mission,” said Sean Solomon, Principal Investigator for MESSENGER. “With each orbit, our images, our surface compositional measurements, and our observations of the planet’s magnetic and gravity fields will be higher in resolution than ever before. We will be able to characterize Mercury’s near-surface particle environment for the first time. Mercury has stubbornly held on to many of its secrets, but many will at last be revealed.”

Read more in a recent news release from the MESSENGER team here.

Want to explore a high-res map of Mercury and see where MESSENGER is right now? Click here.

Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

April 9, 2014December 23, 2015 by Elizabeth Howell

Mercury Had Quite The Explosive Past, Spacecraft Analysis Shows

Mercury — a planet once thought to have no volcanism at all — likely had a very active past, a new analysis of images from NASA’s MESSENGER spacecraft shows. After looking at 51 vents across Mercury, the team concluded that they show different amounts of erosion — hinting that the explosions happened at different times in the planet’s history.

“If [the explosions] happened over a brief period and then stopped, you’d expect all the vents to be degraded by approximately the same amount,” stated Goudge, a graduate geology student at Brown University who led the research.

“We don’t see that; we see different degradation states. So the eruptions appear to have been taking place over an appreciable period of Mercury’s history.”

Information came from orbital data collected from MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) since 2011, which provided more consistent data than the previous flybys, the researchers added. To better figure out the age of these vents, they examined those that are located in impact craters; any vents there before the impact occurred would have been wiped out.

Two pyroclastic vents in Mercury's Kipler crater in optical (top) and false-color views from NASA's MESSENGER spacecraft. Pyroclastic material is in brown-red in the bottom image. The vents were likely too fragile to survive the impact of the crater, scientists said, showing that they likely arose after the impact occurred. Credit: Brown University/NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — Two pyroclastic vents in Mercury’s Kipler crater in optical (top) and false-color views from NASA’s MESSENGER spacecraft. Pyroclastic material is in brown-red in the bottom image. The vents were likely too fragile to survive the impact of the crater, scientists said, showing that they likely arose after the impact occurred. Credit: Brown University/NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The vents show up along with deposits of pyroclastic ash, which are leftovers of volcanic explosions. This shows that like Earth, the interior of Mercury has volatiles or compounds that have low boiling points. (Earth examples of these are water and carbon dioxide.)

By looking at the pattern of erosion in the craters, Goudge found that there are pyroclastic deposits in craters that are between 1 and 3.5 billion years old. By comparison, Mercury and the rest of the solar system formed about 4.5 billion years ago, and the finding shows the pyroclastic activity happened well after then.

“These ages tell us that Mercury didn’t degas all of its volatiles very early,” Goudge added. “It kept some of its volatiles around to more recent geological times.”

You can read more about the study in the Journal of Geophysical Research.

Source: Brown University

March 16, 2014December 23, 2015 by Jason Major

Mercury Shrinking: the First Rock from the Sun Contracted More than Once Thought

MESSENGER image of Mercury from its third flyby (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

Whatever Mercury’s did to trim down its waistline has worked better than anyone thought — the innermost planet in our Solar System has reduced its radius* by about 7 kilometers (4.4 miles), over double the amount once estimated by scientists.

Of course you wouldn’t want to rush to begin the Mercury diet — its planetary contraction has taken place over the course of 3.8 billion years, since the end of the Late Heavy Bombardment. Still — lookin’ good, Mercury!

These findings come thanks to the MESSENGER spacecraft, in orbit around Mercury since 2011. Now that MESSENGER has successfully mapped literally all of Mercury’s surface, detailed measurements of more than 5,900 landforms created by cooling and contraction of the planet’s crust have allowed researchers to more precisely determine its geologic history and answer some decades-old questions raised by Mariner 10 images.

“This discrepancy between theory and observation, a major puzzle for four decades, has finally been resolved,” said MESSENGER Principal Investigator Sean Solomon. “It is wonderfully affirming to see that our theoretical understanding is at last matched by geological evidence.”

This image shows a long collection of ridges and scarps on the planet Mercury called a fold-and-thrust belt. The belt stretches over 336 miles (540 km). The colors correspond to elevation—yellow-green is high and blue is low. Image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. — This image shows a fold-and-thrust belt stretching over 540 km on Mercury. The colors correspond to elevation— yellow/green is high and blue is low. (Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.)

