The document discusses the issue of space debris, describing it as a significant environmental problem affecting space missions today. It details the origins, dangers, and specific events related to space debris, along with various measures proposed and taken to mitigate this growing hazard. The document highlights the necessity for proactive measures to ensure the safety of future space ventures and clean up the existing debris in Earth's orbit.

1. Space Debris
An “environmental” problem for space missions
Assignment as part of CH311
Environmental Science and Engineering
D. Pramod Reddy
(SC12B079)
Avionics
Indian Institute of Space Science and Technology
Thiruvananthapuram
September 2014

2. Acknowledgement
First of all, I would like to thank Dr. KG Sreejalekshmi for her encouragement to study about Space
Debris, which has become the topic of great concern today. I am sure that the study made in this
topic will be of definite help in my future. Next, I would like to thank various sources which provided
me with sufficient references to do this study.

3. Abstract of Study
This assignment gives a detail cover of the topic “Space Debris” which is one of the major
environmental problem for the Space Missions now-a-days. The study goes through the basic
question ---What is Space Debris, why is it dangerous, what are the major events occurred in
corresponding to the space debris, what are the threats for space missions, what are the measures
taken for cleaning up this space junk, ISRO’s concern on this issue and finally concludes with the
need for making our space clean.

4. Contents
What is Space Debris?
Why is Space Debris dangerous?
Space Debris Events
Threat to Space Missions
Measures taken for Cleaning Space Debris
ISRO – Space Debris
Conclusion
Bibliography

5. What is Space Debris?
Space debris, which is also known as orbital debris, space junk or space waste, is the collection of
defunct objects in orbit around Earth. It includes everything from spent rocket stages, old satellites,
and fragments from disintegration, erosion, and collisions.
Space junk got its start in the middle of the twentieth century, at the very beginning of the space
race. When the Soviet Union launched Sputnik I, the first satellite in history to go into orbit around
the Earth, on Oct. 4, 1957, the world paid attention. Although the satellite was small by today's
standards -- it was about the size of a beach ball -- Sputnik still caused a great amount of fear among
nations, especially the United States. Along with sparking the space race, the launch worried many
Americans because of its association with the nuclear arms race. If the Soviets were capable of
putting a satellite into space, they could also strap a nuclear bomb on top and reach a target in a
matter of hours.
Since this caught everyone off guard, several countries threw resources into space programs -- the
event directly led Congress to create the National Aeronautics and Space Administration, or NASA.
Governments, and now cell phone, television and GPS receiver companies, have launched
hundreds of satellites a year since the beginning of the space race. These satellites, along
with rockets and other objects sent up into space, make up the majority of space junk. The “NASA
Orbital Debris Space Program” Office also lists these types of objects as examples of space junk:
 Derelict (abandoned) spacecraft - When spaceships or parts of spaceships no longer work,
they're left to float around space indefinitely. It's usually too expensive to retrieve these objects,
so they're left there to circle the Earth until they fall back down or collide with other space junk.
 Upper stages of launch vehicles - Modern space shuttles are actually a collection of several
rockets stacked on top of each other. When space shuttles launch, it usually takes more than
one rocket boost to get them high enough into space, and these rockets are fired off in stages.
The final stages are called upper stages because they're located near the top of the entire shuttle,
and because they fire so late, any material expelled from the spacecraft can get trapped in the
Earth's orbit. They're among the largest kinds of space junk.
 Solid rocket motor effluents - Some space shuttles use solid rocket fuel for propulsion. After
launches, some fuel can be left over and will float around in whatever container in which it flew
up. This poses a great risk for collisions, because it only creates more space junk after an
explosion.

