1. Space Debris

2. A Greener Planet?  Every year, in almost every country around the world, people do their part to clean up our Earth.  Recycling programs are everywhere, and whether our involvement is large or small, we all contribute to help make our home a better place.  But what about our Earth’s home? Who is looking out for outer space?  Every year, in almost every country around the world, people do their part to clean up our Earth.  Recycling programs are everywhere, and whether our involvement is large or small, we all contribute to help make our home a better place.  But what about our Earth’s home? Who is looking out for outer space?

4. What is out there?  Space debris is also called orbital debris, space junk and space waste.  It is the man-made objects that are in orbit around the Earth that no longer serve any useful purpose to us.  They can include anything from entire used rocket stages and defunct satellites to explosion fragments, paint flakes, dust, slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites, deliberate insertion of small needles, and other small particles from equipment.  Currently, 200 new objects are added annually.  Space debris is also called orbital debris, space junk and space waste.  It is the man-made objects that are in orbit around the Earth that no longer serve any useful purpose to us.  They can include anything from entire used rocket stages and defunct satellites to explosion fragments, paint flakes, dust, slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites, deliberate insertion of small needles, and other small particles from equipment.  Currently, 200 new objects are added annually.

5. Interesting Facts  In 1999 it was estimated there were 4 million pounds of space junk in low-Earth orbit, made up of 110,000 objects larger than 1 cm. -- large enough to damage a satellite or space-based telescope.  For example, a tiny speck of paint from a satellite dug a pit in a space shuttle window nearly a 1/4 in. wide.  In 1999 it was estimated there were 4 million pounds of space junk in low-Earth orbit, made up of 110,000 objects larger than 1 cm. -- large enough to damage a satellite or space-based telescope.  For example, a tiny speck of paint from a satellite dug a pit in a space shuttle window nearly a 1/4 in. wide.  In 1996, only 2 years after it went up, part of a Pegasus rocket made the most space debris by a spacecraft's destruction. It created a cloud of 300,000 pieces bigger than 4 mm, 700 of which were big enough to be catalogued. This event doubled the Hubble Space Telescope’s collision risk.

6. More Facts…  In 1958, America’s 2nd satellite, Vanguard I went into orbit. It worked for only 6 years, but is still up in space.  The “most dangerous garment in history” orbited with a speed of 28,000 km/h for one month in 1965. Edward White, a Gemini 4 astronaut, lost this glove during the 1st American space walk.  In 1958, America’s 2nd satellite, Vanguard I went into orbit. It worked for only 6 years, but is still up in space.  The “most dangerous garment in history” orbited with a speed of 28,000 km/h for one month in 1965. Edward White, a Gemini 4 astronaut, lost this glove during the 1st American space walk.  The Mir space station sent more than 200 objects into space in its first 10 years of operation. Most of them were garbage bags.  In June 2000, the total number of trackable space objects included 90 space probes, 2,671 satellites and 6,096 pieces of space junk.

7. Why is this bad?  “Sandblasting” or erosive damage, can occur on objects that are both being used and unused when they come into contact with clouds of very small particles in space.  Collisions can be highly damaging to functioning satellites due to the extremely high orbital velocities at which this “junk” travels. Some debris has been recorded moving along at 17,500 mph! Collisions are also known to produce even more space debris.  This is called the Kessler Syndrome.  “Sandblasting” or erosive damage, can occur on objects that are both being used and unused when they come into contact with clouds of very small particles in space.  Collisions can be highly damaging to functioning satellites due to the extremely high orbital velocities at which this “junk” travels. Some debris has been recorded moving along at 17,500 mph! Collisions are also known to produce even more space debris.  This is called the Kessler Syndrome.

8. The Kessler Syndrome  In 1978, a NASA scientist named Donald J. Kessler theorized that the volume of space debris in low earth orbits is so high that objects in orbit are frequently struck by debris.  Unfortunately, this multiplies the amount of debris and amplifies the possibility of further impacts.  Ultimately, the vast amount of debris in orbit could make space exploration, and even the use of satellites, impossible.  In 1978, a NASA scientist named Donald J. Kessler theorized that the volume of space debris in low earth orbits is so high that objects in orbit are frequently struck by debris.  Unfortunately, this multiplies the amount of debris and amplifies the possibility of further impacts.  Ultimately, the vast amount of debris in orbit could make space exploration, and even the use of satellites, impossible.

9. Examples of Debris

10. Collisions in Space  This photo shows the antenna dish of the Hubble Space Telescope which was completely penetrated by space debris.

11. Re-Entry  On 21 January 2001, a Delta 2 third stage, known as a PAM-D reentered the atmosphere over the Middle East. The titanium motor casing of the PAM-D, weighed about 70 kg, & landed in Saudi Arabia about 240 km from the capital of Riyadh.  Parts from the second stage of PAM-D fell in Georgetown & Seguine, TX the following day.  On 21 January 2001, a Delta 2 third stage, known as a PAM-D reentered the atmosphere over the Middle East. The titanium motor casing of the PAM-D, weighed about 70 kg, & landed in Saudi Arabia about 240 km from the capital of Riyadh.  Parts from the second stage of PAM-D fell in Georgetown & Seguine, TX the following day.

