Title:
Solar wing and tether mechanisms for asteroid uncooperative docking and asteroid orbit adjustments
Kind Code:
A1


Abstract:
A space craft docks with a target, such as an asteroid utilizing a tether shaped in a loop. The loop is positioned about a portion of the asteroid and retracted thereby docking the space craft to the target. A deployable wing may then be inflated and filled with foam. The wing has a reflective surface which assists in generating a larger momentum from impending photons. The wing may be moved relative to the space craft to alter the forces acting on the wing, and thus the target. These forces are utilized, over time, to alter the orbit of the target. Sensors and communication equipment may be utilized to allow remote operation of the wing and tether.



Inventors:
Campbell, Jonathan W. (Harvest, AL, US)
Application Number:
09/923260
Publication Date:
02/06/2003
Filing Date:
08/06/2001
Assignee:
CAMPBELL JONATHAN W.
Primary Class:
Other Classes:
244/172.4, 244/158.3
International Classes:
B64G1/40; B64G1/64; (IPC1-7): B64G1/62
View Patent Images:
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Primary Examiner:
COLLINS, TIMOTHY D
Attorney, Agent or Firm:
NASA/MARSHALL SPACE FLIGHT CENTER (MSFC, AL, US)
Claims:

Having thus set forth the nature of the invention, what is claimed herein is:



1. A space craft capable of docking with a target, said space craft comprising: a tether, said tether deployable from the space craft to form a loop of a first circumference in a space environment; wherein retraction of the t said tether retractable relative to the space craft so that said loop forms a second circumference, said first circumference greater than said second circumference, and ether docks the space craft to the target.

2. The space craft of claim 1 wherein said second circumference approximately equivalent to an outer circumference of a portion of the target.

3. The space craft of claim 1 further comprising thrusters for manuevering the space craft in the space environment to position the loop of the tether about a portion of the target.

4. The space craft of claim 1 further comprising sensors for evaluating the position of the tether in space.

5. The space craft of claim 4 further comprising communications equipment to report and receive information related to the docking process.

6. The space craft of claim 1 further comprising an anchor for securing the space craft to the target.

7. The space craft of claim 6 wherein the anchor is screw driven.

8. The space craft of claim 6 wherein the anchor is explosively driven.

9. The space craft of claim 1 wherein the tether is comprised of a ribbon having ribs.

10. The space craft of claim 1 further comprising a deployable wing, said wing capable of altering the orbit of the target when deployed.

11. The space craft of claim 1 wherein the space craft is an Earth launched satellite.

12. The space craft of claim 1 wherein the target is an asteroid.

13. A space craft for adjusting the orbit of a target, said space craft comprising: a deployable wing connected to and moveable relative to the space craft when deployed in a space environment; and an anchor securing the space craft to the target.

14. The space craft of claim 13 further comprising communication equipment on the spacecraft for transferring commands to the space craft from a remote location to move the wing relative to the space craft to adjust the orbit of the target.

15. The space craft of claim 13 wherein the wing further comprises a highly reflective exposed surface on the wing.

16. The space craft of claim 13 wherein the wing is an inflatable solar wing.

17. The space craft of claim 16 wherein the solar wing is inflated and filled with foam.

18. The space craft of claim 13 further comprising a tether deployable from the space craft to form a loop of a first circumference in a space environment; said tether then retractable relative to the space craft so that said loop forms a second circumference, said first circumference greater than said second circumference, wherein retraction of the tether docks the space craft to the target.

19. A method of changing the orbit of a target comprising: a. locating a space craft in the vicinity of a target in a space environment; b. deploying a tether from the space craft to form a loop of a first circumference, said first circumference greater than a circumference of a portion of the target; c. positioning the loop about the portion of the target; d. retracting the tether to dock the space craft to the target; e. providing a wing from the space craft to deflect the orbit of the target.

20. The method of claim 19 wherein the step of providing a wing further comprises deploying an inflatable wing from the space craft with a reflective surface, said wing acted upon by photon energy to alter the orbit of the target over time.

Description:

ORIGIN OF THE INVENTION

[0001] This invention was made by an employee of the United States Government and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon or thereof.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to an apparatus and method for docking a satellite to an asteroid using a tether, and with the satellite docked, deploying a wing to adjust the orbit of the satellite.

