TRANSPORT AND ARCHIVING

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of provisional application number 62/523432 filed on June 22, 2017 and provisional application number 62/631213 filed on February i 5, 2018

STATEMENT RELATED TO FEDERALLY SPONSORED RESEARCH OR

DEVELOPMENT

Provisional Application 62/523432

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to acquisition, transport, archiving, and beneficiation of space mineral resources, including the acquisition of samples for scientific investigations on Earth or on orbiting space stations. More specifically, the present invention employs a series of orbiting tether stations, operating in concert with very specialized end-effectors which integrate with the tether apparatus to gather samples or bulk quantities of space mineral resources in zero-g, fractional ~g, or multiples of Earth gravity environments. Gathered samples can be archived, beneficiated, or transported in bulk on the orbiting tether spacecraft which can propel itself in space anywhere in Interplanetary space. Alternatively, the archived or bulk samples may he transferred to another spacecraft for transport to a distant receiving station for future use, enabling the orbital tether spacecraft to continue operations.

Another use of this apparatus is to transport bulk materials from one place on a celestial body to another without need for a surface transportation system, dramatically reducing costs to support in-situ resource utilization, and greatly enhancing the utility of a centralized processing location. Furthermore, the apparatus may be used to transport refined materials to distant locations on a celestial body where they may be utilized effectively.

2 Background

Current sample return missions are very complex affairs. Indeed the proposed Mars Sample Return Mission requites three missions and three separate spacecraft, and its proposed cost is - $&B in order to return 3Q0 gram of samples from a single location. Tlte reason Is that one spacecraft con tains a tender, and perhaps a rover to collect and archive a sample front a single location on the celestial body. Another spacecraft is landed which contains a small rocket launcher into whose payload bay the sample is inserted. This launcher" is launched to coincide roughly with the orbital position of a third spacecraft which will rendezvous and transfer the sample container and return to Earth, This sequence of events can vary depending upon the depth of the surface gravity well from which the sample is being collected. The greater the gravity well, the smaller the sample and the greater the mission’s complexity and cost.

As a concrete example, NASA JFL’s Mars Sample Return Mission is comprised of three separate payloads, Payload 1 is the Mars Science Laboratory, which is capable of gathering a sample from a limited geographical region and places it in a sample container. The Mars Sample Return Lander is a separate mission and contains the Mars Ascent Vehicle Into which the spherical sample container would be placed. The third mission is the Mans Sample Return Orbiter, which would rendezvous with the spherical container, retrieve it and carry it back to Earth tor analysis. The mission is startlingly complex and carries high risk of More doe to the myriad of tasks which must be 100% successful.

The concept of using a tether to capture and return samples is not new; a very embryonic concept is described in NASA’s space tethers handbook. Tins concept is substantially different from the proposed invention as it. requires a lander. It differs from this concept in that some form of explosive or compressed gas or spring system is required to force the penetraior into the surface in order to collect the sample. The sample material is supposed io enter the sample through holes in the container which is then explosively sealed. This concept presumes a great deal about the target of the sample return with little a priori information:

1. Hardness of the body ^; s surface

2. Granule size of the sample material

3. How the solid sample container is removed if the penetrator has buckled from impact Technically, the proposed concept provides insufficient insight as to how actually build it; however, the concept is in the open literature. Concepts described for sample returns in the open literature, or those reduced to practice operate in a gravity well so that certain transfer operations of the sample can occur under the influence of gravity, consequently, a sample container can he filled from a sample collector under the influence of gravity. Even a very modest gravity field, such as the Moon’s with a gravitational acceleration of ~.16g provides Sufficient force to empty or fill containers without resorting to affirmative techniques.

Brief Summary-Primary Embodiments

There are two primary embodiments to the proposed invention which are based on an orbiting space tether concept. While functionally similar, they are operationally very different. The first concept. Figure I , involves a rotating momentum exchange type of tether, although the purpose of this tether is not primarily to impart momentum to the captured sample. In the graphic above, the rotating tether is comprised of a rotating main spacecraft station means (I) which contains all the elements of a spacecraft, such as power, attitude control, main propulsion, energy storage, and at least one winching station to extend and retract the extensible tether cable means (3) lower winch station and the counterweight means (2), The rotating tether is placed in some desired orbit around the celestial object from which the sample is to be taken with an orbital velocity Vo at an altitude of ~R. The main station is set into rotating motion such that the product of the rotational rate times R is the orbital velocity, with a rotation vector such that when the lower winch station is nearest the- celestial object's surface, the product of the rotational rate and the tether cable length R, taXR is approximately equal to the orbital velocity, but in the opposite direction to the orbital velocity vector at the nadir location. This yields a condition where the lower winch station means (4) is relatively untnoving with respect to the object’s surface. The altitude, hence R and the rotational rate _: can be modified to account for the rate of rotation of the object or planetary surface.