6. Why is Space Debris dangerous?
The U.S. Space Surveillance Network, a department that tracks debris floating through space and
reports to NASA, observes over 13,000 man-made objects orbiting Earth larger than 4 inches in
diameter [source: National Geographic News]. That number has only been increasing, up from 9,000
objects in 2000. The organization estimates there are also millions of much smaller objects floating
around, and all of it combined weighs about 5,500 tons.
Although it's hard to believe, many of these objects travel around the Earth at speeds more than
22,000 miles an hour. Anything traveling at a velocity this high would cause a considerable amount
of damage to a spacecraft if a direct hit occurred. Even a tiny fleck of paint traveling at such a speed
is capable of boring a quarter-inch hole into the window of a space station.
Image coutesy: NASA
Because there are so many objects flying around up there, there's concern that collisions between
debris will only produce more fragments. Even if we stopped launching spacecraft right now and
didn't send a single object into orbit, the amount of debris in space would remain constant until 2055.
After that, things would actually get worse, because the amount of material already up there would
inevitably collide and create even more space junk. Experts are worried this is already happening.
The most recent case of such a collision, for instance, happened on Jan. 17, 2005, when a piece of
debris from an exploded Chinese rocket smashed into a 31-year-old American rocket that had been
left alone. The collision only produced four pieces of debris, but observers fear it's only a matter of
time before such pieces create an unstoppable chain reaction.

7. Space Debris Events
The space around Earth is a crowded space packed with nearly 22,000 spent rocket stages, dead
or dying satellites and countless crumbs of human-made orbital flotsam. An average of one object
has reentered Earth's atmosphere every day.
Satellite Shootdown: The U.S. Navy intercepted its defunct spy satellite USA-193 on Feb. 20,
2008, sending a trail of debris that some amateur astronomers reported falling over the northwestern
United States and Canada. Department of Defense officials said they hadn't recovered any debris
larger than a football.
Noggin’ Knocker: A woman in Turley, Oklahoma, got a noggin-knock in January 1997 when she
was struck with a lightweight fragment of charred woven material. She was not injured. The sky
junk was identified as debris from a Delta 2 booster, which reentered the Earth's atmosphere on
Jan. 22, 1997. Other debris from that booster included a steel propellant tank and a titanium
pressure sphere.
Mystery Ball: Several mysterious spheres turned up in Australia in the 1960s, with some
speculating these balls could be connected with UFO phenomenon. One such titanium sphere was
spotted in Merkanooka, Western Australia. Dubbed the Merkanooka ball, the metal sphere was later
identified as a tank used for drinking water in the Gemini V spacecraft, which was launched on Aug.
21, 1965, and reentered the atmosphere and splashed down into the Atlantic Ocean on Aug. 29 that
year.
Toxic Touchdown: A secret Soviet-navy satellite called Cosmos 954, which was launched on Sept.
18, 1977, spiraled out of control. The spy radar antennas each sported a compact nuclear reactor,
making the reentry one of the most frightening to date for people on the ground. On Jan. 24,
1978, Cosmos 954 reentered over Canada and shed debris across the frozen ground of the
Canadian Arctic. Following the crash, the U.S. and Canada conducted overflights of the area and
associated cleanup efforts.

8. Desert Dropdown: On Jan. 21, 2001, a Delta 2 third stage, known as a PAM-D (Payload Assist
Module-Delta), reentered the atmosphere over the Middle East. Its titanium motor casing, weighing
about 154 pounds (70 kilograms), slammed down in Saudi Arabia, while a titanium pressurant tank
landed near Seguin, Texas, and the main propellant tank of Delta 2 launch vehicle which landed
Georgetown, Texas on Jan 22, 1997.
Spare Space Parts: In May 1966, spacecraft debris was spotted in the Rio Negro District of Brazil.
The metal parts were identified as coming from a stage of the Saturn development test (SA-5) that
launched in 1964 and which reentered the atmosphere on April 30, 1966. The litter included a piece
of lightweight metal, an oval-shaped chunk of metal, a black beehive-shaped structure and four
pieces of fragile wire.
Columbia Debris: On Feb. 1, 2003, during its return to Earth, Space Shuttle Columbia disintegrated
on reentry, killing seven astronauts. The catastrophic, lethal accident shed thousands of pieces of
debris across a 28,000 square mile (72,520 square kilometers) area in eastern Texas and western
Louisiana. More than 80,000 recovered pieces were stored for follow-up research.
Image Coutesy: NASA

