The ESA’s BepiColombo mission blasted off over the weekend on its way to Mercury, but it’s not the first spacecraft to explore the small planet closest to the Sun.
The first, Mariner 10, swung past Mercury three times in 1974 and 1975 on a test drive for the gravity-assist maneuver that would later help slingshot the Voyager probes (and eventually Galileo and Cassini) toward the outer solar system. As Mariner 10 swept past Venus, the planet’s gravity nudged the spacecraft onto an orbit that would carry it closer to the Sun. On that orbit, Mariner 10 swept past Mercury in March of 1974 for humanity’s first close look at the innermost planet (in space, of course, close is a relative term which in this case means about 700 km). We knew so little about Mercury back then that NASA engineers had to base their orbital calculations on rough estimates of the planet’s actual mass.
Mariner 10 passed Mercury again on September 21, 1974, at a much more distant 48,000 km, then came around for a final close pass at about 330 km on March 16,1975 On those three passes, the probe’s cameras took 2,800 photographs of the rocky, cratered surface. Meanwhile, an ultraviolet spectrometer searched for signs of an atmosphere — and it found one, a thin layer of mostly helium, clinging to the planet in the shelter of its magnetic field. A plasma detector aboard the spacecraft observed how the solar wind interacted with Mercury’s magnetic field, and combined with magnetometer readings, that gave scientists new insight into Mercury’s inner workings. In particular, it confirmed the presence of a large iron core at the heart of the planet. And by measuring infrared radiation from the rocky surface, scientists calculated the temperature on the ground and how much heat Mercury radiated back to space. That, in turn, offered some clues about what Mercury’s surface was made of.
Today, Mariner 10 is probably still drifting around the Sun, nearly crossing paths with Mercury once an orbit, unless it’s collided with an asteroid or been nudged off-course by the gravity of something bigger. But no one has seen or heard from the probe since March 24, 1975, just a week after its last fly-by. That’s when the probe’s nitrogen maneuvering gas finally ran out, and NASA turned off the transmitter and turned its attention to the mountains of data Mariner 10 had sent home.
Messenger to Mercury
Eventually, that data helped plan a return mission to Mercury. The Messenger spacecraft reached Mercury in March 2011 after more than six years of slingshot maneuvers through the inner solar system, and it did something no spacecraft had ever done before: it actually entered Mercury’s orbit. And there it stayed for the next four years.
Messenger mapped the planet’s entire surface at a resolution of 250 km per pixel, zooming in on the most interesting areas of the alien landscape at a higher resolution of 20 km to 50 km per pixel. Those images, combined with a laser altimeter, gave scientists back home on Earth a detailed model of Mercury’s inhospitable terrain. Along with its more modern cameras, Messenger carried three spectrometers for studying the makeup of Mercury’s rocky, scarred surface in different spectra, along with others to study the composition of its thin atmosphere and even the energetic particles in its magnetosphere. A radio instrument measured slight changes in Messenger’s path as it orbited the rocky planet, which scientists used to work out more details about Mercury’s gravity.
And Messenger discovered something utterly unexpected on the world next door to the Sun: ice. Frozen water lies in the cool darkness of some of Mercury’s deepest craters, whose walls tower so high and steep that parts of their floors dwell in permanent shadow. In early 2015, during the mission’s final weeks, when operators felt they had little to lose, Messenger’s orbit swept dangerously close to Mercury’s surface to give its spectrometers a better look at its surprising find.
In the end, of course, Messenger’s maneuvering fuel ran out, and the spacecraft finally succumbed to Mercury’s gravity. It crashed on April 30, 2015, somewhere on the far side of the planet from Earth, where its operators couldn’t hear it die. The spacecraft simply passed around the curve of the planet and never re-emerged.
