Transcript Space Debris - University of Delaware

Space
Debris
By: Ashley Barrera
Astronomy 133
Spring 2009
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?
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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.
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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 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.
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.
 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.
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.
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.
Gabbard Diagrams
We can use scatter plots to study space
debris clouds from satellite breakups.
Perigee and apogee altitudes of the individual
debris fragments after a collision are plotted
with respect to the orbital period of each
fragment.
By plotting these graphs, we can estimate an
object’s direction and point of impact.
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Examples of
Debris
Collisions in Space
This photo
shows the
antenna
dish of the
Hubble
Space
Telescope
which was
completely
penetrated
by space
debris.
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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.
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Possible
Solutions
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 deorbit 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.
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.
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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.
CounterClaims
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 threequarters 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."
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.
What Do YOU Think?
Is space debris just another over hyped
scientific issue, or could this really become a
larger problem in the future?
Should we leave it all up there, or take the
time and money to bring it down?
If you feel strongly, you can contact:
Public Communications Office
NASA Headquarters
Suite 5K39
Washington, DC 20546-0001
Or your local Congressman/Congresswoman
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