[0004] 2. Prior Art

[0005] Asteroids with orbits around the Sun which could cross the orbit of the Earth pose a risk. Presently, there have been no known efforts made to adjust the orbits of asteroids to avoid the possibility of an asteroid entering the Earth's atmosphere, striking the Earth, and causing serious problems.

[0006] Photons are known to exert a pressure on a surface upon contact. A need exists to harness this energy to adjust the orbit of asteroids, or other objects in a space environment.

[0007] Tethering technologies are maturing and have been demonstrated in space. However, no effort is believed to have been made to tether a satellite to an asteroid.

[0008] Inflatable structure technology is a maturing area. A need exists to deploy an inflatable wing on an asteroid to utilize photon pressure acting on a moveable wing to adjust the orbit of the asteroid.

SUMMARY OF THE INVENTION

[0009] Consequently, it is a primary object of the present invention adjust the orbit of an asteroid.

[0010] It is a further object of the present invention to deploy a wing delivered by a satellite to adjust the orbit of the asteroid.

[0011] Another object of the present invention is to tether a satellite to an asteroid in order to dock the satellite with the asteroid.

[0012] Accordingly, the present invention provides a satellite for docking with an asteroid. The spacecraft is launched to intercept a target, such as an asteroid, comet or other orbiting body. Onboard thrusters on the spacecraft may be utilized to synchronize the orbits of the spacecraft and the target. A tether loop is preferably deployed from the spacecraft with the loop having a diameter larger than the target. With the loop appropriately positioned about the target, the tether is retracted to connect the tether to the target. The tether is then further retracted until the space craft is docked against the target.

[0013] Once the space craft is docked, other anchoring mechanisms may be deployed to secure the spacecraft to the target. A wing is then deployed from the space craft. The wing is preferably inflatable and may be filled with foam for additional rigidity. The wing may be moved relative to the target so that photon pressure acting against the wing propels the target in a desired manner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The particular features and advantages of the invention as well as other objects will become apparent from the following description taken in connection with the accompanying drawings in which:

[0015] FIG. 1 is a diagramic view of a space craft with a tether loop deployed about a target;

[0016] FIG. 2 is a close up view of the tether material of FIG. 1;

[0017] FIG. 3 is a diagramic view of the space craft secured to a target with a wing deployed in a first position;

[0018] FIG. 4 is a diagramic view of the space craft with the wing deployed to a second position; and

[0019] FIG. 5 is a diagramic view of the orbit of the earth about the sun with two orbits of a target about the sun.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Referring to the FIG. 1, a space craft 10 is illustrated deploying a tether 12 about a target 14. Space crafts 10 may include any acceptable vehicle utilized to travel from one point to another in space including satellites. It is anticipated that space craft 10 could be deployed from rockets launched from the earth or from other space craft 10. Targets 14 may include asteroids, comets, or other body in space which the orbit is desired to be adjusted.

[0021] The tether 12 forms a loop about the target 14. A detailed view of the tether 12 is illustrated in FIG. 2. The tether 12 may be constructed in a ribbon of fabric such as from an aramid fiber such as Kevlar™ or from other suitable materials. The tether 12 may have rigid ribs 16 to assist in the maintaining the loop rigid during deployment. It is anticipated that the tether 12 will halite a width of about one to two inches and a thickness of about {fraction (1/16)} of an inch, somewhat similar in dimensions to typical electricians tape, however, other tether material could also be utilized.

[0022] As shown in FIG. 1, when the space craft 10 approaches the intended target 14, the tether 12 is deployed to form a loop. Loops could be as large as several kilometers, if necessary. The loop should be greater in circumference than the circumference portion of the target 14 to be retained. The space craft 10 could then maneuver, if necessary, to locate the loop about the target 14.

[0023] Onboard sensors on the space craft 10 could be utilized to evaluate the position of the loop relative to the target 14. When desired alignment is achieved, the space craft 10 may begin to retract the tether 12 to tighten the loop about the target 14, such as be winding the tether 12 on a reel. As the loop is retracted, the space craft 10 is docked to the target 14.