Using high-definition images acquired with MESSENGER’s MDIS (Mercury Dual Imaging System) instrument, planetary geologist at the Carnegie Institution of Washington and study lead author Paul Byrne and his colleagues identified 5,934 lobate scarps and wrinkle ridges on Mercury that are the result of contraction. From measurements of these features, the team determined that the planet’s radial contraction was much more than that estimated by models based on incomplete imaging from NASA’s Mariner 10 mission — the very first spacecraft to visit (but not orbit) Mercury.

Watch: Fly Across Mercury with MESSENGER!

“These new results resolved a decades-old paradox between thermal history models and estimates of Mercury’s contraction,” said Byrne. “Now the history of heat production and loss and global contraction are consistent.

“Interestingly, our findings are also reminiscent of now-obsolete models for how large-scale geological deformation occurred on Earth when the scientific community thought that the Earth only had one tectonic plate,” Byrne said. “Those models were developed to explain mountain building and tectonic activity in the nineteenth century, before plate tectonics theory.”

Unlike Earth, Mercury has only one global tectonic plate.

The findings were published in the Sunday, March 16 edition of the journal Nature Geoscience.

Source: MESSENGER press release. Read more about tectonic features on Mercury here.

*Mercury’s current radius is 2,440 kilometers (1,516 miles).

February 14, 2014December 29, 2015 by Fraser Cain

Weekly Space Hangout – February 14, 2014: Space Valentines!

Host: Nicole Gugliucci

Astrojournalists: Morgan Rehnberg, Brian Koberlein
Continue reading “Weekly Space Hangout – February 14, 2014: Space Valentines!”

February 3, 2014December 23, 2015 by Elizabeth Howell

Confused Mercury Crater Looks Icy, But May Be Evaporation Evidence

On Mercury, the crater Kertesz pops out in this image taken with NASA's MESSENGER spacecraft. The white you see is shallow irregular depressions, or hollows. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

At first glance, you’d think that white stuff on the floor of Kertesz crater is ice, especially since that substance has been confirmed on its home planet — Mercury. This new shot of the 19-mile (31-kilometer) crater in the Caloris basin shows off irregular depressions, or hollows, that jump out in this color-enhanced picture taken by NASA’s MESSENGER spacecraft. More close-up pictures from previous passes are below the jump.

“The bright material on the floor of Kertész crater is not the water ice recently confirmed to be in craters near Mercury’s poles, but it might well be behaving as ice would on another planet,” NASA wrote in 2012.

“Mercury’s daytime temperatures are so hot at most latitudes that rocks that would be stable at other places in the Solar System may essentially evaporate on Mercury. That is one theory for the formation of these bright, irregular features known as hollows seen here and in many other craters on Mercury.”

There’s still much to learn, so scientists are probably grateful that MESSENGER is still working beyond its design lifetime. It was originally supposed to conclude in 2011, but its mission was extended further to see the effects of the solar maximum on the solar system’s closest planet to the sun.

This photomosaic shows the Kertesz crater on Mercury on the planet's Caloris Basin, as seen by NASA's MESSENGER mission. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — This photomosaic shows the Kertesz crater on Mercury on the planet’s Caloris Basin, as seen by NASA’s MESSENGER mission. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

A side view of Kertész crater on Mercury, as imaged by NASA's MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — A side view of Kertész crater on Mercury, as imaged by NASA’s MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

A 3-D view of Kertesz crater in Mercury's Caloris Basin. Mosaic from NASA's MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — A 3-D view of Kertesz crater in Mercury’s Caloris Basin. Mosaic from NASA’s MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

November 14, 2013December 23, 2015 by Jason Major

Comets Encke and ISON Spotted from Mercury

MESSENGER wide-angle camera images of comets Encke and ISON

Two comets currently on their way toward the Sun have been captured on camera from the innermost planet. The MESSENGER spacecraft in orbit around Mercury has spotted the well-known short-period comet Encke as well as the much-anticipated comet ISON, imaging the progress of each over the course of three days. Both comets will reach perihelion later this month within a week of each other.

While Encke will most likely survive its close encounter to continue along its 3.3-year-long lap around the inner Solar System, the fate of ISON isn’t nearly as certain… but both are making for great photo opportunities!

