Pincer apparatus for nanosat transport across a satellite

A pincer system is comprised of an array of pincers. Each pincer includes an inner disk having legs that are pushed downwards onto a pliable material to cause protuberances, while an outer disk is rotated to simultaneously squeeze the extruded material between its legs and those of the stationary inner disk. Tracks provide for slideable movement of the individual pincers. The system, carrying an attached micro-satellite, translates across a pliable material covering a spacecraft by coordinating the movement of the pincers with their grasping of the pliable material. This abstract is provided to comply with the rules requiring an abstract, and is intended to allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.

BACKGROUND OF THE INVENTION

The present invention is related to a method and apparatus for performing maintenance and repair on the outer surface of a satellite while the satellite is in orbit. More particularly, the present invention is comprised of movable pincers for latching onto the pliable protective fabric covering the satellite and moving the invention across the fabric, whereby the invention can carry and transport a proximity repair micro-satellite across the fabric to a location requiring repair or maintenance.

Satellites begin to deteriorate after launch, whereupon they are exposed to the deleterious effects of cosmic radiation, solar winds and electro-magnetic radiation while passing through the Van Alen belt. Over time, flecks of space debris may damage the satellite's surface. Continued damage may ultimately corrupt the satellite's hardware and electronic systems. Since there are no means to effect repairs or perform maintenance, satellite components will inevitably begin to malfunction or fail entirely. Depending on the system, the foregoing could render a satellite useless. Thus, for want of a minor repair or routine maintenance, a multi-million dollar satellite could be rendered useless and reduced to orbiting space junk.

Multi-layered insulation (hereinafter called “MLI”) is a manufactured material used to cover nearly the entire body of objects placed in orbit, i.e., satellites, and is presently the only known means of providing limited protection to such objects. MLI reflects harmful incident radiation, and also insulates the object from the cold of outer space by using multiple radiation-heat transfer barriers to retard the flow of energy that would otherwise cause damage. Beta cloth is one example of an MLI. It is an inorganic, fiberglass woven cloth impregnated with Teflon® polytetraflouroethylene resin (Teflon is a registered trademark owned by DuPont), and perforated to prevent ballooning. As an outer cover, the Beta cloth MLI has a nominal thickness of 0.008 inches and is rated with a tensile strength of about 90 lb/inch against warping. Its minimum shear strength is 1.8 pounds and it can maintain the foregoing tensile and shear strengths at a temperature of up to 400° F. However, regardless of its composition, MLI is not impermeable, and damage to the satellite nonetheless occurs. Maintenance of an orbiting satellite would also enhance its longevity.

The XSS Micro-satellite series is the Air Force Research Laboratory's sequence of on-orbit experiments to develop a logistics and servicing capability for orbiting satellites. As the name would imply, micro-satellites (hereinafter referred to as “nanosats”) are small, agile and compact. They are fully equipped with on-board avionics, propulsion and high-resolution cameras allowing a highly maneuverable nanosat to perform close-proximity inspection. It is the intent of aerospace leaders to expand the capability of such nanosats to include task-specific resources and tools, thereby providing it with the capability to perform maintenance and repair. Such modification of nanosats would permit them to extend the life and performance of an orbiting satellite at substantially less cost, and in less time, than by preparing and launching a replacement satellite from the earth.

Whatever the specific form or composition of the MLI, this protective fabric should provide a medium having sufficient pliability for the present invention to grasp onto and provide transport for a nanosat across the exterior of an orbiting satellite, as will be hereinafter discussed in detail.

Despite the availability of MLI as a means of protection for satellites, there is still a need in the art for means to perform exterior maintenance and repair while the satellite is in orbit. The present invention provides means for transporting a nanosat capable of performing maintenance and repair, across the MLI covering an orbiting satellite. The present invention thus fulfills the aforementioned need in the art.

SUMMARY OF THE INVENTION

Briefly, the present invention is comprised of a pincer system for physically attaching to and maneuvering over the pliable protective material covering a satellite, without damaging the material. A proximity-repair nanosat is carried by the pincer system over the material, allowing the nanosat to locate, assess and/or repair damage to a satellite's protective covering material, the satellite surface underlying the protective material, or its exterior components.

