Category: NASA Space Place

By all outward appearances, the red supergiant appeared normal. But below the surface, hidden from probing eyes, its core had already collapsed into an ultra-dense neutron star, sending a shock wave racing outward from the star’s center at around 50 million kilometers per hour.

The shock wave superheated the plasma in its path to almost a million degrees Kelvin, causing the star to emit high-energy ultraviolet (UV) radiation. About six hours later, the shock wave reached the star’s surface, causing it to explode in a Type IIP supernova named SNLS-04D2dc.

Long before the explosion’s visible light was detected by telescopes on Earth, NASA’s Galaxy Evolution Explorer (GALEX) space telescope captured the earlier pulse of UV light — scientists’ first glimpse of a star entering its death throes.

“This UV light has traveled through the star at the moment of its death but before it was blown apart,â€? explains Kevin Schawinski, the University of Oxford astrophysicist who led the observation. “So this light encodes some information about the state of the star the moment it died.â€?

And that’s exactly why astronomers are so excited. Observing the beautiful nebula left behind by a supernova doesn’t reveal much about what the star was like before it exploded; most of the evidence has been obliterated. Information encoded in these UV “pre-flashesâ€? could offer scientists an unprecedented window into the innards of stars on the verge of exploding.

In this case, Schawinski and his colleagues calculated that just before its death, the star was 500 to 1000 times larger in diameter than our sun, confirming that the star was in fact a red supergiant. “We’ve been able to tell you the size of a star that died in a galaxy several billion light-years away,â€? Schawinski marvels.

“GALEX has played a very important role in actually seeing this for a few reasons,â€? Schawinski says. First, GALEX is a space telescope, so it can see far-UV light that’s blocked by Earth’s atmosphere.

Also, GALEX is designed to take a broad view of the sky. Its relatively small 20-inch primary mirror gives it a wide, 1.2-degree field of view, making it more likely to catch the UV flash preceding a supernova.

With these advantages, GALEX is uniquely equipped to catch a supernova before it explodes. “Just when we like to see it,â€? Schawinski says.

For more information, visit www.galex.caltech.edu, “Ultraviolet Gives View Inside Real ‘Death Star’.â€? Kids can check out how to make a mobile of glittering galaxies at spaceplace.nasa.gov/en/kids/galex_make1.shtml .

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Caption:

Sequence of images shows supernova start to finish. The top left image shows the galaxy before the supernova. At top right, the bright UV flash called the shock breakout indicates a red supergiant has collapsed. At bottom left, moments later, the flash is mostly gone. As the debris expands, it heats up again and becomes brighter (bottom right). The supernova became 10 times the size of the original over the following few days, thus becoming visible to supernova hunters.

By Dr. Tony Phillips

Congratulations!  You’re an oceanographer and you’ve just received a big grant to investigate the Pacific Ocean.  Your task: Map the mighty Pacific’s wind and waves, monitor its deep currents, and keep track of continent-sized temperature oscillations that shape weather around the world. Funds are available and you may start immediately.

Oh, there’s just one problem:  You’ve got to do this work using no more than one ocean buoy.

“That would be impossible,â€? says Dr. Guan Le of the Goddard Space Flight Center.  “The Pacific’s too big to understand by studying just one location.â€?

Yet, for Le and her space scientist colleagues, this was exactly what they have been expected to accomplish in their own studies of Earth’s magnetosphere.  The                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 magnetosphere is an “oceanâ€? of magnetism and plasma surrounding our planet.  Its shores are defined by the outer bounds of Earth’s magnetic field and it contains a bewildering mix of matter-energy waves, electrical currents and plasma oscillations spread across a volume billions of times greater than the Pacific Ocean itself.

“For many years we’ve struggled to understand the magnetosphere using mostly single spacecraft,â€? says Le. “To really make progress, we need many spacecraft spread through the magnetosphere, working together to understand the whole.â€?

Enter Space Technology 5.