9. Sonic Snow: After completing 51,658 orbits around Earth, the Compton Gamma Ray Observatory
was intentionally deorbited due to a crippled gyroscope on June 4, 2000. As the spacecraft tumbled
through Earth's atmosphere, its solar panels and antennas were thought to pop off first, while other
parts likely melted. About 13,227 pounds (6,000 kilograms) of debris from the observatory splashed
down into the Pacific Ocean southeast of Hawaii.
Russian heavyweight: In the world of space litter, the heavyweight champ would have to be Mir,
heftier in its day than any object (except the moon) to orbit Earth. The 15-year-oldRussian space
station began its suicidal nosedive on March 23, 2001, as it reentered Earth's atmosphere above
the Pacific Ocean near Fiji. Though most of the station, weighing 286,600 pounds (130,000
kilograms), burned up in the atmosphere, about 1,500 fragments reached Earth's surface.
Beachgoers in Nadi, Fiji, snapped photos of blazing bits of Mir debris and there were reports of sonic
booms caused by heavy debris.
Skylab Plummet: Weighing in at 77 tons (70,000 kilograms), the first and only solely-U.S. space
station Skylab launched into orbit on May 14, 1973. Its orbiting operations came to a premature end
on July 11, 1979, when Skylab plummeted through the atmosphere, sending chunks of debris
raining down over an area stretching from the Southeastern Indian Ocean across a sparsely
populated section of Western Australia.

10. Threat to Space Missions
From the initial days onwards NASA is monitoring the orbital path of their space shuttles to find and
avoid any debris along the path of shuttle. During the 1980s, these simulations used up a
considerable amount of the NORAD tracking system's capacity. The first official Space Shuttle
collision avoidance maneuver was during STS-48 in September 1991. A 7-second reaction control
system burn was performed to avoid debris from the Cosmos satellite955.
One of the first events to widely publicize the debris problem was Space Shuttle Challenger's second
flight on STS-7. A small fleck of paint impacted Challenger's front window and created a pit over
1 mm (0.04 in) wide. Endeavour suffered a similar impact on STS-59 in 1994, but this one pitted the
window for about half its depth: a cause for much greater concern. Post-flight examinations have
noted a marked increase in the number of minor debris impacts since 1998.
The damage due to smaller debris has now grown to become a significant problem in its own right.
Chipping of the windows became common by the 1990s, along with minor damage to the thermal
protection system tiles (TPS). To mitigate the impact of these events, once the Shuttle reached orbit
it was deliberately flown tail first in an attempt to intercept as much of the debris load as possible on
the engines and rear cargo bay. These were not used on orbit or during descent and thus were less
critical to operations after launch. When flown to the ISS, the Shuttle was placed where the station
provided as much protection as possible.
The sudden increase in debris load led to a re-evaluation of the debris issue and a catastrophic
impact with large debris was considered to be the primary threat to Shuttle operations on every
mission. Mission planning required a thorough discussion of debris risk, with an executive level
decision to proceed if the risk is greater than 1 in 200 of destroying the Shuttle. On a normal low-
orbit mission to the ISS the risks were estimated to be 1 in 300, but the STS-125 mission to repair
the Hubble Space Telescope at 350 mi (560 km) was initially calculated at 1 in 185 due to the 2009
satellite collision, and threatened to cancel the mission. However, a re-analysis as better debris
numbers became available reduced this to 1 in 221, and the mission was allowed to proceed.

