PPT on Space Debris

1. Debris

2. Space debris (also known as space junk, space pollution, space waste, space trash,
or space garbage) are defunct human-made objects in space—principally in Earth orbit—
which no longer serve a useful function.
These include derelict spacecraft—nonfunctional spacecraft and abandoned launch
vehicle stages—mission-related debris, and particularly numerous in Earth orbit,
fragmentation debris from the breakup of derelict rocket bodies and spacecraft.
Smaller pieces of space debris include fragments of vehicles that exploded or collided and
bits of insulation and paint that have come off of space vehicles.
Other examples of space debris include fragments from their disintegration, erosion,
and collisions, or even paint flecks, solidified liquids expelled from spacecraft, and
unburned particles from solid rocket motors. Space debris represents a risk to spacecraft.
Much of the debris is in low Earth orbit, within 2,000 km of Earth’s surface, though some
debris can be found in geostationary orbit 35,786 km above the Equator. Objects below
600 km orbit several years before reentering Earth’s atmosphere. Objects above 1,000 km
will orbit for centuries.

3. Space debris began to accumulate in
Earth’s orbit immediately with the
first launch of an artificial satellite
Sputnik 1 into orbit in October 1957.
But even before that, besides natural
ejecta from Earth, humans might
have produced ejecta that became
space debris, as in the August 1957
Pascal B test.
After the launch of Sputnik, the North
American Aerospace Defense
Command (NORAD) began
compiling a database (the Space
Object Catalog) of all known rocket
launches and objects reaching orbit:
satellites, protective shields, and
upper-stages of launch vehicles.

4. 1. Low Earth Orbit (LEO)
2. Medium Earth Orbit (MEO)
3. Geostationary Orbit (GEO)

5. In the orbits nearest to Earth—less
than 2,000 km (1,200 mi) orbital
altitude, referred to as low-Earth orbit
(LEO)—there have traditionally been
few "universal orbits" that keep a
number of spacecraft in particular rings
(in contrast to GEO, a single orbit that
is widely used by over 500 satellites).
This is beginning to change in 2019, and several companies have begun
to deploy the early phases of satellite internet constellations, which will
have many universal orbits in LEO with 30 to 50 satellites per orbital
plane and altitude. This will make a cascading even a lot more likely.
Satellite hit by a space debris, animation by ESA

6. According to the ESA, space debris include:
Payload: these are mainly satellites. This includes
fragments produced by wear and tear and collisions.
Rockets: remains of stages used to propel missions
in orbit. This also includes fragments produced by
wear and tear and collisions.
Mission-related objects: for example, dropped tools,
screws, cables, cameras, etc.

7. Space waste is classified by size as follows:
Below 1 cm: it is estimated that there are more than 128
million of these fragments and most of them are
undetectable.
Between 1 and 10 cm: it is calculated that there are
around 900,000 in orbit, which range from the size of a
marble to a tennis ball.
More than 10 cm: these objects include everything from
tools lost during missions to defunct satellites.

8. Rocket stages: Some rocket stages are discarded in low orbits and fall to
Earth shortly after takeoff. However, the higher ones are left drifting in
space and sometimes explode because they contain the remains of fuel.
These explosions create thousands of fragments.
Weapons: In characterizing the problem of space debris, it was learned that
much debris was due to rocket upper stages (e.g. the Inertial Upper Stage)
which end up in orbit, and break up due to the decomposition
of unvented unburned fuel.
Defunct satellites: Satellites have a limited useful life and, when their
batteries are spent or they break down, they are left drifting about in space.
At the beginning of the space race, it was assumed that sooner or later
these abandoned objects would fall to earth and would burn up on re-entry.
However, and particularly at higher orbits, this may never happen.

