NASA’s Mercury-exploring spacecraft MESSENGER has one more job – crash its 1,100lb body into the planet on April 30, ending one of the most successful scientific explorations in the space agency’s history.
Messenger is now out of fuel and the Sun's gravity will draw the spacecraft into the planet on April 30, at about 8,750 miles per hour, creating a crater as wide as 52 feet, NASA says. On April 25 MESSENGER was in an orbit with a closest approach of 5.1 miles above the surface of Mercury. With a velocity change of 3.43 miles per hour.
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"Navigating a spacecraft so close to a planet's surface had never been attempted before, but it was a risk worth taking given mission success had already been met, and the novel science observation opportunities available only at such very low altitudes," said Bobby Williams, who leads the KinetX Space Navigation and Flight Dynamics group in a statement.
Launched in 2004, NASA sent its $446 million MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft on a rendevous with Mercury where it beamed never-before-available pictures and data on the planet.
The spacecraft discovered a number of important details about the planet. For example, NASA said observations by the MESSENGER spacecraft have provided compelling support for the 20-year old hypothesis that Mercury hosts abundant water ice and other frozen volatile materials like chlorine in its permanently shadowed polar craters.
This week the University of Michigan asked Jim Raines, University of Michigan research scientist and MESSENGER team member, to help quantify the crash and offer up some insight into the mission. He offered the first six fact and we added a few more from NASA.
1. Meteors with the same mass as MESSENGER (513 kg) slam into Mercury about every month or two, and typically with 10 times the speed and 100 times the energy. The planet doesn’t have a thick atmosphere that would slow down objects headed for the surface.
2. The crater the craft will leave near Mercury’s north pole is predicted to be about 50 feet wide. That’s the width of an NBA basketball court.
3. The 1,131-pound spacecraft will hit with the energy of about a ton of TNT, or the force of a car traveling at about 2,000 mph.
4. At almost 9,000 mph, the craft will be traveling three times faster than a speeding bullet and nearly twelve times the speed of sound.
5. On MESSENGER’s last orbit, it will pass just 900 to 1,800 feet over the planet’s surface. We have buildings that tall on Earth.
6. Nearly 55 percent of MESSENGER’s weight at launch was fuel - which is about to run out.
7. Mercury has a diameter of 3,032 miles, about two-fifths of Earth's diameter. Mercury orbits the sun at an average distance of about 36 million miles (58 million kilometers), compared with about 93 million miles for Earth.
8. Because of Mercury's size and proximity to the brightly shining sun, the planet is often hard to see from the Earth without a telescope. At certain times of the year, Mercury can be seen low in the western sky just after sunset. At other times, it can be seen low in the eastern sky just before sunrise.
9. Mercury travels around the Sun in an oval-shaped orbit. The planet is about 28,580,000 miles from the sun at its closest point, and about 43,380,000 miles from the sun at its farthest point. Mercury is about 48,000,000 miles from Earth at its closest approach.
10. Mercury moves around the Sun faster than any other planet. The ancient Romans named it Mercury in honor of the swift messenger of their gods. Mercury travels about 30 miles per second, and goes around the sun once every 88 Earth days. The Earth goes around the sun once every 365 days, or one year.
11. As Mercury moves around the Sun, it rotates on its axis, an imaginary line that runs through its center. The planet rotates once about every 59 Earth days -- a rotation slower than that of any other planet except Venus. As a result of the planet's slow rotation on its axis and rapid movement around the Sun, a day on Mercury -- that is, the interval between one sunrise and the next -- lasts 176 Earth days.
12. MESSENGER is only the second spacecraft sent to Mercury. Mariner 10 flew past it three times in 1974 and 1975 and gathered detailed data on less than half the surface. MESSENGER took advantage of an ingenious trajectory design, lightweight materials, and miniaturization of electronics, all developed in the three decades since Mariner 10 flew past Mercury.
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