10 Important Facts about NASAs Falling UARS Satellite

10 Important Facts about NASAs Falling UARS Satellite

Updated on Sunday, September 25, 2011 – 3.45 PM IST

Updated – Wednesday, September 28, 2011
Not in Canada Nasa's UARS spacecraft fell to Earth to the north-east of the Vanuatu archipelago.


NASA UARS UPDATE 10
Update #10
Fri, 23 Sep 2011 08:15:08 PM GMT+0530
As of 10:30 a.m. EDT on Sept. 23, 2011, the orbit of UARS was 100 miles by 105 miles (160 km by 170 km).
Re-entry is expected late Friday, Sept. 23, or early Saturday, Sept. 24, Eastern Daylight Time. Solar activity is no longer the major factor in the satellite’s rate of descent. The satellite’s orientation or configuration apparently has changed, and that is now slowing its descent. There is a low probability any debris that survives re-entry will land in the United States, but the possibility cannot be discounted because of this changing rate of descent. It is still too early to predict the time and location of re-entry with any certainty, but predictions will become more refined in the next 12 to 18 hours.

NASA update regarding UARS satellite
Update #8
Thu, 22 Sep 2011 05:14:51 PM GMT+0530

As of 7 a.m. EDT Sept. 22, 2011, the orbit of UARS was 115 mi by 120 mi (185 km by 195 km). Re-entry is expected sometime during the afternoon of Sept. 23, Eastern Daylight Time. The satellite will not be passing over North America during that time period. It is still too early to predict the time and location of re-entry with any more certainty, but predictions will become more refined in the next 24 to 36 hours.

Why UARS is falling or coming back to Earth?


Generally, satellites in Earth orbit naturally lose altitude slowly over time if they have no fuel to boost to higher orbit.

The orbit of UARS has slowly decayed over the years following its deactivation, to the point that it will soon begin its final dive toward the ground, pulled in by gravity.

How much of UARS will break up during re-entry?

The spacecraft will break into pieces as it plummets through the atmosphere, but not all of it will burn up in the heat of re-entry. One analysis of the spacecraft suggests that of its total 6 1/2-ton bulk, only 1,170 pounds (532 kilograms) will survive when it reaches the ground.

Will UARS pose a risk to people on the earth ,on the ground?

Although most of the spacecraft will be destroyed during re-entry, some will survive.
These pieces of debris could pose a small risk of damaging property or endangering people when they fall.
"The risk to public safety or property is extremely small, and safety is NASA's top priority," NASA said in a statement.


1.
The spacecraft, called the Upper Atmosphere Research Satellite (UARS), is a 6 1/2-ton behemoth that will likely break up as it burns through the atmosphere on its trip down.

2.
UARS is a NASA Earth-observation satellite. The spacecraft was designed to measure ozone and other chemical compounds found in Earth's ozone layer. UARS also measured winds and temperatures in the stratosphere, as well as the energy Earth received from the sun.

3.
The bus-size UARS satellite is about 35 feet (10.7 meters) long and 15 feet (4.5 m) wide.

4.
UARS launched aboard NASA's space shuttle Discovery, which deployed it into orbit on Sept. 15, 1991. It was originally designed to operate for only three years.

5.
UARS conducted scientific research for 14 years.

6.
According to NASA reports During it active mission, the UARS satellite soared above Earth at an altitude of about 375 miles (600 km)

7.
Its orbital path was tilted about 57 degrees with respect to Earth's equator.

8.
According to NASA UARS was officially decommissioned on Dec. 14, 2005. At that point, six of its 10 scientific instruments were still functioning. The spacecraft made one final engine burn to lower its orbit out of the way of useful satellites, and its systems were commanded into a non-active mode.

9.
As of Sept. 8, 2011, the orbit of UARS was 152 miles by 171 miles (245 km by 275 km) with an inclination of 57 degrees. Because the satellite's orbit is inclined 57 degrees to the equator, any surviving components of UARS will land within a zone between 57 degrees north latitude and 57 degrees south latitude. It is impossible to pinpoint just where in that zone the debris will land, but NASA estimates the debris footprint will be about 500 miles long.