The figure above shows, on the left, images of comet 2P/Encke on three successive days from Nov. 6 to Nov. 8; on the right, images of C/2012 S1 (ISON) are shown for three successive days from Nov. 9 to Nov. 11. Both appear to brighten a little bit more each day.

MESSENGER image of ISON from Nov. 10 (enlarged detail)

MESSENGER is viewing these comets from a vantage point that is very different from that of observers on Earth. Comet Encke was approximately 0.5 AU from the Sun and 0.2 AU from MESSENGER when these images were taken; the same distances were approximately 0.75 AU and 0.5 AU, respectively, for ISON. More images will be obtained starting on November 16 when the comets should be both brighter and closer to Mercury. (Source: MESSENGER featured image article.)

Encke will reach its perihelion on Nov. 21; ISON on Nov. 28.

“We are thrilled to see that we’ve detected ISON,” said Ron Vervack, of the Johns Hopkins University Applied Physics Laboratory, who is leading MESSENGER’s role in the ISON observation campaign. “The comet hasn’t brightened as quickly as originally predicted, so we wondered how well we would do. Seeing it this early bodes well for our later observations.”

Comet 2P/Encke on October 30, 2013. The coma is partially obscuring the small barred spiral galaxy NGC 4371. Credit and copyright: Damian Peach. — Comet 2P/Encke photographed on October 30 by Damian Peach.

Unlike ISON, Encke has been known for quite a while. It was discovered in 1786 and recognized as a periodic comet in 1819. Its orbital period is 3.3 years — the shortest period of any known comet — and November 21 will mark its 62nd recorded perihelion. (Source)

“Encke has been on our radar for a long time because we’ve realized that it would be crossing MESSENGER’s path in mid-November of this year,” Vervack explained. “And not only crossing it, but coming very close to Mercury.”

These early images of both comets are little more than a few pixels across, Vervack said, but he expects improved images next week when the comets make their closest approaches to MESSENGER and Mercury.

“By next week, we expect Encke to brighten by approximately a factor of 200 as seen from Mercury, and ISON by a factor of 15 or more,” Vervack said. “So we have high hopes for better images and data.”

– Ron Vervack, JHUAPL

Read more about the MESSENGER cometary observation campaign in the full news release here.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute

November 8, 2013December 30, 2015 by Jason Major

Fly Across Mercury with MESSENGER!

Take a ride on the Mercury express and see what MESSENGER sees in these two new videos! Each made from over 280 Narrow-Angle Camera (NAC) images taken at intervals of four seconds, the videos give us a first-class seat on a flight over some of the rugged, sun-scorched surfaces on Mercury’s southern hemisphere.

Check out the second video below:
Continue reading “Fly Across Mercury with MESSENGER!”

October 9, 2013December 23, 2015 by Elizabeth Howell

Could Juno’s Path Near Earth Uncover A Flyby Mystery?

Artist's conception of Juno coming near Earth on a planned flyby Oct. 9, 2013. Credit: NASA

Every so often, engineers send a spacecraft in Earth’s general direction to pick up a speed boost before heading elsewhere. But sometimes, something strange happens — the spacecraft’s speed varies in an unexpected way. Even stranger, this variation happens only during some Earth flybys.

“We detected the flyby anomaly during Rosetta’s first Earth visit in March 2005,” stated Trevor Morley, a flight dynamics specialist at the European Space Agency’s European Space Operations Centre in Darmstadt, Germany.

“Frustratingly, no anomaly was seen during Rosetta’s subsequent Earth flybys in 2007 and 2011. This is a real cosmic mystery that no one has yet figured out.”

The phenomenon has been noticed in several spacecraft (both from ESA and NASA) since 1990. NASA’s NEAR asteroid spacecraft in January 1998 had the largest change, of 13 millimeters (0.5 inches) a second. The smallest variations, with NASA’s Saturn-bound Cassini in 1999 and Mercury-pointing MESSENGER in 2005, were below the threshold of measurement.

ESA won’t even speculate on what’s going on. “The experts are stumped,” the agency says in a press release.

Those experts, however, do have some ideas on how to track that down. ESOC plans to watch Juno’s flyby using a 35 meter deep-space dish in Malargüe, Argentina, as well as a 15-meter dish in Perth, Australia

“The stations will record highly precise radio-signal information that will indicate whether Juno speeds up or slows down more or less than predicted by current theories,” ESA states.

What do you think is going on? Let us know in the comments!

Source: European Space Agency