tugas sas - space debris

8/6/2019 Tugas SAS - Space Debris

http://slidepdf.com/reader/full/tugas-sas-space-debris 1/22

S P A C E D E B R I S

ByWilson Fonda 16510048

Hadi Setiadi 16510176

Timotius Kevin L. 16510236

N. Adriel L. 16510356Adam Akhmad Akbar 16510388



Contents

1. Space Debris

2. Characterization

3. Sources of Debris4. Operational Aspect

5. Dealing with Debris



Space Debris

Space debris (also known as orbital debris, space junk, and space waste) is the collection of objects inorbit around Earth that were created by humans but nolonger serve any useful purpose. These objects consist

of everything from spent rocket stages and defunctsatellites to explosion and collision fragments. Thedebris includes slag and dust from solid rocket motors,surface degradation products such as paint flakes,coolant released by RORSAT nuclear powered satellites,

clusters of small needles, and objects released due tothe impact of micrometeoroids or fairly small debrisonto spacecraft. As the orbits of these objects oftenoverlap the trajectories of spacecraft, debris is apotential collision risk.



Characterization

1. Large Vs. Small

2. Debris in Low Earth orbit

3. Debris at higher altitudes



Large Vs. Small

Any discussion of space debris generally categorizes

large and small debris. "Large" is defined not by its size so

much as the current ability to detect objects of some lower

size limit. Generally, large is taken to be 10 centimetres (3.9in) across or larger, with typical masses on the order of 1

kilogram (2.2 lb). Logically it would follow that small debris

would be anything smaller than that, but in fact the cutoff

is normally 1 centimetre (0.39 in) or smaller. Debris

between these two limits would normally be considered"large" as well, but goes unmeasured due to our inability to

track them.



Debris in Low Earth Orbit

Every satellite, space probe and manned mission has

the potential to create space debris. Any impact between

two objects of sizeable mass spalls off shrapnel debris from

the force of collision. Each piece of shrapnel has thepotential to cause further damage, creating even more

space debris. With a large enough collision (such as one

between a space station and a defunct satellite), the

amount of cascading debris could be enough to render Low

Earth Orbit (LEO) essentially unusable.



Debris at Higher Altitudes

At higher altitudes, where atmospheric drag is less

significant, orbital decay takes much longer. Slight

atmospheric drag, lunar perturbations, and solar radiation

pressure can gradually bring debris down to lower altitudeswhere it decays, but at very high altitudes this can take

millennia. Thus while these orbits are generally less used

than LEO, and the problem onset is slower as a result, the

numbers progress toward the critical threshold much more

quickly.



Sources of Debris

1. Dead Spacecraft

2. Lost Equipment

3. Boosters4. Debris from and as A Weapon



Dead Spacecraft

In 1958 the United States launched Vanguard I intoa medium Earth orbit (MEO). It became one of thelongest surviving pieces of space junk and as of October 2009 remains the oldest piece of junk still in

orbit.In a catalog listing known launches up to July 2009,

the Union of Concerned Scientists listed 902operational satellites. This is out of a known populationof 19,000 large objects and about 30,000 objects ever

launched. Thus, operational satellites represent a smallminority of the population of man-made objects inspace. The rest are, by definition, debris



Lost Equipment

Debris is also commonly caused during space-walks.

According to Edward Tufte's book Envisioning Information,space debris objects have included a glove lost by astronautEd White on the first American space-walk (EVA); a camera

Michael Collins lost near the spacecraft Gemini 10; garbagebags jettisoned by the Soviet cosmonauts throughout theMir space station's 15-year life; a wrench and a toothbrush.Sunita Williams of STS-116 also lost a camera during EVA. Inan EVA to reinforce a torn solar panel during STS-120, a pairof pliers was lost and during STS-126, HeidemarieStefanyshyn-Piper lost a briefcase-sized tool bag in one of the mission's EVAs.



Boosters

Lower stages, like the solid rocket boosters of theSpace Shuttle, or the Saturn IB stage of the Apollo programera, do not reach orbital velocities and do not add to themass load in orbit. Upper stages, like the Inertial UpperStage, start and end their productive lives in orbit. Boostersremain a serious debris problem and one of the majorknown impact events was due to an Ariane booster.

