by staff writers for Launchspace
Bethesda MD (SPX) Jun 13, 2013
The topic of "space debris" is hot, and getting hotter! Spacefaring nations and the space community are concerned about this growing impediment to future space flight. NASA, DoD, FAA, ESA and the UN are all aware of the issues. There are international debris commissions and committees studying potential mitigation and remediation solutions.
High anxiety is running rampant among these groups. Every mitigation technique has been reviewed and many are being pursued. Most new satellites have the ability to either de-orbit or move out of the way at their end-of-mission. Upper stage providers have been asked to vent their propellant tanks of residual propellant before discarding them. Many satellites that are able to maneuver do so to avoid close-conjunction events.
The Air Force has been beefing up its satellite and debris tracking capabilities. National and international working groups continue to meet regularly to assess the growing potential collision threats and recommend actions for all spacefaring nations. The world of satellite operators may be just one major satellite collision event away from panic.
Instances of close conjunction events in those few highly congested orbital bands have increased dramatically in the past several years. For example, the frequency of potential encounter events between active satellites and large debris objects near active satellite constellations has reached a very high level.
Odds are that there will be another satellite/debris encounter sometime in the not-too-distant future. This could be tomorrow, or next month, or next year, or next decade. We don't know when, but it will surely happen. When it does, several bad things may happen to an unfortunate satellite operator.
A spacecraft may have to be replaced. The frequency of close encounters in orbits near that of encounter would suddenly increase to levels that will cause increased anxiety to several operators. Satellite insurance providers would be forced to raise premiums on in-orbit performance to record high levels.
Future launch plans for almost all low orbiting satellites may have to be reviewed and changed. Space-based services to the world society may diminish over time. The worldwide impact on national economies and the quality of life are not even calculable.
Although space debris proliferation presents a long-term challenge that will require a long-term solution, the immediate problem is quite bounded. Recent studies of debris distribution reveal the near-term troubled zone to be a spherical shell between the altitudes of 700 km and 900 km. This is where a great many operational satellites and large debris objects co-exist.
One suggested near-term partial solution by NASA is to remove a limited number of large debris objects that reside in the high density zone. This approach could retard the growth of collision risk levels and lead to values that are consistent with statistical times-between-debris-collisions that are much higher than expected satellite mission lifetimes.
Such an operation would have to be continued on a long-term basis, requiring the removal of some large objects each year. Such debris removal missions are possible, but complex and expensive.
In an ideal world, all affected nations and parties would collaborate and contribute to the creation of a massive new space effort. There are literally well over 1,000 large debris objects that pose immediate threats. Of these, a few of the most threatening objects could be removed annually. There are a number of ways to do this. Let's take one approach as an example. Start by developing a specially designed "Debris Collection Spacecraft."
Each DCS could be capable of maneuvering and rendezvousing with one or more objects, but one at a time. Each object may be stored for later de-orbit, or fitted with an autonomous de-orbit unit that slows the object's orbital speed. If each DCS is able to deal with four objects, assuming only eight objects need to be removed annually, the job will require two DCS missions each year.
This whole removal operation must be transparent to commercial, civil and security satellite operators. In order to be effective, the removal program needs to start almost immediately to insure objects are removed in time to avoid potential future collisions.
The development costs of DCS spacecraft may be in the several hundred-million-dollar neighborhood, with an annual operating budget at about $500 million to $1 billion. This seems like an expensive program, but the cost of doing nothing may be much greater.
For all those who are concerned and interested in the space debris crisis, get smart on the space debris issues and possible solutions. Launchspace can help. Contact us to learn more.
Space Technology News - Applications and Research
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