3:08:00 PM

Weekend Meteor Shower And ROSAT Orbital Decay Update 21OCT2011

click on image above to view the IMO Live Count during the Orionid Meteor Shower


 Oct. 20, 2011: Earth is about to pass through a stream of debris from Halley's comet, source of the annual Orionid meteor shower.  Forecasters expect more than 15 meteors per hour to fly across the sky on Saturday morning, Oct. 22nd, when the shower peaks.
"Although this isn't the biggest meteor shower of the year, it's definitely worth waking up for," says Bill Cooke of the NASA Meteoroid Environment Office. "The setting is dynamite."
Orionids are framed by some of the brightest and most beautiful constellations in the night sky. The meteors emerge from mighty Orion, the shower's glittering namesake.  From there they streak through Taurus the Bull, the twins of Gemini, Leo the Lion, and Canis Major--home to Sirius, the most brilliant star of all.
This year, the Moon and Mars are part of the show.  They'll form two vertices of a celestial triangle in the eastern sky on Saturday morning while the shower is most active; Regulus is the third vertex.  Blue Regulus and red Mars are both approximately of 1st magnitude, so they are easy to see alongside the 35% crescent Moon.  Many Orionids will be diving through the triangle in the hours before dawn.
Cooke's team at the Meteoroid Environment Office will be watching for Orionids that actually hit the Moon.
Cometary debris streams like Halley's are so wide, the whole Earth-Moon system fits inside. So when there is a meteor shower on Earth, there's usually one on the Moon, too.  Unlike Earth, however, the Moon has no atmosphere to intercept meteoroids.  Pieces of debris fall all the way to the surface and explode where they hit.  Flashes of light caused by thermal heating of lunar rocks and moondust are so bright, they can sometimes be seen through backyard-class telescopes.

A map of the morning sky on Saturday, Oct. 22nd at 5:30 a.m. local time, viewed facing southeast. CLICK HERE to view a larger, more complete map.

"Since we began our monitoring program in 2005, our group has detected more than 250 lunar meteors," says Cooke. "Some explode with energies exceeding hundreds of pounds of TNT."
So far, they've seen 15 Orionids hitting the Moon--"two in 2007, four in 2008, and nine in 2009," recalls Cooke.  This year they hope to add to the haul.  About 25% of the Moon's dark terrain will be exposed to Halley's debris stream, giving the team millions of square miles to scan for explosions.
Watching meteoroids hit the Moon is a good way to learn about the structure of comet debris streams and the energy of the particles therein.  It also allows Cooke and colleagues to calculate risk factors for astronauts who, someday, will walk on the lunar surface again.
"Going outside to watch the Orionids might not be a good idea for a moonwalker," says Cooke.
But it is a good idea for the rest of us.  Set your alarm for a few hours before dawn on Saturday morning and enjoy the show.

Author: Dr. Tony Phillips | Credit: Science@NASA

CLICK HERE To Check For ROSAT and Other Satellite Fly-overs Coming To Your Sky

Doomed German Satellite to Fall to Earth This Weekend

Upcoming Reentry – ROSAT

Type: ROSAT Satellite
Int’l Designation: 1990 049A
Launched: 01 JUN 1990 @ 21:48 UTC
Site: Cape Canaveral Air Force Station LC-17A
Mission: Röntgen X-ray observatory

Reentry Prediction:

Predicted Reentry Time: 23 OCT 2011 @ 13:24 UTC ± 16 hours
Prediction Epoch: 20 OCT 2011 @ 19:36:13.233 UTC
Prediction Ground Track:

(To calculate the time conversion from UTC in your location, view the time zone chart).

For clarity, ground track plot is limited to ± 6 hours
Yellow Icon – location of object at predicted reentry time
Orange Line – area of visibility at the predicted reentry time for a ground observer
Blue Line – ground track uncertainty prior to predicted reentry time (ticks at 5-minute intervals)
Yellow Line – ground track uncertainty after predicted reentry time (ticks at 5-minute intervals)
White Line – day/night divider at predicted reentry time (Sun location shown by White Icon)
Note: Possible reentry locations lie anywhere along the blue and yellow ground track.

About Reentry Predictions

CORDS provides predicted reentry times for satellites and substantial space hardware such as launch stages and payload platforms. The focus is on objects which are reentering as a result of natural orbit decay, not objects which are intentionally deorbited.
Prediction reentry times and locations are updated daily within the final five days of orbit life.
The information provided for each reentry includes a map showing the ground track of the object. The ground track highlights the location along the earth’s surface where the reentry is expected to occur and where a ground-based observer might see the object as it breaks apart because of atmospheric heating and loads.
This map is created by locating the vehicle in orbit at the predicted reentry time and extending the ground track forward and backward in time, consistent with the estimated error in the prediction. The map indicates the final reentry location as reported by eyewitness sightings, when available.
It should be noted that, in general, reentry predictions can be expected to be in error by 10% or more; thus, there is substantial uncertainty as to where reentry will actually occur. Once it does occur, debris will spread over a long track on the ground.
Hazard to people or property from reentering space hardware is very limited. No known reports of death from such events have ever been received.

NOTICE: The materials about Reentry Predictions are for informational purposes only and should not be used as a substitute for specific technical advice or opinions related to your particular facts and circumstances.

1 comment:

Rahul said...

Can these satellites be directed away from Earth, with balance fuel on-board, when they become defunct?
If at all satellite can be guided away from earth, into vast space, with balance fuel, it will make life of humans tension free

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