9. Barriers: With the rapid development of the computer and digitalization
industries, more countries and companies have engaged in space activities
since the turn of the 20th century
Missing equipment: Astronauts sometimes drop tools or other objects during
space walks. In 2008, for example, astronaut Heidemarie Stefanyshyn-Piper
dropped a box of tools. This disintegrated when it entered the Earth's
atmosphere almost a year later, after orbiting the Earth more than 4,000
times.
Weapons: Both the United States and the Soviet Union began to conduct
tests with anti-satellite weapons in the sixties and seventies. In 1985, for
example, the United States destroyed a one-ton satellite (Solwind) with one
of these weapons. Similar missions of this type were carried out in later
years by other countries including China and India.

10. As of January 2019, more than
128 million pieces of debris
smaller than 1 cm, about
900,000 pieces of debris 1–
10 cm, and around 34,000 pieces
larger than 10 cm were estimated
to be in orbit around the Earth.
As of January 2021, the US
Space Surveillance
Network reported 21,901
artificial objects in orbit above
the Earth. However, these are
just objects large enough to be
tracked.
The spike in 2007 was caused by China testing it’s new
anti-satellite technology.

11. In 2007, the ISO began preparing an international standard for space-debris
mitigation.
By 2010, ISO had published "a comprehensive set of space system engineering
standards aimed at mitigating space debris. [with primary requirements] defined in
the top-level standard, ISO 24113." By 2017, the standards were nearly complete.
However, these standards are not binding on any party by ISO or any international
jurisdiction. They are simply available for use in any of a variety of voluntary
ways.
They "can be adopted voluntarily by a spacecraft manufacturer or operator, or
brought into effect through a commercial contract between a customer and
supplier, or used as the basis for establishing a set of national regulations on space
debris mitigation."

12. A small piece of space debris
traveling at 17,000 miles per hour
carries a lot of energy. This photo
depicts damage to the Hubble
telescope caused by debris. Photo
Credit: NASA
More than 27,000 pieces of orbital debris, or “space
junk,” are tracked by the Department of Defense’s
global Space Surveillance Network (SSN) sensors.
Much more debris -- too small to be tracked, but large
enough to threaten human spaceflight and robotic
missions -- exists in the near-Earth space
environment. Since both the debris and spacecraft are
traveling at extremely high speeds (approximately
15,700 mph in low Earth orbit), an impact of even a
tiny piece of orbital debris with a spacecraft could
create big problems.
The rising population of space debris increases the
potential danger to all space vehicles, including to the
International Space Station and other spacecraft with
humans aboard, such as SpaceX’s Crew Dragon.

13. According to the ESA, since 1961 there have been more than 560 fragmentation
incidents, most of them caused by fuel explosions in rocket stages. As for direct
collisions, there have only been seven, the most serious of which destroyed an
inactive Russian satellite called Kosmos 2251 and the operational satellite Iridium 33.
However, it is the small fragments that pose the greatest danger. Micrometeorites like
paint flakes and solidified droplets of antifreeze can damage solar panels on active
satellites. Other dangerous debris includes vestiges of solid fuel which float about in
space and are highly flammable. They can cause damage and disperse pollutants into
the atmosphere if they explode.
Some Russian satellites contain nuclear batteries with radioactive material that could
cause dangerous contamination if they returned to Earth. In any case, the heat of
reentry destroys the majority of this space debris before it reaches the Earth. On rare
occasions, larger fragments have reached the surface and caused considerable
damage.

14. Space debris includes a glove lost by
astronaut Ed White on the first American space-
walk (EVA), a camera lost by Michael
Collins near Gemini 10, a thermal blanket lost
during STS-88, garbage bags jettisoned by
Soviet cosmonauts during Mir's 15-year life, a
wrench, and a toothbrush. Sunita
Williams of STS-116 lost a camera during an
EVA. During an STS-120 EVA to reinforce a torn
solar panel, a pair of pliers was lost, and in
an STS-126 EVA, Heidemarie Stefanyshyn-
Piper lost a briefcase-sized tool bag.
A drifting thermal
blanket photographed in
1998 during STS-88.