An array of pincers is slideably attached to tracks, wherein the tracks allow independent translation of the pincers along the pliable material's surface. Locomotive means for the pincers are contained in the tracks. In one embodiment, each pincer is comprised of a set two nested disks adapted to simultaneously pinch and twist the pliable protective material covering a satellite and thereby grasp it, without damaging the material. The array of pincers, and thus the entire apparatus and the attached nanosat, is maneuvered across the protective material by coordinating the translation of the pincers along their respective tracks with their grasping of the protective material.

DETAILED DESCRIPTION

Turning to the drawings,FIG. 1illustrates pincer system11of the present invention, in conjunction with nanosat13, undertaking an inspection and repair on orbiting satellite15. Nanosat13is a micro-satellite having resources and tools for inspecting space vehicles, performing maintenance on them and, depending on the extent of the damage, also making repairs. Satellite15is covered by pliable multi-layered insulation17, hereinafter called “MLI”17. Tear19in MLI17evinces damage to the underlying structure of satellite15. Nanosat13can be removably attached to pincer system11. Pincer system11is shown traversing MLI17while carrying nanosat13to tear19in MLI17.

FIG. 2is a bottom view of pincer system11, showing its underside, i.e., the part of system11in contact with MLI17. Pincer system11includes track assembly21, comprised of tracks23and25, together with pincers27,29,31and33. Pincers27and29are slideably mounted on track23, while pincers31and33are slideably mounted on track25. Tracks23and25are attached where they intersect; they neither rotate nor translate with respect to each other. Although shown as being perpendicular, the angle of intersection between tracks23and25may be varied to suit particular circumstances. Pincers27,29,31and33may each be individually moved relative to their respective tracks by means of a worm gear, a chain and sprocket (neither of which are shown) or other means of locomotion well known to those skilled in the mechanical arts. Pincers27,29,31and33are each capable of alternately grasping and releasing MLI17, as will subsequently be explained in detail.

Pincer system11can be moved across MLI17to any location by using the ability of a selected pair of pincers to alternatively grasp and release MLI17, with the locomotive means engaging the grasping pincer to force translation of the track relative to the grasping pincer. The foregoing is best explained by the following example.

To move towards tear19, pincer system11would first move to the right and then upwards (or first upwards and then to the right). To move to the right, pincer29initially grasps MLI17, while pincer27is not grasping MLI17(the neutral mode). Pincers27,31and33remain in the neutral mode while pincer system11is moving to the right. The locomotive means for track31is actuated to engage pincer29and pull track23through pincer27to the right until pincer29abuts track25(or a lesser distance if desired).

To proceed further to the right, pincer27(or pincers31and33) are engaged to grasp MLI17, while pincer29is placed in the neutral mode and moved by the locomotive means to the right, until it reaches end37of track23(or a lesser distance if desired), whereupon it grasps MLI17and pincer27(or pincers31and33) are placed in the neutral mode. The locomotive means for track23is actuated to engage pincer29and again pull track23through pincer29until pincer29abuts track29. The foregoing sequence is repeated until pincer system11is translated the desired distance to the right.

Translation of pincer system11relative to MLI17to the left would be achieved using the same sequence of steps with pincer27acting in concert with track23, with pincer29(or pincers31and33) acting to keep track assembly21stationary while pincer21is being moved in the neutral mode. Translation up, i.e., towards tear19, is achieved using the aforementioned sequence of steps with pincer33acting in concert with track25, with pincer31(or pincers27and29) acting to keep track assembly21stationary while pincer33is being moved in the neutral mode. Translation down would be achieved using the aforementioned sequence of steps with pincer31acting in concert with track25, with pincer33(or pincers27and29) acting to keep track assembly21stationary while pincer31is being moved in the neutral mode.

Alternative track assemblies can be employed to enable nanosats to navigate around sharp corners on a spacecraft. Moreover, use of flexible, nonlinear tracks in conjunction with the pincers of the present invention could provide the ability to transport a nanosat over an uneven surface.