A New Mission On The Way
BepiColombo may give us another look at what’s left of Messenger, and the dead spaceship may still have things to teach us about Mercury. Solar wind, cosmic radiation, and tiny chunks of rock and dust called micrometeorites slowly wear away materials exposed in space — or on the surface of planets like Mercury, whose thin atmosphere leaves its surface relatively exposed to what scientists call space weathering. Since we know exactly how long Messenger has been lying around on Mercury’s surface, any images BepiColombo sends home can help us understand the rate of space weathering on Mercury. That reveals new detail about the environment on one of the least-understood worlds in our solar system, but it also may help with the design of structures and materials for future spacecraft — or, someday, a crewed Mars mission.
And if things had gone differently, Messenger might not have been alone on Mercury’s surface. The original design for the mission included a disc-shaped lander called the Mercury Surface Element, which would have brought an instrument package, a soil probe, and an adorable micro-rover to the surface. But the ESA cancelled funding for the lander in 2005.
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The ESA’s BepiColombo objective launched over the weekend on its method to Mercury, however it’s not the very first spacecraft to check out the little world closest to the Sun.
The very first, Mariner 10, swung previous Mercury 3 times in 1974 and 1975 on a test drive for the gravity-assist maneuver that would later on assist slingshot the Voyager probes (and ultimately Galileo and Cassini) towards the external planetary system. As Mariner 10 swept previous Venus, the world’s gravity pushed the spacecraft onto an orbit that would bring it closer to the Sun. On that orbit, Mariner 10 swept previous Mercury in March of 1974 for mankind’s very first close take a look at the inner world (in area, naturally, close is a relative term which in this case indicates about 700 km). We understood so little about Mercury at that time that NASA engineers needed to base their orbital estimations on rough price quotes of the world’s real mass.
Mariner 10 passed Mercury once again on September 21, 1974, at a a lot more remote 48,000 km, then occurred for a last close pass at about 330 km on March 16,1975 On those 3 passes, the probe’s video cameras took 2,800 photos of the rocky, cratered surface area. On the other hand, an ultraviolet spectrometer looked for indications of an environment– and it discovered one, a thin layer of primarily helium, holding on to the world in the shelter of its electromagnetic field. A plasma detector aboard the spacecraft observed how the solar wind connected with Mercury’s electromagnetic field, and integrated with magnetometer readings, that offered researchers brand-new insight into Mercury’s inner functions. In specific, it validated the existence of a big iron core at the heart of the world. And by determining infrared radiation from the rocky surface area, researchers computed the temperature level on the ground and just how much heat Mercury radiated back to area. That, in turn, provided some ideas about what Mercury’s surface area was made from.
Today, Mariner 10 is most likely still wandering around the Sun, almost crossing courses with Mercury as soon as an orbit, unless it’s hit an asteroid or been pushed off-course by the gravity of something larger. However nobody has actually seen or spoken with the probe because March 24, 1975, simply a week after its last fly-by. That’s when the probe’s nitrogen maneuvering gas lastly went out, and NASA shut off the transmitter and turned its attention to the mountains of information Mariner 10 had actually sent out house.
(************ ) Messenger to Mercury(********** )
Ultimately, that information assisted prepare a return objective to Mercury. The Messenger spacecraft reached Mercury in March 2011 after more than 6 years of slingshot maneuvers through the inner planetary system, and it did something no spacecraft had actually ever done prior to: it in fact went into Mercury’s orbit. And there it remained for the next 4 years.
Messenger mapped the world’s whole surface area at a resolution of 250 km per pixel, focusing on the most fascinating locations of the alien landscape at a greater resolution of 20 km to 50 km per pixel. Those images, integrated with a laser altimeter, offered researchers back house in the world an in-depth design of Mercury’s unwelcoming surface. In addition to its more contemporary video cameras, Messenger brought 3 spectrometers for studying the makeup of Mercury’s rocky, scarred surface area in various spectra, together with others to study the structure of its thin environment and even the energetic particles in its magnetosphere. A radio instrument determined minor modifications in Messenger’s course as it orbited the rocky world, which researchers utilized to exercise more information about Mercury’s gravity.