15. It is theorized that a sufficiently large collision of spacecraft could potentially lead to a cascade
effect, or even make some particular low Earth orbits effectively unusable for long-term use by
orbiting satellites, a phenomenon known as the Kessler syndrome.
The Envisat satellite is a large, inactive satellite with a mass of 8,211 kg that orbits at 785 km,
an altitude where the debris environment is the greatest—two cataloged objects can be expected
to pass within about 200 m of Envisat every year—and likely to increase.
SpaceX's Starlink program raises concern among many experts about significantly worsening
the possibility of Kessler Syndrome due to a large number of satellites the program aims to
place in LEO, as the program's goal will more than double the satellites currently in LEO. orbits
The theoretical effect is projected to be a theoretical runaway chain reaction of collisions that
could occur, exponentially increasing the number and density of space debris in low-Earth orbit,
and has been hypothesized to ensue beyond some critical density.
Crewed space missions are mostly at 400 km altitude and below, where air drag helps clear
zones of fragments.

16. At the dawn of the space age in 1957, the North American Aerospace Defense Command
(NORAD) started a database with information about all this waste. The first piece of space junk
was the Sputnik satellite, which the Soviet Union launched that same year. These days, the
European Space Agency (ESA), says there are around 900,000 objects measuring between 1 and
10 cm in orbit and around 34,000 larger than 10 cm. Many are visible on this interactive map
External link, opens in new window.
The United Nations Office for Outer Space Affairs (UNOOSA) has been drawing attention to
the dangers of space waste External link, opens in new window. and the need for prevention for
many years, to the extent that back in 2007 the UN General Assembly approved a set of
guidelines to mitigate the threat. For its part, the ESA also has an information programme
External link, opens in new window. on the risks of space debris.
Because of the high speeds at which objects orbit Earth (up to 8 km per second), a collision with
even a small piece of space debris can damage a spacecraft. For example, space
shuttle windows often had to be replaced because of damage from collisions with debris smaller
than 1 mm (When in orbit, the space shuttle flew tail-forward to protect the forward crew
compartment.)

17.  The United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) is
a United Nations committee whose main task is to review and foster international
cooperation in the peaceful uses of outer space, as well as to consider legal issues
arising from the exploration of outer space.
 By 2006, the Indian Space Research Organization (ISRO) had developed a number
of technical means of debris mitigation (upper stage passivation, propellant
reserves for movement to graveyard orbits, etc.) for ISRO launch vehicles and
satellites, and was actively contributing to inter-agency debris coordination and the
efforts of the UN COPUOS committee.
 On 27 March 2019, Indian Prime Minister Narendra Modi announced that India
shot down one of its own LEO satellites with a ground-based missile. He stated that
the operation, part of Mission Shakti, would defend the country's interests in space.

18.  On March 27, 2019, India announced it also successfully completed an anti-satellite
missile test, creating a new cloud of at least 400 pieces of debris, which increased
the risk of impacts to the ISS by an estimated 44 percent over a 10-day period.
 There are a few positives, however, for that particular cloud of space junk. Unlike
China's high-altitude test in 2007, India's missile is thought to have targeted a low-
altitude satellite, Microsat-R, which means most of this debris is expected to re-
enter Earth's atmosphere over time. Even so, in a town hall following the event,
NASAAdministrator Jim Bridenstine called the debris cloud's creation
“unacceptable” and added that "when one country does it, then other countries feel
like they have to do it as well.”
 The ASAT test utilized a modified anti-ballistic missile interceptor code-
named Prithvi Defence Vehicle Mark-II which was developed under Project XSV-1.
The test made India the fourth country after the United States, Russia, and China to
have tested an ASAT weapon.