[0024] Once the space craft 10 is sufficiently close, preferably contacting the target 14, additional anchors may be employed to secure the space craft 10 to the target 14. Additional anchors may include explosive driven, screw driven, or other appropriate anchors.

[0025] With the space craft 10 connected to the target 14, a wing 18 or more specifically, a solar wing, may be deployed and positioned as illustrated in FIGS. 3 and 4. The wing 18 may be inflatable and inflated to the deployed position. During the inflation process and/or once inflated, the wing 18 may be filled with foam or other appropriate material for additional rigidity. The exposed surface 20 of the wing 18 may be silvered or otherwise made to be reflective such as by applying a thin film to the surface 20. A suitable wing 18 may be constructed from kapton™ or other suitable material which is sufficiently light weight, but can be utilized to have a relatively large surface area.

[0026] With the wing 18 deployed, the target 14 may now be maneuvered. Specifically, the wing 18 is struck by photons 22 from the sun 24. The photons 22 impart a force to the wing 18. In FIG. 3, the photons 22 strike the wing 18 to move the target 14 in the direction of the photon movement, i.e., downwardly.

[0027] In FIG. 4, the wing 18 is angled. A wing movement mechanism of the space craft 10 is utilized to move the wing 18 to the position shown in FIG. 4. An exaggerated thrust diagram 26 is shown in FIG. 4 showing that the target 14 would move downwardly as well as to the left over time due to the wing 18 position. Sensors and transmitters/receivers may be utilized to provide information to and from a station on Earth, or elsewhere, for the coordination of docking, wing 18 deployment, as well as wing 18 movement to direct the target 14 to a desired orbit if not controlled from the space craft 10 itself. Ground control, or other appropriate controller, may move the wing 18 to a desired position. Solar panels may be provided with the space craft 10 to provide electrical power to the sensors and communication subsystems of the space craft 10.

[0028] The forces of the impending photons 22 may be calculated using Newton's Second Law, F=ma. Force=change in momentum divided by the time interval. The change in momentum is the momentum transferred to the mirror during the time interval. Electromagnetic energy is transferred through radiation. Maxwell showed that momentum delivered to an object through radiation is equal to the electromagnetic radiation divided by the speed of light, p=U/c. When the photon is totally reflected by the object, then the momentum imparted is doubled, p=2 U/c. This phenomena has been documented in carefully controlled experiments, as well as observed in nature (i.e., the tail of a comet always points away from the sun due to radiation pressure).

[0029] Solar pressure from the sun is approximately equal to 1.00×10−5 N/m2. For a circular wing 18 which is 1 Km in diameter, the radius would be 500 meters. The wing area would be 7.85×105 m2 (i.e., area=Pi×r2). An asteroid having a density of 10 kg/m3 and a radius of 500 meters would have a volume of 5.24×108 cubic meters (volume=4/3×Pi×radius3), and an acceleration of 1.5×10−9 m/s2 (m/s2)=(P×A)/(rho×V) due to the photon 18 force.

[0030] Accordingly for an acceleration period of 1 year (3.15×107 seconds), the asteroid would be deflected 7.46×105 meters; for 2 years, 2.98×106 meters; for 3 years, 6.71×106 meters; and 10 years, 7.46×107 meters. Therefore, in just three years, an asteroid which originally was going to strike the dead center of the Earth could be deflected enough to completely miss the Earth by the appropriate use of a wing 18.

[0031] FIG. 5 shows a first orbit 28 of an asteroid about the sun 24. The first orbit 28 of the asteroid intersects the earth's orbit 30 at collision points 34. If the earth and the asteroid were to be at the collision points 34 at the same time, severe consequences could occur. However, by utilizing the space craft 10 with the wing 18 of FIGS. 1, 3 and 4 which may be docked with tether 12, the first orbit 28 of the asteroid may be altered to second orbit 32 to avoid any possibility of future problems with the earth's orbit 30 about the sun 24 conflicting with the asteroid orbit about the sun 24.

[0032] Numerous alternations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to the preferred embodiment of the invention which is for purposes of illustration only and not to be construed as a limitation of the invention All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.