Abstract:
A debris removal management system and a method of removing space debris. In one embodiment, the system includes: (1) a frame, (2) a plurality of net sections coupled to the frame and (3) a plurality of microvehicles, coupled to the plurality of net sections, configured to employ propulsion units therein to be ejected relative to the frame to deploy the plurality of net sections, the plurality of net sections cooperating to form a net configured to capture space debris.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 12/970,319, entitled “DEBRIS REMOVAL MANAGEMENT SYSTEM AND METHOD OF OPERATION THEREOF,” filed by Daniel W. Allen, et al., on Dec. 16, 2010, which is currently pending and claims the benefit of U.S. Provisional Application Ser. No. 61/287,059, filed by Allen, et al., on Dec. 16, 2009, entitled “Debris Removal Management System,” wherein both of the above applications are commonly assigned with this application and incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This application is directed, in general, to satellites and, more specifically, to satellites capable of at least intercepting space debris. 
     BACKGROUND 
     Space debris (also known as “orbital debris,” “space junk” or “space waste”) presents a serious collision risk for launch vehicles, orbital vehicles and satellites. Space debris can range in size from spent solid rocket motor cases to nuts, bolts and tiny bits of old launch vehicles to entire spent rocket stages and defunct satellites. However, the size of the debris is essentially irrelevant, since typical collision speeds are on the order of a few to tens of kilometers per second. At those speeds, even tiny debris can punch into functioning vehicles and satellites, sometimes breaching their skin, crippling their electronics and compromising their missions. 
     The problem of space debris has only become worse over the decades. While the orbits of space debris do eventually decay, and old space debris reenters the Earth&#39;s atmosphere and is destroyed, far more debris is added each year through new vehicle launches and satellite failures than is removed through reentry. 
     The conventional response to the problem of space debris has consisted of avoiding the creation of further space debris, using sacrificial layers of protection (e.g., foil) to protect sensitive equipment, altogether steering clear of known space debris and relying on orbital decay to remove space debris. Unfortunately, foil and extra fuel add weight and complexity to space structures and do not guarantee protection, especially from larger debris; much of the smaller space debris is undetectable and so cannot be avoided; and orbital decay takes an unreasonable amount of time (sometimes decades) to happen. Consequently, space debris remains a serious threat to further space exploration and exploitation. 
     SUMMARY 
     One aspect provides a DRMS. In one embodiment, the system includes: (1) a frame, (2) a plurality of net sections coupled to the frame and (3) a plurality of microvehicles, coupled to the plurality of net sections, configured to employ propulsion units therein to be ejected relative to the frame to deploy the plurality of net sections, the plurality of net sections cooperating to form a net configured to capture space debris. 
     In another embodiment, the DRMS includes: (1) a frame including a base, (2) a plurality of net sections coupled to the frame, (3) a plurality of microvehicles coupled to the plurality of net sections and having propulsion units included thereon, the plurality of microvehicles configured to employ the propulsion units to be ejected relative to the frame and deploy the plurality of net sections, the plurality of net sections cooperating to form a net configured to capture space debris and (4) an enclosure fairing hingedly coupled to the base. 
     Another aspect provides a method of removing space debris. In one embodiment, the method includes: (1) causing a plurality of microvehicles to be ejected relative to a frame of a debris removal management system employing propulsion units of the microvehicles, the plurality of microvehicles being tethered to a plurality of net sections, (2) consequently causing the plurality of net sections to be deployed, the plurality of net sections cooperating to form a net configured to capture space debris and (3) intercepting the space debris. 