During the initial attempts to characterize the spacedebris problem, it became evident that a good proportionof all debris was due to the breaking up of rocket boosters.

Although NASA quickly made efforts to improve thesurvivability of their boosters, other countries did notfollow suit for some time. On 11 March 2000, a ChineseLong March 4's CBERS-1/SACI-1 upper stage exploded inorbit and created a debris cloud.



Operational Aspect

1. Threat to Unmanned Spacecraft

2. Threat to Manned Spacecraft

3. Hazard on Earth



Threat to Unmanned Spacecraft

Spacecraft in a debris field are subject to constantwear as a result of impacts with small debris. Critical areasof a spacecraft are normally protected by Whipple shields,eliminating most damage. However, low-mass impacts have

a direct impact on the lifetime of a space mission, if thespacecraft is powered by solar panels. These panels aredifficult to protect because their front face has to bedirectly exposed to the sun. As a result, they are oftenpunctured by debris. When hit, panels tend not to producenew debris as much as a cloud of gas-sized particles that

does not present as much of a risk to other spacecraft. Thisgas is generally a plasma when created and consequentlypresents an electrical risk to the panels themselves.Oly mpus was rendered effectively dead after such acollision, although this was from a Perseid meteor, not

spacecraft debris.



Threat to Manned Spacecraft

From the earliest days of the Space Shuttle missions,

NASA has turned to NORAD's database to constantly

monitor the orbital path in front of the Shuttle to find and

avoid any known debris. At one point these simulationsused 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 satellite 955. Similarmaneuvers followed on missions 53, 72 and 82.



Hazard on Earth

Although most debris will burn up in the atmosphere,

larger objects can reach the ground intact and present a

risk.

The original re-entry plan for Skylab called for thestation to remain in space for 8 to 10 years after its final

mission in February 1974. Unexpectedly high solar activity

pushed the space station's orbit closer to Earth than

planned. On 11 July 1979, Skylab re-entered the Earth's

atmosphere and disintegrated, raining debris harmlessly

along a path extending over the southern Indian Ocean and

sparsely populated areas of Western Australia.



Dealing with Debris

1. Growth Mitigation

2. Self Removal

3. External Removal4. Studies/Legal and Contractual Efforts



Growth Mitigation

In order to mitigate the generation of additional spacedebris, a number of measures have been proposed. Thepassivation of spent upper stages by the release of residualfuels is aimed at reducing the risk of on-orbit explosions thatcould generate thousands of additional debris objects. The

previously mentioned change to the Delta boosters in theearly days of the debris characterization essentially eliminatedtheir future contribution.

One alternative that has been envisioned to ensurelaunch vehicle operators absorb the cost of debris mitigationis to implement a "one-up/one-down" launch license regimeto Earth orbits. In this conception, launch operators wouldneed to build the capability into their launch vehicleroboticcapture, navigation, mission duration extension, andsubstantial additional fuelto be able to rendezvous with,capture and deorbit an existing derelict satellite from

approximately the same orbital plane.



External Removal

The vast majority of space debris, especially smallerdebris, cannot be removed under its own power. A varietyof proposals have been made to directly remove suchmaterial from orbit. These range from large spacecraft

capture and hazard mitigation to "laser brooms" forremoving small pieces of debris.

One external debris removal technology is currentlywithin five years of implementation. The commercially-developed MDA Space Infrastructure Servicing vehicle is arefueling depot and service spacecraft for communicationsatellites in geosynchronous orbit-slated to be the first in-space propellant depot in the history of spaceflight. Launchis planned for 2015. The SIS vehicle includes the vehiclecapability to "push dead satellites into graveyard orbits."



Studies/Legal and Contractual Efforts

The United States Defense Advanced Research Projects

Agency (DARPA) conducted a 2009 study to "better

understand the issues and challenges involved with

removing man-made debris from Earth orbit."



Sourcehttp://en.wikipedia.org/wiki/Space_debris

tugas sas - space debris

Documents