In March 2006 NASA launched a trio of experimental satellites to see what three “buoysâ€? could accomplish.  Because they weighed only 55 lbs. apiece and measured not much larger than a birthday cake, the three ST5 “micro-satellitesâ€? fit onboard a single Pegasus rocket.  Above Earth’s atmosphere, the three were flung like Frisbees from the rocket’s body into the magnetosphere by a revolutionary micro-satellite launcher.

Space Technology 5 is a mission of NASA’s New Millennium Program, which tests innovative technologies for use on future space missions.  The 90-day flight of ST5 validated several devices crucial to space buoys: miniature magnetometers, high-efficiency solar arrays, and some strange-looking but effective micro-antennas designed from principles of Darwinian evolution.  Also, ST5 showed that three satellites could maneuver together as a “constellation,â€? spreading out to measure complex fields and currents.

“ST5 was able to measure the motion and thickness of current sheets in the magnetosphere,â€? says Le, the mission’s project scientist at Goddard.  “This could not have been done with a single spacecraft, no matter how capable.â€?

The ST5 mission is finished but the technology it tested will key future studies of the magnetosphere.  Thanks to ST5, hopes Le, lonely buoys will soon be a thing of the past.

Learn more about ST5’s miniaturized technologies at nmp.nasa.gov/st5. Kids (and grownups) can get a better understanding of the artificial evolutionary process used to design ST5’s antennas at spaceplace.nasa.gov/en/kids/st5/emoticon.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

 

Caption:

The Space Technology 5 micro-satellites proved the feasibility of using a constellation of small spacecraft with miniature magnetometers to study Earth’s magnetosphere.

It’s 10 o’clock, and do you know where your Oriental Honey Buzzard is?

Tracking the whereabouts of birds and other migrating wildlife across thousands of miles of land, air, and sea is no easy feat. Yet to protect the habitats of endangered species, scientists need to know where these roving animals go during their seasonal travels.

Rather than chasing these animals around the globe, a growing number of scientists are leveraging the bird’s-eye view of orbiting satellites to easily monitor animals’ movements anywhere in the world.

The system piggybacks on weather satellites called Polar Operational Environmental Satellites, which are operated by the National Oceanic and Atmospheric Administration (NOAA), as well as a European satellite called MetOp. Sensors aboard these satellites pick up signals beamed from portable transmitters on the Earth’s surface, 850 kilometers below. NOAA began the project—called Argos—in cooperation with NASA and the French space agency (CNES) in 1974. At that time, scientists placed these transmitters primarily on buoys and balloons to study the oceans and atmosphere. As electronics shrank and new satellites’ sensors became more sensitive, the transmitters became small and light enough by the 1990s that scientists could mount them safely on animals. Yes, even on birds like the Oriental Honey Buzzard.

“Scientists just never had the capability of doing this before,â€? says Christopher O’Connors, Program Manager for Argos at NOAA.

Today, transmitters weigh as little as 1/20th of a pound and require a fraction of a watt of power. The satellites can detect these feeble signals in part because the transmitters broadcast at frequencies between 401 and 403 MHz, a part of the spectrum reserved for environmental uses. That way there’s very little interference from other sources of radio noise.

“Argos is being used more and more for animal tracking,â€? O’Connors says. More than 17,000 transmitters are currently being tracked by Argos, and almost 4,000 of them are on wildlife. “The animal research has been the most interesting area in terms of innovative science.â€?

For example, researchers in Japan used Argos to track endangered Grey-faced Buzzards and Oriental Honey Buzzards for thousands of kilometers along the birds’ migrations through Japan and Southeast Asia. Scientists have also mapped the movements of loggerhead sea turtles off the west coast of Africa. Other studies have documented migrations of wood storks, Malaysian elephants, porcupine caribou, right whales, and walruses, to name a few.

Argos data is available online at www.argos-system.org, so every evening, scientists can check the whereabouts of all their herds, schools, and flocks. Kids can learn about some of these endangered species and play a memory game with them at spaceplace.nasa.gov/en/kids/poes_tracking.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.