    
    
     
       BRIEF DESCRIPTION 
       Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is an elevational view of a launch vehicle that may be employed to transport various embodiments of a DRMS; 
         FIG. 2  is a cutaway view of a portion of a payload fairing of  FIG. 1  containing, in particular, a launch vehicle adapter that, in turn, supports and ultimately dispenses, a stack of two DRMSs; 
         FIG. 3  is an elevational view of the launch vehicle adapter and stack of two DRMSs of  FIG. 2  showing in greater detail a dual payload adapter associated with the launch vehicle adapter; 
         FIG. 4  is an elevational view of one of the stack of two DRMSs of  FIG. 3  following a release of one of the stack of two DRMSs and showing a release of the dual payload adapter; 
         FIG. 5  is an isometric view of one embodiment of a DRMS constructed according to the principles of the invention showing the DRMS in a fully closed state; 
         FIG. 6  is an isometric view of the DRMS of  FIG. 5  showing the DRMS in a partially open state; 
         FIG. 7  is an isometric view of the DRMS of  FIG. 5  showing the DRMS in a fully open state; 
         FIG. 8  is a plan view of the DRMS of  FIG. 7  shown in the fully open state; 
         FIG. 9  is an elevational view of the DRMS of  FIG. 7  shown in the fully open state; 
         FIG. 10  is a portion of the isometric view of  FIG. 7  showing in particular microvehicles located in respective microvehicle housings and configured to employ sections of a net; 
         FIG. 11  is a portion of the isometric view of  FIG. 7  showing doors of the microvehicle housings of  FIG. 10  in an open state; 
         FIG. 12  is a portion of the isometric view of  FIG. 7  showing the microvehicles ejecting from their respective microvehicle housings to deploy corresponding net sections; 
         FIG. 13  is a further isometric view of a portion of the DRMS of  FIG. 5  showing the microvehicles ejecting from their respective microvehicle housings to deploy corresponding net sections; 
         FIG. 14  is yet a further isometric view of a portion of the DRMS of  FIG. 13  showing the microvehicles ejecting from their respective microvehicle housings to deploy corresponding net sections; 
         FIG. 15  is a plan view of one of the microvehicles of  FIGS. 13 and 14  deploying a corresponding section of the net; 
         FIG. 16  is an isometric view of the DRMS of  FIG. 5  showing the net thereof in a fully deployed state; 
         FIG. 17  is an elevational view of the DRMS of  FIG. 5  showing the net thereof in the fully deployed state; 
         FIG. 18  is a portion of the elevational view of the DRMS of  FIG. 5  showing the net thereof in the fully deployed state; 
         FIG. 19  is an isometric view of the DRMS of  FIG. 18  approaching an example of a piece of space debris, namely a spent upper stage of a launch vehicle; 
         FIG. 20  is an isometric view of the DRMS of  FIG. 18  coming into contact with the piece of space debris; and 
         FIG. 21  is a flow diagram of one embodiment of a method of operating a DRMS carried out according to the principles of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     As stated above, space debris remains a serious threat to further space exploration and exploitation. Introduced herein are various embodiments of a DRMS configured to encounter space debris. Some embodiments of the DRMS are configured further to collect and move the space debris to another location that is regarded as being safe. That location may be in a new but safer orbit, or the DRMS may reenter with such collected debris as mission objectives may determine. 
     Mission and mission objectives often depend on object size and the velocity of the debris relative to that of the DRMS (“delta velocity”). One mission involves small debris having a high delta velocity (e.g., in excess of 7 km/sec). In such mission, the objective is not to try to collect the debris, but instead to slow the debris&#39; velocity such that its orbit is degraded at an accelerated rate, and the risk of collision is reduced. Another mission involves small debris having a low delta velocity (e.g., less than 2 km/sec) and small and large debris having very low delta velocities (e.g., less than 10 m/sec). In such mission, the objective is to capture the debris and perhaps remove it to another location (including causing the DRMS to reenter with it. Yet another mission involves a single piece of very large debris (e.g., a defunct satellite or an expended launch vehicle) having a very low delta velocity. In such mission, the objective is to capture the debris and perhaps remove it. However, the objective may involve adapting the structure of the DRMS to the size and configuration of the debris, all the better to capture it reliably. 
     Various embodiments of the DRMS have various standardized launch vehicle interfaces, allowing the DRMS to be launched on different rocket launch vehicle types and sizes, as well as allowing the DRMS to be launched as an auxiliary payload (“rideshare”). Another embodiment of the DRMS may be launched solo as a primary launch payload or launched as a rideshare with other payloads on a launch of opportunity. In other embodiments, multiple DRMSs are located on a support or host satellite and configured to be deployed on demand as the host satellite is in orbit. 
       FIG. 1  is an elevational view of a launch vehicle  100  that may be employed to transport various embodiments of a DRMS. The launch vehicle  100  has a payload fairing (PLF)  110  within which various payloads may be carried into space. In the illustrated embodiment, the launch vehicle  100  carries at least one DRMS (not shown) within its PLF  110 . The specific launch vehicle  100  illustrated in  FIG. 1  is a Falcon 1e, which is commercially available from Space Exploration Technologies Corporation of Hawthorne, Calif. However, those skilled in the pertinent art should understand that any conventional or later-developed launch vehicle capable of carrying the DRMS into space may be employed in lieu of a Falcon 1e. 