Consequently, as the tether rotates, the lower tether station has an apparent motion perpendicular to the body 's surface, and can allow the release of various end effectors for collection of samples without substantial maneuvering required of the lower winch station for a short duration. Various orbital inclinations are feasible for various missions. For example, if the tether sample system Is used to gather samples or to relocate vital resources from one location on the planet to another and the locations are on or near the equator, an equatorial orbit is optimum. For prospecting for samples globally, a polar inclination is likely of greatest benefit. The lower winch station means (4) contains most elements of a spacecraft, including attitude and reaction control, power, structure, and a smaller winching means to lower a secondary tether means (7) which can operate independently or in concert with (3), to which is attached one of several types of end effector means (5) for gathering or transporting samples.

Figure L Rotating Sample Tether with Lower Winch Station

The second embodiment manifests a gravity gradient stabilized tether. Figure 2, which may be structurally similar to the rotating tether. This embodiment contains a main tether spacecraft station means (1).

Figure 2. Gravity Gradient Stabilized Orbiting Tether with Lower Winch Station and

Em! Effector

The main spacecraft contai ns all the elements of a spacecraft, such as power, attitude control, main propulsion, energy storage, and at least one winching station to extend and retract the extensible tether cable means (3) lower winch station and the counterweight means (2). The rotating tether is placed in some desired orbit around the celestial object from which the sample Is to he taken with an orbital velocity V, rat an altitude of HR, The spacecraft’s orbital velocity is dependent only on the object’s mass and the station altitude. Specific cases are enumerated within the body of this document. Because the power portion of the tether circumscribes a smaller path length than the upper orbital path in the same orbital period, the velocity of the lower station with respect to the surface is lower by a calculable amount Any residua! motion of the lower winch station means (4) and end effector means (5) need to he removed by the on-board reaction control sy stem of the lower winch station.

Description of Lower Winch Station & End Effectors The sample gathering means of the invention are implemented by a series of end effectors. While similar in design, in some eases to terrestrial counterparts, all terrestrial mechanisms for excavating or gathering samples depend upon gravity for removal or transfer of gathered material. In space, particularly while in orbit or even on the surface of some celestial bodies, such as asteroids, their mass is insufficient to provide a useful gravitational field, hence gravity is not a dependable means for organizing sample recovery and transport when in space.

Lower Winch Station

The lower winch station means (4) is shown conceptually in Figure 3,

Figure 3. Lower Winch Station

The lower winch station means (4) is comprised of energy storage means (8), with a preferred embodiment of Lithium-ion bateries, in this concept, three energy storage devices are shown, The station is comprised of an external structure means (9) which is used to mount all of the interna! and external components and to connect the lower winch station to the extensible cable means (3). There exist radar sensor means (10) which measures lateral velocity so that the sample gathering means can be stationary with respect to the: surface. There exists an imaging sensor means to image the surface or items on the surface mounted to the lower portion of the structure, A communications means i s conta ined within the structure to communicate necessary information to the main spacecraft station. Four lateral reaction control thruster means (1 1) provide a method to eliminate lateral motions so the end effectors can impact the surface with only vertical motion. A lower winch drum and motoring means ( 12) is used to raise and lower the end effectors which actually collect samples. The lower winching means (i 2) is mounted to the exterior structure means (9) with winch mounting structure means (13). A plurality of sample collecting end effectors can he mounted to the bottom of the external structure means (9) which can be used to collect a plurality of samples each time the lower winch station means is lowered toward the surface.

Operations

The lower winching station (4) is released from the main spacecraft tether station means (1). For the rotating tether means the winching station means is extended as the entire system is “spun-up” to its desired rotational velocity. For the gravity-gradient stabilized means, the extensible tether means (3) is simply lowered toward the surface until the desired height above the surface Is attained.