11. Measures taken for Cleaning Space Debris
With half a million pieces of space debris cluttering Earth's orbit, according to NASA, this means
there is a growing problem of cluttering up our access road to space. Several companies and entities
have proposed ways to get rid of derelict satellites and other space junk.
Europe's e.DeOrbit Idea: The e.DeOrbit mission, first proposed publicly in early 2014 – would seek
out satellite debris in a polar orbit at an altitude between 800 and 1,000 kilometers (500 to 620
miles). The European Space Agency is considering several kinds of "capture mechanisms" to pick
up the debris, such as nets, harpoons, robotic arms and tentacles.
Image courtesy: http://www.redorbit.com/media/uploads/2013/04/Concept_for_future_deorbit_mission-617x416.png
Swiss CleanSpace One Nanosatellite: CleanSpace One, a technology demonstration spacecraft,
is expected to launch in 2018 from the back of a modified Airbus A300 jumbo jet. The Swiss Space
Systems satellite would then meet up with a decommissioned SwissCube nanosatellite to move it
out of orbit.
Image Courtesy: http://www.globalpost.com/sites/default/files/imagecache/gp3_slideshow_large/cleanspace_one_space_debris_satellite.jpg

12. Japan's Electrodynamic Tether: The Japanese Aerospace Exploration Agency proposes to use
an electrodynamic tether whose current would slow down the speed of satellites or space debris,
according to an early 2014 report from Agence France-Presse. Slowing the satellite speed would
make it gradually fall closer to Earth, where it will burn up. A satellite using part of the system was
expected to launch Feb. 28 (without capturing a satellite), with a tether test proposed for 2015.
Image Courtesy: http://www.extremetech.com/wp-content/uploads/2014/01/01-fig02.jpg
Space Debris Slingshot: To save on fuel, Texas A&M University's Sling-Sat Space
Sweeper proposes swinging capturing an object, swinging it towards Earth's atmosphere, and then
using the momentum to sail on to the next piece of space debris for removal. The researchers were
still examining design ideas as of early 2013.
Image Courtesy: http://rootnotion.co.uk/wp-content/uploads/2014/05/slingsat-space-junk-removal.jpg

13. Space Junk Solar Sail: A British proposal called CubeSail would use the drag of a solar sail to
push orbiting space debris down to lower orbits. Initially slated to fly in 2011, the proposal is still
under design and is expected to build on more recent small satellite experience from its maker
Surrey Space Centre, specifically theSTRaND-1 nanosatellite that flew in February 2013.
Image courtesy: http://media2.s-nbcnews.com/j/MSNBC/Components/Photo/_new/100428-tech-cube%20sail.grid-6x2.jpg
Huffing and Puffing: This method (called Space Debris Elimination, or SpaDE) would push
satellites into a lower orbit by using air bursts within the atmosphere. A design proposal from Daniel
Gregory of Raytheon BBN Technologies in Virginia would use a balloon or high-altitude plain to
send the bursts out, which early studies in 2012 indicated could be enough to disturb the paths of
low-Earth orbital debris.
Space Debris Net: A network of nanosatellites, connected with a piece of electrically conducting
tape that could be as long as 2 miles (3 kilometers), could knock satellites down as it passes through
Earth's magnetic field and produces voltage. The solar-powered Electrodynamic Debris

14. Eliminator (proposed by Star Technology and Research, Inc.) could get rid of all large pieces of
satellite debris in low-Earth orbit within a dozen years.
The Phoenix: The military's Defense Advanced Research Projects Agency (DARPA) has started a
program called Phoenix, which seeks to recycle still-functioning pieces of defunct satellites and
incorporate them into new space systems on the cheap. The Phoenix program aims to use a robot
mechanic-like vehicle to snag still-working antennas from the many retired and dead satellites in
geosynchronous orbit — about 22,000 miles (35,406 Km) above Earth — and attach them to smaller
"satlets," or nanosatellites, launched from Earth.
Image Courtesy: http://techcrash.net/wp-content/uploads/2012/07/161_Phoenix-artists-concept-still-shot-2.jpg
Earth-Based Lasers: A ground-based laser could de-orbit space debris by robbing it of a bit of the
momentum it needs to continue orbiting the Earth. Light exerts pressure, so to de-orbit an object
such as the discarded ASTRO-F satellite lens acp-31 inches wide and 5 Kg in mass, a laser beam
of about 5 to 10 Kilowatts would be shined upon it for about 2 hours.