       FIG. 2  is a cutaway view of a portion of the PLF  110  of  FIG. 1  containing, in particular, a launch vehicle adapter  210  that, in turn, supports and ultimately dispenses, a stack of two DRMSs  220 ,  230 .  FIG. 2  shows the DRMSs  220 ,  230  as they may be configured during launch and initial flight of the launch vehicle  100 . 
     In the embodiment of  FIG. 2 , the DRMS  220  (a “first DRMS”) and the DRMS  230  (a “second DRMS”) are stacked in a generally vertical arrangement. A dual payload adapter  240  is associated with the launch vehicle adapter  210  and configured to allow the launch vehicle adapter  210  to support the first DRMS  220  directly and without having to employ the second DRMS  230  to support the first DRMS  220 . In the illustrated embodiment, the dual payload adapter  240  is generally cylindrical and surrounds the second DRMS  230 . As will be illustrated below, the dual payload adapter  240  is configured to be used only to effect release of the first DRMS  220 . Alternative embodiments of the dual payload adapter  240  may be employed in other phases of a mission. Alternative embodiments of the launch vehicle adapter  210  are configured to support more than two DRMSs, some in stacked configurations, some in tandem configurations. 
     In the illustrated and other, alternative embodiments, a “mother ship” (not shown) is configured to support multiple DRMSs. Various embodiments of such mother ship have a larger propulsion bus, an RCS, an EPS, a data bus system and various systems needed to navigate through space. As with the launch vehicle adapter  210  described above, one embodiment of the mother ship is attached to the launch vehicle with a suitable bus-to-launch vehicle interstage adapter interface. In various embodiments, the mother ship has one or more of navigation equipment, data links, EPS, Command, Control and Telemetry (CC&amp;T) and antennas for satellite/ground communications and other equipment. In this configuration, DRMSs could remain dormant until mission requirements dictate deployment and execution of debris management. 
       FIG. 3  is an elevational view of the launch vehicle adapter and stack of two DRMSs  220 ,  230  of  FIG. 2  showing in greater detail the dual payload adapter  240  associated with the launch vehicle adapter  210 .  FIG. 3  shows the DRMSs  220 ,  230  after the PLF  110  has been ejected but before either DRMS  220 ,  230  has been released. 
       FIG. 4  is an elevational view of one of the stack of two DRMSs  220 ,  230  of  FIGS. 2 and 3  following release of the first DRMS  220  of  FIGS. 2 and 3 ) and during release of the dual payload adapter  240 . More specifically,  FIG. 4  shows only the second DRMS  230 , and the dual payload adapter  240  is being jettisoned upwardly as shown. In the illustrated embodiment, the dual payload adapter  240  clears the second DRMS  230  before the second DRMS  230  is released. In one embodiment, the dual payload adapter  240  is tethered to the launch vehicle adapter  210  of  FIGS. 2 and 3  to prevent it from becoming another piece of space debris. Those skilled in the pertinent art should understand that other ways exist to carry one or more DRMSs on a single launch vehicle and that the broad scope of the invention is not limited to the particular embodiments illustrated and described. 
       FIG. 5  is an isometric view of one embodiment of a DRMS  500  constructed according to the principles of the invention showing the DRMS  500  in a fully closed state. 
     The DRMS  500  of  FIG. 5  has a cap  510 , an upper enclosure fairing  520  and a lower enclosure fairing  530 . A first set of hinges  540  couples the upper enclosure fairing  520  to the lower enclosure fairing  530 . A second set of hinges  550  couples the lower enclosure fairing  530  to a base  560 . In the illustrated embodiment, the upper and lower enclosure fairings  520 ,  530  serve to protect internal portions of the DRMS  500  from damage during ground processing and while in space and further offer protection from ultraviolet (UV) radiation while orbiting. As will be seen in subsequent  FIGS. 6-20 , the upper and lower enclosure fairings  520 ,  530  are divided into sections, allowing them to be peeled outward much as the skin is peeled from a banana. Thus peeled, portions of the DRMS  500  that are housed inside the upper and lower enclosure fairings  520 ,  530  are exposed and allowed to function. 
     As described above, the DRMS  500  is typically deployed in conjunction with a main bus, a propulsion bus or a support/host satellite (not shown). The propulsion bus or support/host satellite may be of any suitable conventional or later-developed type and will not be further described in  FIG. 6 , et seq., because it operates largely independently of the DRMS  500 . Its general function is to transport the DRMS  500  to a desired location and perhaps thereafter to assist the DRMS  500 , along with any space debris it may have collected, to another location. 