In the rotating tether means, the lower winching station begins collection operations when the station is within --i-10° of actual nadir. The sensors aboard the lower winch station locate the desired sample location and the on-board processor means calculates when to release the braking mechanism on the lower winch means so the sample collecting end effector impacts the desired location,

The gravit) gradient stabilized means respires the lower winch station to engage the reaction control thrusters to move the lower winch station forward along the path traced along the ground, and once the desired distance has been achieved, the thrusting is managed to hold the lower winch station in a stationary position, the sample end effector is released, the sample gathered, and the collector is recovered, Sample end effectors from the plurality of those mounted on the exterior structure may be replaced to gather a plurality of samples.

End Effectors

Clamshell Excavator: The clamshell excavator is shown in Figure 4. The clamshell excavator Is designed to collect bulk samples in either a gravity or 0-g/micro-g environment

Figure 4. Clamshell Excavator

The clamshell excavator operates in much the same fashion as terrestrial clamshell excavator does with key modifications to enable operations in zero or micro- gravity environments.

The clamshell excavator means (Figure 4) is comprised of a. connection means ( 14) to connect the clamshell excavator means _. to the lower winch cable means (7), The clamshell bucket is forcibly opened and closed by a pair of electromechanical actuators (15). The clamshell bucket is comprised of a pair of section means (17) which contain a flexible liner means ( 18) (shown later).

Clamshell Liner: The clamshell finer means is a flexible liner designed to contain collected samples in a realistically leak-resistant, flexible container as shown in

Figure 5.

Figure 5, Clamshell Liner The clamshell finer means ( 19) is made from an impervious semi-flexible material or fabric which is conformal to the inner geometry of the metallic clamshell bucket means. The upper portion of the liner contains magnetic attachments to hold the liner in place at the top portion of the bucket sections. The liner has a pivot point means at (21). The liner has a toothed or smooth magnetic leading edge means (22), which holds the liner in place at the bucket jaw leading edges, and when the bucket is closed with the sample inside, the magnetic leading edge seals the container closed and traps the sample inside without releasing the contained sample material . When the bucket is opened, the sealed container can be removed and place hi storage with some mechanical device and stored as required.

Long Rod Penetrator Sampler

Another end effector means is the long rod penetrator sampler and is shown in figure 6. The penetrator tip means (24) is made from a high density material such as tungsten, preferably single crystal tungsten, or depleted uranium. This material enables the penetrator to penetrate hard substances such as nicks or other solid materials. Testing may demonstrate that more conventional materials such as super-alloys may be substituted for the tip. The entire penetrator means (28) is made from high strength super-alloys such as 4130 steel; this is to minimize buckling of the penetrator as it impacts the surface.

Figure 6. Long Rod Peneirator Sampler

There is a lower tapered bleonie boss means (25) which provides a transition from the peneirator tip means (28) to the sample pouch means (27). A sphincter means (23) provides a mechanism for closing the sample pouch means (27) once it is withdrawn so the sample isn’t lost A variety of sph incter means are feasible from a simple circumferential spring, to a tricuspid valve arrangement; up to an explosive squib to crush the tapered boss means (25) and separate the lower conic from the upper pouch container. A variety of tips can be screwed into the end effector means (26) of the peneirator means (28). The sample pouch means (27) is a flexible pouch which is securely attached to the upper removable boss means (32} and which is secured by friction to the inner opening of the upper part of the peneirator at the flared end (30). ^' Site removable boss means also provides the secure connection to the lower tether via means of six lanyards. The flexible sample pouch means (27) is designed so that the pouch can he removed even if there is some deformation or buckling of the penetrator means (28), The flared end (29) provides a means of stopping the penetrators means (28) so that the removable boss means (32) is not covered, preventing reclamation of the sample

Upper Boss: The Upper Removable Boss Means is shown in Figure 7.

Figure 7. Removable Upper Buss

The removable upper boss has several roles, it provides a means of securing the penetrator means (28) via 6 lanyards (36} to the lower winch station tether (?}. It is held in place within the penetrator means (28) by friction locks via rotating elliptical locks which are preset to a specific tension, which is many times the penetrator mass, so the penetrator will not be lost during operations, descent and impact, but many rimes less than the breaking strength of the individual lanyards (36). After the impactor has penetrated the objects surface, the lower winch means begins to retract the lower tether means, exerting tension on the lanyards, which are attached to the elliptical friction locks (35), contained within the friction lock slot (40), at the lanyard attach point (30) which is offset from the friction lock pivot pin means (37). This provides a mechanical advantage which rotates the friction lock so there is clearance between the friction lock and the side of the penetrator upper flare location. This allows the Upper boss to be removed by tether tension. The sample pouch means (27) contained structural fibers (41 ) which are embedded in the upper boss structure (33). The fibers withdraw the sample pouch from the penetrator, During withdrawal, the lower sphincter means (23) closes the open end of the pouch containing the sample, The upper opening of the pouch is sealed with a magnetic slug (34), which allows the entire sample pouch and upper boss to he handled in a zero-g or micro-g environment. Each magnetic slug (34) is marked with a unique identifier which enabl es chain of custody for ail samples. The sample pouch can contain solids, aggregates, liquids, powders, or sands.