FIG. 3is a partially sectioned front view of pincer27, a pincer of the present invention. Pincer27includes housing40, which is slideably attached to track23(not shown) by means of brackets41. Housing40is also attached to the locomotive means (not shown) for track23, which provides for translation of pincer27along track23. Pincer27includes disks42and44.FIG. 4is a cross-sectioned front view of pincer27, with housing40removed.FIG. 5is a perspective view of disk42andFIG. 6is a perspective view of disk44.FIGS. 7 and 8respectively show bottom and front views of disk42.FIG. 9is a bottom view of disk44.

As shown in the aforementioned figures, disk42includes six legs46that are equidistantly spaced apart from one another, with each leg having a foot48. Disk44includes six legs50that are equidistantly spaced from one another, with each leg having a foot52. Although six legs are shown for each disk, it should be noted that the present invention will function in a manner consistent with the teachings herein where there are more or fewer legs per disk. As illustrated by the perspective view provided byFIG. 10, disk44is nested within disk42.FIG. 10shows disks42and44in their completely open, neutral position, i.e., not grasping MLI17.

To engage, or grasp, MLI17, feet52are pressed down into MLI17, causing protuberances of the material around the feet. As shown inFIG. 11, disk42is then rotated clockwise relative to stationary disk44.FIG. 12shows disks42and44in the fully engaged position, with each of legs46brought into near abutment with the corresponding leg50that opposes it and thereby limits its rotation. This near abutment captures and squeezes the extruded portion of MLI17between legs46and50(it is not complete abutment only because the extruded portion of MLI will lie between legs46and50). Both disks42and44can be further rotated together after they have secured MLI17between their respective opposing legs to form a stronger hold on the fabric.

The remaining parts of pincer27cooperate to obtain the aforementioned pressure of feet52against MLI17, and the of rotation of disk42relative to stationary disk44in order to effect their engagement. More particularly, rubber pads60of housing40are first moved into contact with MLI17while disks42and44are in an open state. The opposing resistive force of underlying satellite15acts against pads60. Spring62is captured between annular retaining collar64and annular spring retainer66. Housing40is mounted on retaining collar64. Thus, housing40is free to move upward until the initial distance between retainer66and stop block68has been taken up, whereupon the compressive spring force opposes further upward travel. The resistive force of underlying satellite15prevents the further downward travel of pads60, and exposes feet48and52, allowing them to come into contact with MLI17.

As shown inFIG. 4, retaining sleeve69sits between retaining collar64and spring retainer66. Shaft70passes through an annular hole in the center of spring retainer66, through a cylindrical bore in retaining sleeve69, through an annular hole in the center of retaining collar64, and through annular hole72in the center of disk42. Shaft70includes races76that accommodate ball bearings78. The foregoing openings, together with ball bearings78, allow the axial rotation as well as the vertical translation of shaft70relative to retaining collar64, spring retainer66and retaining sleeve69. Retaining sleeve69, retaining collar64and disk42are bracketed to each other. Disk42is thus also free to rotate about, and translate vertically relative to, the axial axis of shaft70. Retaining collar64also includes grooves79.

Camshaft80includes cam82. Shaft70includes shaft top84and shaft bottom86. Shaft bottom86rests in annular cavity88in the top of disk44. Cam82and shaft top84are mechanically engaged and shaped such that the rotation of camshaft80, and therefore cam82, creates a downward force on shaft top84, shaft70, and disk44. This results in disk44, and thus feet52, being slowly pressed against MLI17, causing the material to form protuberances about feet52.

As camshaft80is rotated, disk42is simultaneously rotated by force applied by metal tabs (not shown) inserted into grooves71. Disk42is rotated clockwise approximately 32°, until its legs46abut legs50of stationary disk44, thereby capturing the protuberances occurring around feet52. As previously noted, both disks42and44can be subsequently rotated together to strengthen their hold on the extruded MLI17.

It is to be understood that the preceding is merely a detailed description of an embodiment of this invention, and that numerous changes to the disclosed embodiment can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. The preceding description, therefore, is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents.