FIGURE 7.1 LDEF was returned to Earth using the space shuttle. The space shuttle also returned the Satellites Palapa and Weststar; however, these satellites were “cooperative” in that they were stable and designed to be handled by the space shuttle. Returning a possibly spinning satellite that was not designed to be handled is a more difficult problem, even more so without the capabilities of a crewed space shuttle. SOURCE: Courtesy of NASA-JSC.
Objects have been removed from orbit, such as the LDEF satellite shown in Figure 7.1, but these were planned and designed for easy removal using the space shuttle. Various concepts for removing debris are discussed in DARPA’s recently released “Catcher’s Mitt” Final Report,7 and include the use of nets and harpoons to capture large objects, and tethers, drag augmentation devices, and solar sails to remove the objects. Other potential removal solutions that have flown in orbit or been tested on the ground are electrodynamic and momentum tethers; drag augmentation devices; solar sails; ground-based and space-based lasers; and soft-catch collection media. Many show some promise; however, necessary safeguards must also be addressed and tested to ensure that any operation system does not contribute to the production of orbital debris through unintentional consequences.
Finding: Enhanced mitigation standards or removal of orbital debris are likely to be necessary to limit the growth in the orbital debris population. Although NASA’s orbital debris programs have identified the need for orbital debris removal, the necessary economic, technology, testing, political, or legal considerations have not been fully examined, nor has analysis been done to determine when such technology will be required.
7 W. Pulliam, Catcher’s Mitt Final Report, Tactical Technology Office, Defense Advanced Research Projects Agency, Arlington, Va.