Magnetic End Effector: The magnetic end effector is shown in Figure 8.

Figu re 8. Magnetic End Effector

The magnetic end effector has substantial terrestrial analogs, and is use in metal scrap yards as a means to separate steel from non-ferrous materials such as aluminum and copper. In this application is would be used to collect pre-positkmed samples collected by another device which are contained in their own special vault. The magnetic etui effector Is comprised of a connector means (42) which attaches to the lower winch tether, a main structure means (43), and a remotely activated electromagnet means (44). The container will he required to have a corner reflector for identification and either be made from ferrous (magnetic) material, of have a permanent magnei at lived to the outer portion of its structure so the magnetic end effector can magnetically attract it. When in vicinity of the special sample container, the electromagnet is energized, attracting and affixing the sample container. When aboard the main spacecraft, the electromagnet is tamed off, allowing the sample container to bemanipulated at will.

Penetrator Storage Vault in order to maintain chain of custody and enable multiple samples to be taken during a single mission, a penetrator vault means (45) which holding a plurality of penetrators (28) is shown in Figure 9 and Figure 10.

Figure % Penetrator Vault End View

number of axial passages (49) are formed in the shape of the penetrator means (28). At the end o f the passage (49) there exists a haul-back winch means (50). The end of the penetrator means (28) is magnetically attached to the end of a magnetic end effector attached to the haul-back winch means (50) tether. The winch reels out as the penetrator is extracted from the passage (49) as it is prepared for use. The magnetic end effector remains exposed at the end of foe passage 29) until foe- sample pouch means (27) is returned from the sample gathering scenario. When the sample pooch means (27) is returned, the end of the sample pouch is magnetically reatached to the magnetic end effector, A signal is sent from an onboard computer on the main spacecraft means (1) to reel back the sample pouch. An identification means scheme (34) on the sample pouch end to maintain inventory control. The penetrator vault may be employed on either embodiment of the tether system, or it may be employed on other applications.

Technical 1 «formation

The various tether system approaches can be used in specific conditions and both have advantages and disadvantages. The primary advan tage of the rotating tether embodiment is that most of the relative motion between the lower winch means (4) and the surface (6) if in orbit is nullified by the counter-rotational motion. However, a great deal of rotational energy is contained in the rotating system· This rotational energy must be added prior to start of actual sample gathering and subtracted after samples are gathered. However, this rotational approach is most advantageous when operating in orbit around a world which has a sensible atmosphere; this eliminates a substantial amount of drag, since the relative motion between the lower winch station, hence sample gathering system, is eliminated. In order to eliminate multiple spin-up/spin-down steps, multiple sample gathering end effectors should be taken prior to the initial spin-up of the rotating tether.

The gravity-gradient stabilized tether is the simpler of the embodiments, and there is no energy penalty for spin-up and spin-down. It is also not necessary for multiple sample gather means to be carried. The other primary advantage is that of synchromcity. The gravity gradient system can collect a sample at any arbitrary time If the sample location is along its ground-referenced orbital path. The rotating tether needs to synchronize the rotational position and geographical position so the lower winch station is at the proper location. This may require orbit modification and several orbits to accomplish.

Parameters for Mars

In Table 1, relevant parameters for tether system calculations relevant to Mars Is depicted. These data enable us to calculate specific orbital parameters. In Table 2, parameters for a gravity gradient stabilized tether system are shown, What is calculated in this table is the orbital period as a function of orbital altitude and the surface track velocity based on the orbital altitude without compensating for Mars rotational velocity and the far right column calculated the velocity relative to the surface compensating for Mars rotational velocity presuming an equatorial orbit. For the gravity gradient system to be able to capture a sample, the lower winch station must provide that right-hand column GY in order to place the sample mechanism in a stationary position. The trade-off for this system is between the length of the tether as shown in column 2 (Altitude), and the D V (column 6). It seems that a proposed tether length between 2500 and 3500 km would be ideal, since that dramatically reduces the amount of GV required. For a system using mono-methyl hydrazine and nitrogen tetroxkk- storable propellants, a total on-board OV of- 4 km/s is probably the maximum feasible, consequently, between 3 and 4 samples could be collected per fuel load depending upon system altitude,

