March 7, 2013 | 1
[The text below is a modified transcript of this video.]
5) Mercury’s Magma Ocean
Mercury may once have contained a veritable ocean of shifting, glowing molten rock. Scientists think magma flowed over the planet’s surface more than four billion years ago.
Since March 2011, NASA’s Messenger probe has been orbiting Mercury to gather information about the planet. Messenger’s observations reveal two different types of rocks, with distinct chemical compositions.
To find out how Mercury’s rocks formed, scientists reconstructed the minerals in a lab (preview) here on Earth. Their experiments suggest the rocks originated in an ocean of magma. The magma settled into two layers, solidified, and then erupted back out onto the planet’s surface, leaving behind two distinct rock types. The whole process must have occurred shortly after Mercury’s formation, about 4.5 billion years ago.
4) Flinging Space Trash
NASA estimates we now have 500,000 pieces of space junk whizzing around our planet.
Larger than a marble and traveling at speeds of up to 15,000 miles per hour, all that junk spells danger for both astronauts and satellites. Check out this hole punched through a radiator panel of the Space Shuttle Endeavour back in 2007. The wall of the radiator is solid aluminum, half an inch thick.
The latest idea for getting rid of our space trash uses the debris own momentum as a way to get around. The TAMU Space Sweeper with Sling-Sat uses two receiver cups to catch junk. Its retractable arms then change the direction of the incoming object, firing it downward into Earth’s atmosphere where it can burn up.
The beauty of this idea is the Sling-Sat can use the momentum transferred from the trash as a push-off toward its next target. According to its inventors, two engineers at Texas A&M University, this method allows the sling-sat to be smaller & more efficient and would extend its lifespan compared to a regular satellite (pdf).
3) Spectacular Solar Images
Three years ago, NASA launched the Solar Dynamics Observatory, a program to study the sun’s magnetic field and its effect on the earth. Recent data acquired from the observatory show several coronal mass ejections and solar eruptions. But no need to be alarmed, this doesn’t pose any major threat to us. For now, just sit back and watch the spectacular images (see video above).
2) Van Allen’s Third Belt
A new Van Allen radiation belt appeared and then disappeared from Earth’s orbit. Turns out the solar wind can really ruffle these rings.
The Van Allen radiation belts are two rings of charged particles, held in orbit around Earth by our planet’s magnetic field. Last September, NASA’s twin Radiation Storm Probes launched and began to examine the rings, recording their structure. But a couple days later, they revealed a third ring between the inner and outer belts.
Scientists think a burst of solar wind sent a shock wave through the belts, destroying part of the outer ring and splitting the leftovers in two–for a total of three belts. And the disturbances weren’t over yet. Another shock wave blasted through in October, destroying both outer rings. That left a single radiation belt, but not for long. About a week later, a third wave coasted by and restored the original two belts.
If these solar disturbances are as common as they seem, scientists will have to revamp their model of the Van Allen radiation belts.
You can check out the full study in the February 28 edition of Science (preview).
1) Massive Black Hole Spins Near Light-Speed
A super-massive black hole, a few million times more massive than our sun, has a super spin as well: it whirls around at close to the speed of light!
Spiral galaxy NGC 1365 contains an enormous black hole more than three million kilometers across. Supermassive black holes are so big their gravity pulls in surrounding matter, creating a flat accretion disk. Those disks reflect x-ray light we can detect with instruments like NASA’s NuSTAR and the European Space Agency’s XMM-Newton.
The black hole’s spin affects this light, because faster-spinning holes pull their accretion disks closer. The closer the disk is to the black hole, the more it feels the effects of its gravitational pull—and the more warped its reflected x-rays become.
Data from XMM-Newton and NuStar reveal X-rays from NGC 1365′s black hole are super-warped. This means the black hole must be spinning incredibly fast, with its surface traveling at near light-speed.
The fast spin suggests that this black hole acquired its super-mass and its super-spin from one huge merger, or from a stable accretion disk. If it had picked up its mass in bits and pieces, each piece would have changed the hole’s momentum instead of contributing to a steady spin in a single direction.
You can read more in the February 27 edition of Nature. (Scientific American is part of Nature Publishing Group.)
—Portions of the script above written by Sophie Bushwick, Eric R. Olson & Isha Soni