     In one embodiment, the DRMS  500  includes a robotic arm (not shown). In one specific embodiment, the cap  510  supports the robotic arm. In alternative embodiments, other parts of the DRMS  500  support the robotic arm. The robotic arm, if included in a particular embodiment, is configured to grasp other objects, e.g., an errant satellite, a piece of debris, a launch vehicle adapter or a launch vehicle. 
     In one embodiment, the main bus is a commercial off-the-shelf (COTS) propulsion bus having its own propulsion, reaction control system (RCS), electrical power system (EPS) and data bus system. In addition to these, the main bus typically includes a mechanical and electrical interface to the DRMS  500 , allowing it to move the DRMS  500  about and communicate and coordinate with it. In the illustrated embodiment, the main bus is attached to the DRMS  500  at one end (e.g., the base  560 ). In a related embodiment, the main bus is attached to the launch vehicle with a suitable main bus-to-launch vehicle interstage adapter interface at the other end. 
       FIG. 6  is an isometric view of the DRMS  500  of  FIG. 5  showing the DRMS  500  in a partially open state. Shown are the cap  510  and the lower enclosure fairing  530 . The upper enclosure fairing is shown partially open and divided into a plurality of upper enclosure fairing sections  620  though larger embodiments may have additional sections  620  and  730 . The specific embodiment of  FIG. 6  has four such upper enclosure fairing sections  620 . The first set of hinges ( 540  of  FIG. 5 ) allow the four upper enclosure fairing sections  620  to rotate outwardly relative to the lower enclosure fairing  530  of  FIG. 5 . Now exposed, various portions of the DRMS  500  that were previously occluded become apparent. 
       FIG. 6  shows a plurality of microvehicle housings  630 . The microvehicle housings  630  are configured to house microvehicles (not shown in  FIG. 6 , but shown and described in conjunction with subsequent FIGs.) The microvehicle housings  630  are shown without doors. In one embodiment, the microvehicle housings  630  lack doors. In the illustrated embodiment, however, the microvehicle housings  630  have doors. However,  FIGS. 6-10  omit the doors for clarity&#39;s sake.  FIGS. 11-14 , described below, show one embodiment of the doors. 
       FIG. 6  also shows a corresponding plurality of net sections  640 . In one embodiment, the plurality of net sections  640  are physically separate from one another. In an alternative embodiment, the plurality of net sections  640  are regions of the same net. In the specific embodiment of  FIG. 6 , the net sections  640  are stored as a generally cylindrical roll. In alternative embodiments, the net sections  640  are stored as multiple rolls. In further embodiments, the net sections  640  are stored as folded stacks. A support member  650  extends upwardly through a center of the net sections  640  as shown to support the plurality of microvehicle housings  630  and the cap  510 . The support member  650 , together with the base  560 , form a frame of the DRMS  500 . 
       FIG. 7  is an isometric view of the DRMS  500  of  FIG. 5  showing the DRMS in a fully open state. Both the upper and lower enclosure fairings of  FIG. 5  are shown in their fully open state. As with the upper enclosure fairing of  FIG. 6 , the lower enclosure fairing of  FIG. 7  is shown as being divided into a plurality of lower enclosure fairing sections  730 . The specific embodiment of  FIG. 7  has four such lower enclosure fairing sections  730 . Just as the first set of hinges  540  of  FIG. 5  allowed the upper enclosure fairing sections  620  to rotate outwardly relative to the lower enclosure fairing  530  of  FIG. 5 , the second set of hinges  550  of  FIG. 5  allow the lower enclosure fairing sections  730  to rotate outwardly relative to the base  560 .  FIG. 7  shows a corresponding number of actuating arms  740  that urge the lower enclosure fairing sections  730  outwardly. Although  FIG. 7  does not show them, a corresponding number of similar actuating arms are provided and configured to urge the upper enclosure fairing sections  620  to rotate outwardly. Alternative embodiments employ actuator motors in lieu of, or in addition to, the actuating arms  740  or the actuating arms for the upper enclosure fairing sections  620 . 