10.
According to NASA If you find something you think may be a piece of UARS, do not touch it. Contact a local law enforcement official for assistance.

Updated on Sunday, September 25, 2011 – 3.45 PM IST

NASA's UARS Re-enters Earth's Atmosphere

NASA’s decommissioned Upper Atmosphere Research Satellite (UARS) fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. Sept. 24, 20 years and nine days after its launch on a 14-year mission that produced some of the first long-term records of chemicals in the atmosphere.

The precise re-entry time and location of debris impacts have not been determined. During the re-entry period, the satellite passed from the east coast of Africa over the Indian Ocean, then the Pacific Ocean, then across northern Canada, then across the northern Atlantic Ocean, to a point over West Africa. The vast majority of the orbital transit was over water, with some flight over northern Canada and West Africa.

Six years after the end of its productive scientific life, UARS broke into pieces during re-entry, and most of it up burned in the atmosphere. Data indicates the satellite likely broke apart and landed in the Pacific Ocean far off the U.S. coast. Twenty-six satellite components, weighing a total of about 1,200 pounds, could have survived the fiery re-entry and reach the surface of Earth. However, NASA is not aware of any reports of injury or property damage.

The Operations Center for JFCC-Space, the Joint Functional Component Command at Vandenberg Air Force Base, Calif., which works around the clock detecting, identifying and tracking all man-made objects in Earth orbit, tracked the movements of UARS through the satellite’s final orbits and provided confirmation of re-entry.

“We extend our appreciation to the Joint Space Operations Center for monitoring UARS not only this past week but also throughout its entire 20 years on orbit,” said Nick Johnson, NASA’s chief scientist for orbital debris, at NASA’s Johnson Space Center in Houston. “This was not an easy re-entry to predict because of the natural forces acting on the satellite as its orbit decayed. Space-faring nations around the world also were monitoring the satellite’s descent in the last two hours and all the predictions were well within the range estimated by JSpOC.”

UARS was launched Sept. 12, 1991, aboard space shuttle mission STS-48 and deployed on Sept. 15, 1991. It was the first multi-instrumented satellite to observe numerous chemical components of the atmosphere for better understanding of photochemistry. UARS data marked the beginning of many long-term records for key chemicals in the atmosphere. The satellite also provided key data on the amount of light that comes from the sun at ultraviolet and visible wavelengths. UARS ceased its scientific life in 2005.

Because of the satellite's orbit, any surviving components of UARS should have landed within a zone between 57 degrees north latitude and 57 degrees south latitude. It is impossible to pinpoint just where in that zone the debris landed, but NASA estimates the debris footprint to be about 500 miles long.

NASA and the Joint Space Operations Center of U.S. Strategic Command at Vandenberg Air Force Base in California is releasing updates.

Updated – Wednesday, September 28, 2011
Not in Canada Nasa's UARS spacecraft fell to Earth to the north-east of the Vanuatu archipelago.

NASA’s decommissioned Upper Atmosphere Research Satellite fell back to Earth at 12 a.m. EDT (0400 GMT), as Friday, Sept. 23, turned to Saturday, Sept. 24 on the United States east coast. The Joint Space Operations Center at Vandenberg Air Force Base in California has determined the satellite entered the atmosphere over the Pacific Ocean at 14.1 degrees south latitude and 189.8 degrees east longitude (170.2 west longitude). This location is over a broad, remote ocean area in the Southern Hemisphere, far from any major land mass. The debris field is located between 300 miles and 800 miles downrange, or generally northeast of the re-entry point. NASA is not aware of any possible debris sightings from this geographic area.

How did NASA know that UARS was back?
To find out if a satellite is no longer in orbit, scientists send out sensors.
If you don't get a response back, that's a good indication that it has re-entered the Earth's atmosphere.
Typically, scientists will try sending out these sensors at least three times just to make sure the data is accurate. That can take between two and three hours.



NASA is posting updates at its UARS mission website
http://www.nasa.gov/mission_pages/uars/index.html

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