Kill The Messenger: NASA Orbiter Set To Crash Into Mercury Thursday

Composite image of the surface of Mercury
In 2013, Messenger finished imaging the entire surface of Mercury. This composite image was created from thousands of images. (Image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

After 4,104 orbits of Mercury and billions of miles of space travel, NASA’s Messenger orbiter will end its mission with a quiet bang Thursday. Messenger will crash into the planet it’s been orbiting for four years.

NASA says the orbiter will begin the process of lithobraking at 3:26 p.m. ET — meaning that Messenger will essentially scrape to a stop after hitting the planet’s surface traveling at thousands of miles an hour. The Oxford English Dictionary reminds us that litho is the combining form for the Greek word for “stone.”

Messenger was launched from Earth back in 2004. And now, after studying Mercury’s craters, it will make a new one — NASA says it impact crater should be around 52 feet wide.

This image of a "red spot" on Mercury that is thought to be the result of a volcanic explosion was sent to Earth by the Messenger probe back in 2011. (Image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)
This image of a “red spot” on Mercury that is thought to be the result of a volcanic explosion was sent to Earth by the Messenger probe back in 2011. (Image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

“Orbiting Mercury is really tough, because it’s so close to the sun,” NPR’s Geoff Brumfiel reports. “The sun’s gravity is actually pulling the Messenger spacecraft into the planet. Messenger has used its engines to push itself away– but now those engines are out of fuel, so it’s going to plow into Mercury at over 8,000 miles per hour.”

The orbiter has added a wealth of research to the data gleaned by Earth’s first probe to visit Mercury — the Mariner 10, which launched back in 1973 and performed a flyby two years later.

Geoff says, “I think we can call this mission a big success – it spent four years gathering really good data about the planet. It gave us our first solid maps of Mercury, and it provided evidence for water on its surface, which is really surprising, given how hot Mercury is.”

NASA says the orbiter has sent back more than 255,000 images to Earth, and that it created more than 10 terabytes of data that have been publicly released. One of those images included Mercury’s neighbors.

Messenger sent this "family portrait" of the planets in the solar system, created from 34 images. (Image courtesy NASA)
Messenger sent this “family portrait” of the planets in the solar system, created from 34 images. (Image courtesy NASA)

Messenger’s name is shorthand for its official title: the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. It has its own Twitter feed, which will likely go dark sometime today.

NASA Mission Systems Engineer Dan O’Shaughnessy tells Air and Space that researchers have been squeezing the last bits of usefulness out of the Messenger mission — particularly as the craft has gotten closer to Mercury’s surface in recent weeks.

The terminal impact will be hidden from Earth’s view. With no other craft nearby to witness its final seconds, NASA officials say they’ll know Messenger is no more when it can no longer track the orbiter.

“We’ll just be looking for a signal, and the absence of signal will sort of confirm our demise,” O’Shaughnessy tells Air and Space.

As Scott reported for the Two-Way earlier this month, Messenger will join the elite “Touchdown Club” of man-made objects that ended their missions on other planets. Member station KQED has a roundup that includes several objects on the Moon as well as spacecraft on Mars, Venus, and Jupiter, along with the moon Titan, an asteroid and a comet.

Copyright 2015 NPR. To see more, visit http://www.npr.org/.
Read Original Article – Published APRIL 30, 201511:41 AM ET

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