     In the illustrated embodiment, the net sections  640  are rolled or folded to allow large sections of net to be stored and deployed easily. In various embodiments, the net sections  640  are made of a material that is selectable in terms of type to meet a specific mission requirement. In one embodiment, the net sections  640  are made of rip-stop material (e.g., Nylon®, commercially available from the E.I. du Pont de Nemours and Company of Wilmington, Del.) to provide resistance against ripping that may otherwise occur when debris penetrates the net. In another embodiment, the net sections  640  are made of a puncture-resilient material (e.g., Kevlar®, commercially available from the E.I. du Pont de Nemours and Company of Wilmington, Del.). In yet another embodiment, the net sections  640  are made of a non electromagnetic-radiation penetrating material or any combination of materials. 
     In various embodiments, the net sections  640  are made of a material that is selectable in terms of size and shape to meet a specific mission requirement. In various embodiments, the net sections  640  range in size from large (e.g., hundreds of square meters) to small (e.g., only tens of meters) as mission requirements dictate. In the illustrated embodiment, the net sections  640  are generally triangular, with a focal point at the support member  650  with the wide part of the material  640  on the outer edge of the deployed material, though the broad scope of the invention is not limited to a particular shape or number of shapes. 
     In various embodiments to be illustrated and described herein, the net sections are attached to the DRMS  500  at inner edges thereof (e.g., to the support member  650 ) and to at least one microvehicle at outer edges thereof. In the embodiment of  FIG. 6 , the net sections are attached to the DRMS  500  at inner edges thereof and four microvehicles (one microvehicle per section) at outer edges thereof. 
       FIG. 8  is a plan view of the DRMS  500  of  FIG. 7  shown in the fully open state.  FIG. 8  is presented primarily for the purpose of illustrating how the upper and lower enclosure fairing sections  620 ,  730 , the net sections  640  and the plurality of microvehicle housings  630  may be radially arranged with respect to one another when the DRMS  500  is in its fully open state. The configuration is such that a corresponding plurality of microvehicles (not shown in  FIG. 8 ) can be ejected radially outwardly from the plurality of microvehicle housings (unreferenced in  FIG. 8 ) and how the plurality of microvehicles can deploy the net sections  630  that lie “below” them. 
       FIG. 9  is an elevational view of the DRMS  500  of  FIG. 7  shown in the fully open state.  FIG. 9  is presented primarily for the purpose of illustrating one possible relative configuration among the upper and lower enclosure fairing sections  620 ,  730 , the base  560 , the net sections  640  and the plurality of microvehicle housings  630 . The configuration is such that the plurality of microvehicle housings  630  can deploy the net sections  630  without interference from the upper and lower enclosure fairing sections  620 ,  730 . 
       FIG. 10  is a portion of the isometric view of  FIG. 7  showing in particular a plurality of microvehicles  1010  located in their respective microvehicle housings  630  and configured to employ sections of a net (not shown in  FIG. 10 ). It should be noted that the net sections  640  shown in  FIG. 7  are omitted from  FIG. 10 . 
     In the illustrated embodiment, each microvehicle includes propulsion, RCS, EPS and data bus systems  1510 . The microvehicles  1010  are configured to respond to a command from the DRMS  500  to eject and travel (e.g., linearly) to a location distal from the DRMS  500 . In doing so, the microvehicles  1010  drag corresponding net sections behind them, deploying them. The microvehicles  1010  may later respond to one or more commands from the DRMS  500  to return to the DRMS  500  or converge with other microvehicles  1010  to close the net sections (tantamount to drawing the drawstring on a bag) and thereby retain any space debris that has been captured in the net sections. In the illustrated embodiment, the microvehicles  1010  are commercially available, e.g., from SpaceQuest, Ltd, of Fairfax, Va. Alternative embodiments employ conventional microvehicles that are commercially available from other manufacturers or later-developed microvehicles. 
     It should also be noted that  FIG. 10 , like the FIGs. before it, do not show the doors on the microvehicle housings  630  for the sake of clarity. One embodiment of such doors will now be illustrated and described.  FIG. 11  is a portion of the isometric view of  FIG. 7  showing doors  1110  of the microvehicle housings  630  of  FIG. 10  in an open state. The illustrated embodiment of each door  1110  exists in a single piece, hinged on one side. In the embodiment of  FIG. 11 , the DRMS  500  is configured to command the doors  1110  to open as needed to allow the microvehicles  1010  to be ejected or protect the microvehicles  1010  from damage. 
       FIG. 12  is a portion of the isometric view of  FIG. 7  showing the microvehicles  1010  ejecting from their respective microvehicle housings  630  to deploy corresponding net sections. For clarity&#39;s sake, only one of the microvehicle housings  630  and doors  1110  is referenced in  FIG. 12 . 