19.  Several countries including the USA, China and India have used missiles to
practice blowing up their own satellites. This creates thousands of new pieces of
dangerous debris.
 The test sparked concerns regarding the creation of space debris. The Indian
government tried to address these concerns by saying that the debris generated from the
test would not last for a long duration.
 The United States has conducted over 30 anti-satellite weapons tests the Soviet
Union/Russia has performed at least 27, China has performed 10 and India has
performed at least one. The most recent ASATs were the Chinese interception of FY-1C,
Russian trials of its PL-19 Nudol, the American interception of USA-193, and
India's interception of an unstated live satellite.
 India's successful demonstration of the ASAT capability is said to signify its ability to
intercept an intercontinental ballistic missile (ICBM). The ASAT weapon is meant to act
as a deterrent.
 On 27 March 2019, India tested an anti-satellite weapon (ASAT) during an operation
code-named Mission Shakti. The target of the test was a satellite present in a low Earth
orbit, which was hit by a kinetic kill vehicle.

20. To remove space debris, particularly the large and more dangerous objects, we
have to get close to it and maintain the same speed as each object. We
then must somehow attach to it, and move it into a lower orbit or reenter it
directly into the atmosphere, where it will burn up upon reentry. If the object is
a rocket stage with propellant still on board, there is an explosion risk, which is
why astronauts never perform this task.
There is also the issue of property rights; you can’t grab a satellite or rocket
that belongs to another country without their permission.
There is no easy way to control the small-but-dangerous objects that are not
well tracked or not tracked at all. They have more kinetic energy than bullets,
and they are moving ten times faster. It is hard to catch a bullet, especially if
you don’t want to create more junk while doing it.

21. NASA has a set of long-standing guidelines that are used to assess whether the threat of such a close pass is
sufficient to warrant evasive action or other precautions to ensure the safety of the International Space Station
and its crew.
These guidelines essentially draw an imaginary box, known as the “pizza box" because of its flat, rectangular
shape, around the space vehicle. This box is about 2.5 miles deep by 30 miles across by 30 miles long (4 x 50 x
50 kilometers), with the International Space Station in the center. When predictions indicate that any tracked
object will pass close enough for concern and the quality of the tracking data is deemed sufficiently accurate,
Mission Control centers in Houston and Moscow work together to develop a prudent course of action.
Sometimes these encounters are known well in advance and there is time to move the International Space
Station slightly, known as a “debris avoidance maneuver” to keep the object outside of the box. Other times,
the tracking data isn’t precise enough to warrant such a maneuver or the close pass isn’t identified in time to
make the maneuver. In those cases, the control centers may agree that the best course of action is to move the
crew into the Russian Soyuz or U.S. commercial crew spacecraft that are used to transport humans to and from
the station. This allows enough time to isolate those spaceships from the station by closing hatches in the event
of a damaging collision. The crew would be able to leave the station if the collision caused a loss of pressure in
the life-supporting module or damaged critical components. The spacecraft act as lifeboats for crew members
in the event of an emergency.
Mission Control also has the option of taking additional precautions, such as having the crew close hatches
between some of the station’s modules, if the likelihood of a collision is great enough.

22. The main challenge is not to produce more space waste, particularly since swarms of small
satellites are now circulating at low orbits to give high-speed internet access all over the
planet. When it comes to the debris already in orbit, many satellites, as well as the
International Space Station, are equipped with Whipple Shields, an outer shell that protects the
walls of the object from a possible collision. Here are some of the other strategies used to
avoid this problem:
Orbit changes: many modern satellites are launched into elliptical orbits with perigees within
the Earth's atmosphere, which causes them to break up eventually.
Self-destruction: consists of programming the satellite to leave its orbit at the end of its useful
life and be eliminated when it comes into contact with the atmosphere.
Passivisation: is the removal of any internal energy contained in the vehicle at the end of its
useful life. Although the chassis remains in orbit, there is less risk of explosions. The same
applies to the rocket stages.
Reuse: these rockets return to Earth intact. These are used by Space X & new companies.
Laser: consisting of stopping the fragments by vaporising their surface with a powerful
laser, which stops them and causes them to fall.

23. Video
on
Space
Debris
in
motion

25. Thank you