Orbital Debris A Technical Assessment (1995) / Chapter Skim
Currently Skimming:
7 TECHNIQUES TO REDUCE THE FUTURE DEBRIS HAZARD
7 TECHNIQUES TO REDUCE THE FUTURE DEBRIS HAZARD
Pages 135-156
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 135... ...
There are two fundamental factors to consider when assessing methods to minimize the creation of new debris. The first is how much the method will actually reduce the debris hazard to space operations.
|
From page 136... ...
Reducing the amount of mission-related debris released in spacecraft deployment and operations (e.g., clamps, covers for lenses or sensors, de-spin devices, pyrotechnic release hardware, wraparound cables) may be one of the easier ways of decreasing the future debris hazard to space operations.
|
From page 137... ...
As discussed in Chapter 3, solid rocket firings produce a vast number of very small (<10micron) debris, but their orbital lifetimes are fairly short due to the strong effect of perturbing forces such as solar radiation pressure; less than 5% will remain in orbit after a year.
|
From page 138... ...
Since there have been only two confirmed space object breakups to date due to collisions (both intentional military tests) , the vast majority of this debris is believed to have been created In explosive breakups of spacecraft and rocket bodies.
|
From page 139... ...
Passivation of Spacecraft Debris from spacecraft explosions makes up about 12.5 percent of the cataloged space object population. Spacecraft can explode both during and after their functional lifetime for a wide variety of reasons, including propellant tank explosions, thruster malfunctions, tank failures due to the impact of small debris, battery ruptures, accidentally induced high rotation rates, other degradations of the structure, or deliberate explosions.
|
From page 140... ...
Passivation of Rocket Bodies Debris generated through the explosive breakup of liquid-fueled rocket bodies after they have completed their missions makes up 25 percent of the cataloged space object population, and probably a large fraction of the uncataloged large and medium-sized debris population. Rocket body breakups are believed to be caused most often by the residual propellant (as much as several hundred liters)
|
From page 141... ...
In principle, depletion burns can shorten the rocket body's orbital lifetime, although past burns of some rocket bodies have increased orbital lifetime. (See the discussion of orbital lifetime reduction later in this chapter.)
|
From page 142... ...
The few cataloged objects believed to be released due to surface degradation have had high ratios of cross-sectional area to mass and have experienced relatively rapid orbital decay. The vast numbers of small particles released due to surface degradation are also suspected to have high ratios of cross-sectional area to mass and thus fairly short orbital lifetimes (as discussed in Chapter 3)
|
From page 143... ...
at EOL; (2) orbital lifetime reduction (accelerating the natural decay of spacecraft and other space objects to reduce the time that they remain in orbit)
|
From page 144... ...
Both spacecraft and rocket bodies may rewire some modifications to carry out deorbiOng or ~fehme reduction maneuvers. Some spacecraft may not have attitude or orbit control systems capable of performing EOL burns; such systems are necessary to execute reorbiEng or lifetime reduction ~a~er~ Rocket bodies may need educed batteries/ ath~de control and command systems in order to remain ~nchonal long enough to perform the retarding thrust maneuver.
|
From page 145... ...
(The propellant mass fraction is the mass of the propellant divided by the total mass of the space vehicle, including propellant.) As can be seen, the mass of fuel required to deorbit a spacecraft or rocket body is greater than the amount needed to reduce its orbital lifetime.
|
From page 147... ...
Disposal Orbits Deorbiting or meaningfully accelerating the orbital decay of spacecraft or rocket bodies from most widely used high-altitude orbital re
|
From page 148... ...
A considerable number of GEO spacecraft and some spacecraft in semisynchronous orbits have already performed reorbiting maneuvers to reduce the future debris hazard in those orbits. Spacecraft in the semisynchronous Global Positioning System constellation have performed end-of-life reorbiting maneuvers to disposal orbits from approximately 220 to 810 km above or 95 to 250 km below their initial orbits.
|
From page 149... ...
Moving a space object into a disposal orbit reduces the collision hazard in the object's initial orbital region, but increases the collision hazard in its new orbital region. Objects moved to disposal orbits can still contribute to the debris hazard in their original orbit, however, since debris generated through collisions or explosions that take place in disposal orbits may intersect the original orbit.
|
From page 150... ...
The fuel required to move to a disposal orbit a certain distance above the initial orbit decreases with increasing initial orbital altitude. Figure 7-7 shows the change in velocity required to reach disposal orbits from three orbital regions.
|
From page 152... ...
Even if all new GEO spacecraft were launched to the stable plane, they would still face a collision hazard from the objects that currently exist at other inclinations at the GEO altitude, although the overall collision hazard would be lower than if current practices were continued. Since major problems exist in schemes to reorbit within the GEO altitude, the reorbiting of GEO spacecraft into disposal orbits with altitudes above of; below GEO is the only practical method of removing mass from GEO.
|
From page 153... ...
functional spacecraft can change their operational longitude without interference. The use of disposal orbits a minimum of 300 km above GEO was recently recommended by the Ad Hoc Expert Group of the International Academy of Astronautics (International Academy of Astronautics, 1992~.
|
From page 154... ...
In general, significant reductions in orbital lifetime can be achieved with much less fuel than deorbiting would require. Finding 3: Reorbiting spacecraft and rocket bodies into disposal orbits can reduce the debris hazard in their original orbit, but it is not a permanent solution since the debris remains in Earth orbit.
|
From page 155... ...
1993. Reduced debris hazard resulting from a stable inclined geosynchronous orbit.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.