     As is apparent, the microvehicles  1010  have been ejected from their microvehicle housings  630  and are traveling in a generally straight line directly radially outwardly from the microvehicle housings  630 . In one embodiment, ejection of the microvehicles  1010  is carried out using potential energy stored in a spring located in each of the microvehicle housings  630 . In the illustrated embodiment, ejection of the microvehicles  1010  is carried out using the propulsion systems in the microvehicles  1010 . As is also apparent, each of the microvehicles  1010  is tethered to a leading edge portion (unreferenced) of a corresponding net section  640 , as evidenced by the leading edge portion unfurling. A tether couples the microvehicles to their respective leading edge.  FIG. 12  shows, but does not reference, the tethers for clarity&#39;s sake. 
     In various embodiments, the DRMS  500  directly controls the microvehicles  1010 . In other embodiments, the microvehicles  1010  are semi- or fully autonomous. In certain embodiments, the microvehicles  1010  are scalable in terms of size and/or number per net section depending on the size of each net section to be deployed. 
       FIGS. 13-15  show various phases in net section deployment.  FIG. 13  is a further isometric view of a portion of the DRMS of  FIG. 5  showing the microvehicles  1010  ejecting from their respective microvehicle housings to deploy corresponding net sections.  FIG. 13  is presented primarily for the purpose of illustrating tethers  1310  that couple the microvehicles  1010  to leading edges of corresponding net sections  640 .  FIG. 14  is yet a further isometric view of a portion of the DRMS of  FIG. 13  showing the microvehicles ejecting from their respective microvehicle housings to deploy corresponding net sections  640 .  FIG. 15  is a plan view of one of the microvehicles  1010  of  FIGS. 13 and 14  deploying a corresponding net section  640 . 
       FIG. 16  is an isometric view of the DRMS of  FIG. 5  showing the net thereof in a fully deployed state.  FIG. 16  demonstrates that, at least in the illustrated embodiment, the overall size of the net sections  640  dwarfs the DRMS  500 . The result is that a relatively large space debris collection area is presented for use. 
       FIG. 17  is an elevational view of the DRMS of  FIG. 5  showing the net thereof in the fully deployed state.  FIG. 17  is presented primarily for the purpose of showing the relationship of the net sections  640  to the DRMS  500 . 
       FIG. 18  is a portion of the elevational view of the DRMS of  FIG. 5  showing the net thereof in the fully deployed state.  FIG. 18  is presented primarily for the purpose of showing that the deployed net sections  640  clear the upper and lower enclosure fairing sections  620 ,  730 . 
       FIG. 19  is an isometric view of the DRMS of  FIG. 18  approaching an example of a piece of space debris, namely a spent upper stage  1910  of a launch vehicle. In fact,  FIG. 19  shows a Centaur, which has a nominal diameter of about 10 ft. This relatively large diameter is still small when compared to the size of the net sections of the DRMS  500 .  FIG. 20  is an isometric view of the DRMS  500  of  FIG. 18  coming into contact with the spent upper stage  1910 . At or near contact with the spent upper stage  1910 , the DRMS  500  commands the microvehicles to close the net sections, perhaps by converging with each other to close the net sections and thereby retain the spent upper stage  1910 . In one embodiment, the DRMS  500  then moves to a safer location. In a more specific embodiment, the DRMS  500  de-orbits and reenters the atmosphere to destroy itself and the spent upper stage  1910 . 
       FIG. 21  is a flow diagram of one embodiment of a method of operating a DRMS carried out according to the principles of the invention. The method begins in a start step  2110 . In a step  2120 , a plurality of upper enclosure fairing sections are opened. In a step  2130 , a plurality of lower enclosure fairing sections are opened. In a step  2140 , a plurality of microvehicles are caused to be ejected relative to a frame of a DRMS, perhaps from a corresponding plurality of microvehicle housings. In one embodiment, the microvehicles are deployed using propulsion units in the microvehicles. The plurality of microvehicles are tethered to a corresponding plurality of net sections. In a step  2150 , the corresponding plurality of net sections are consequently caused to be deployed, perhaps from a generally cylindrical roll. The plurality of net sections cooperate to form a net configured to capture space debris. In a step  2160 , the space debris is intercepted. In a step  2170 , the plurality of microvehicles are commanded to close the net sections. The DRMS can then move to a safer location, perhaps de-orbiting and reentering the atmosphere to destroy itself and the space debris. The method ends in an end step  2180 . 
     Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.