12. Possible Solutions

13. Alternate Orbit  Sometimes it would require too much fuel to de-orbit a satellite from its path. In these cases, it can also be brought to an orbit where atmospheric drag would cause it to de- orbit after some years.  This has been done! The French Spot-1 satellite, brought its time to atmospheric reentry down from an estimated 200 years to about 15 years by lowering its perigee from 830 km to about 550 km.  Sometimes it would require too much fuel to de-orbit a satellite from its path. In these cases, it can also be brought to an orbit where atmospheric drag would cause it to de- orbit after some years.  This has been done! The French Spot-1 satellite, brought its time to atmospheric reentry down from an estimated 200 years to about 15 years by lowering its perigee from 830 km to about 550 km.

14. NASA Goddard’s RRM

15. Terminator Tether  When a satellite has completed its task, it could be brought back down to Earth where it could be properly disposed of and/or recycled.  This could be done with the use of a "terminator tether," also called an “electro-dynamic tether” that is rolled out, and slows down the spacecraft.  When a satellite has completed its task, it could be brought back down to Earth where it could be properly disposed of and/or recycled.  This could be done with the use of a "terminator tether," also called an “electro-dynamic tether” that is rolled out, and slows down the spacecraft.

16. Other Debris?  Unfortunately, many other ideas are either too expensive or unrealistic. These involve pulling space debris back into Earth's atmosphere by:  Using laser brooms to vaporize or nudge particles into rapidly-decaying orbits also called the Orion Project  Huge aero-gel blobs to absorb impacting junk and eventually fall out of orbit with them trapped inside  Instead, NASA currently focuses on preventing collisions by keeping track of the larger debris, and preventing more debris from littering space.  Unfortunately, many other ideas are either too expensive or unrealistic. These involve pulling space debris back into Earth's atmosphere by:  Using laser brooms to vaporize or nudge particles into rapidly-decaying orbits also called the Orion Project  Huge aero-gel blobs to absorb impacting junk and eventually fall out of orbit with them trapped inside  Instead, NASA currently focuses on preventing collisions by keeping track of the larger debris, and preventing more debris from littering space.

17. Counter- Claims

18. Counterclaims…  Major Michael Birmingham of the U.S. Space Command reported that 91 objects fell back into the atmosphere in all of 1998, and 69 in 1997.  "Most objects that re-enter the Earth's atmosphere burn-up or re-enter over water," Birmingham said, noting that nearly three- quarters of the planet is wet and a great majority of what's dry is uninhabited.  "Since the space surveillance mission began, almost 17,000 objects that we track re-entered the Earth's atmosphere. Catastrophic re-entries are rare and the exception."  Major Michael Birmingham of the U.S. Space Command reported that 91 objects fell back into the atmosphere in all of 1998, and 69 in 1997.  "Most objects that re-enter the Earth's atmosphere burn-up or re-enter over water," Birmingham said, noting that nearly three- quarters of the planet is wet and a great majority of what's dry is uninhabited.  "Since the space surveillance mission began, almost 17,000 objects that we track re-entered the Earth's atmosphere. Catastrophic re-entries are rare and the exception."

19. Armored Devices  "We get hit regularly on the shuttle," said Joseph Loftus, assistant director of engineering for NASA's Space and Life Science Directorate. "We've replaced more than 80 shuttle windows because of debris impacts."  Because of small collisions, some spacecraft, like the International Space Station, are now armored to mitigate damage from space debris.  "We get hit regularly on the shuttle," said Joseph Loftus, assistant director of engineering for NASA's Space and Life Science Directorate. "We've replaced more than 80 shuttle windows because of debris impacts."  Because of small collisions, some spacecraft, like the International Space Station, are now armored to mitigate damage from space debris.

20. What Do YOU Think?  Is space debris just another over hyped scientific issue, or could this really become a larger problem in the future? Why did you say this?  Should we leave it all up there, or take the time and money to bring it down? Why did you choose this answer?  If any, which of the three possible solutions do you think is the most practical and why?  Why would it be bad if the “Kessler Syndrome” actually happened? What other consequences could it hold for Earth?  Is space debris just another over hyped scientific issue, or could this really become a larger problem in the future? Why did you say this?  Should we leave it all up there, or take the time and money to bring it down? Why did you choose this answer?  If any, which of the three possible solutions do you think is the most practical and why?  Why would it be bad if the “Kessler Syndrome” actually happened? What other consequences could it hold for Earth?

21. Sources  http://www.nasa.gov/  http://www.space.com/spacewatch/space_ju nk.html  http://www.space.com/scienceastronomy/pla netearth/space_junk_000901.html  http://en.wikipedia.org/wiki/Space_debris  http://www.nasa.gov/  http://www.space.com/spacewatch/space_ju nk.html  http://www.space.com/scienceastronomy/pla netearth/space_junk_000901.html  http://en.wikipedia.org/wiki/Space_debris