15. ISRO – Space Debris
The Indian Space Research Organization (ISRO) recognizes the importance of the current space
debris scenario, and the impact it has on the effective utilization of space technology for the
improvement in the quality of life on the Earth. ISRO is committed to effective management of the
threats due to space debris. Towards this commitment ISRO works on different aspects of space
debris, including the debris mitigation measures.
ISRO successfully designed and developed a propellant venting system for implementation in the
existing upper stage of India's Polar Satellite Launch Vehicle (PSLV), which uses Earth-storable
liquid propellants. GSLV also employs passivation of the Cryogenic Upper Stage at the end of its
useful mission. ISRO developed its debris environmental models and software to predict the close
approach of any of the debris to the functional satellites. ISRO recognizes the role of international
cooperation in the debris mitigation measures and actively contributes to the efforts of the Inter-
Agency Space Debris Coordination Committee (IADC) and United Nations Committee on the
Peaceful Uses of Outer Space (UNCOPUOS).
Recently ISRO organized National Conference on Space Debris Management & Mitigation
Techniques. Some of the conference topics include but not limited to:
 Debris environment modelling
 On-orbit & re-entry risk assessments
 Orbit prediction & determination
 Hyper velocity impacts & protection
 Radar, optical & in-situ measurements
 Space surveillance & catalogues
 Long term sustainability of Space
 Debris mitigation & remediation
 Active debris removal
 Long term sustainability of outer space
 Standardization, policies & legal issues
 Space security
 Space traffic management systems

16. Conclusion
Space Debris has become the topic of big concern now-a-days. Space debris creation can’t be
stopped completely, but it can be reduced by adopting some measures. Many methods of space
debris cleaning have been proposed earlier by many scientists, but some have limitations. After
some modification they can be beneficial in the process of space debris mitigation.
Some new methods of space debris cleaning have been proposed like, use of decaying material,
and nano technology for retrieval of this space junk. Moreover, we can also use the space junk for
energy generation or in making recycled rockets and satellites.
Recent studies shows that the number of objects in the space is increasing exponentially, if this
continues, no more space missions can be possible and we may be stuck here on Earth which would
be the worst case for our future.
The Earth is already polluted, and now we must see that at least our space is kept least polluted for
our safe exploration to the outer space and also for the safety of aliens from other planets if they
happen to exist.

17. Bibliography
 http://www.space.com/23039-space-junk-explained-orbital-debris-infographic.html
 http://news.discovery.com/space/space-junk-recycle-problem-110904.htm
 http://www.spacefuture.com/archive/space_debris_and_its_mitigation.shtml
 http://en.wikipedia.org/wiki/Space_debris#Dealing_with_debris
 http://www.extremetech.com/extreme/175230-japan-is-preparing-to-launch-a-giant-
magnetic-net-that-will-trawl-space-for-junk
 http://www.space.com/24895-space-junk-wild-clean-up-concepts.html
 http://www.space.com/11157-nasa-lasers-shooting-space-junk.html
 http://asi-sdmmt2014.isro.gov.in/?q=conference-topics
 http://orbitaldebris.jsc.nasa.gov/reentry/recovered.html
 http://www.spacesafetymagazine.com/space-debris/kessler-syndrome/
 http://science.howstuffworks.com/space-junk2.htm
 http://www.research.utoronto.ca/what-is-space-junk-and-why-is-it-so-dangerous/
 http://www.popularmechanics.com/science/space/news/5-high-tech-space-junk-
solutions#slide-1
 http://www.space.com/topics/space-junk-orbital-debris-news/
 http://www.space.com/13339-darpa-space-junk-recycling-phoenix-satellites.html
 http://www.bbc.com/future/story/20120518-danger-space-junk-alert
 Space Elevator Survivability Space Debris Mitigation – google books
 Google Images.
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