The gravity gradient system in not restricted to equatorial orbits and inclined orbits are feasible. However, once an orbital inclination is selected, it is very difficult to modify A polar orbit allows access to the entire planet's surface, however, a slightly higher□ V is required for near equatorial sample loca tion s as the rotational velocity of the planetary surface - 240 m/s most be compensated for with on-board propulsion. Furthermore, the relative surface velocity profile from column 3 must he used as opposed to the profile from column 6 For a polar orbit, a sy stem alti tude of 4,500 km might be more ideal.

For a. rotating tether system, the orbital altitude is minimized by the available tether tip speed, which, in turn is regulated by the tether material specific strength. There are three tether strength parameters of interest The characteristic velocity Vs.· J$ the most useful and is given by;

Where U is the design stress and□ is the tether cable density. This is the no safety factor velocity and is the maximum tip speed achievable with materials of the aforementioned properties. For the two most popular tether materials, Zylon and Spectra 2000, the parameters for Vc with various safety factors is shown in Table 3.

As may be noted, for lower altitudes, the orbital velocity Is such that the specificvelocity of neither Spectra 2000, nor Zy ion is sufficient to operate without some uncompensated lateral motion. At an altitude of 1500 km* the characteristic velocity of the two materials is such that Spectra 2000 can be used with a safety factor of one (not recommended), and Zylon cannot be used. Above 1500 km, spectra and Zylon can be used. The chart also gives velocities along the surface for an inclined orbit. A positive number means the surface is going slower that the tether tip, a negative number means there is margin between the material characteristic velocity and the required velocity to match the surface translation rates. Consequently, a rotating tether needs to be above 1 ,500 km in order to require minimal use of lower winch station cut-board□ V for position-keeping.

Tether Systems Analysis

Data contained in the following pages are specific to various conditions on the planet Mars, While this is a specific example, foe equations are general and can he applied to any celestial body. Depending upon celestial object conditions, a solution may not be feasible, For example, when encountering an object such as Jupiter, strength of materials and the object \ gra vitational field may limit how far down into the Jovian atmosphere a sample collection device may be capable of reaching. This 1$ not to state that no samples can be gathered, merely that there is a physical limit to the depth into the atmosphere the sample collection device may he able to go.

Tabic 1 Relevant Mars Parameters

i able 2 (jrsvity Cinfo!eni Stabfoned I ether bystem hammerers

Table 3. Critical Velocity for &ylon and Spectra 290®

Table 4. Parameters for Rotating Tether versus Altitude and Inclination Provisional Application 62/ft31213

BACKGROUND OF THE INVENTION

I.. F ield of the I n vention.

The present mvendoft relates generally to acquisition, transport, archiving, and beneficiation of space mineral resources, Including the acquisition of samples for scientific investigations on Earth or on orbiting space stations. More specifically, the present invention employs a series of orbiting tether stations, operating in concert with very specialized end-effectors which lntegfate _: with the tether apparatus to gather samples or bulk quantities of space mineral resources in zero-g, tfaetkmal-g, or multiples of Earth gravity environments. Gathered samples can be archived, beneileiaied, or transported in bulk on the orbiting tether spacecraft which can propel itself in space any where in interplanetary' space. Alternatively, the archived or bulk samples may be transferred to another spacecraft for transport to a distant receiving station for future use, enabling the orbital tether spacecraft to continue operations.

Another use of this apparatus Is to transport hulk materials from one place on a celestial body to another without need for a surface transportation system, dramatically reducing costs to support m-situ resource utilization, and greatly enhancing the utility of a centralized processing location. Furthermore, the apparatus may he used to transport refined materials to distant locations on a celestial body where they may be utilized effectively,

2, Background

Current sample return missions are very complex affairs. Indeed the proposed Mars Sample Return Mission requires three missions and three separate spacecraft, and its proposed cost Is - · $88 in order to return ~ 300 gram of samples from a single location. The reason is that one spacecraft contains a lander, and perhaps a rover to collect and archive a sample from a single location on the celestial body. Another spacecraft is landed which contains a small rocket launcher into whose payload hay the sample is inserted. This launcher is launched to coincide roughly with the orbital position of a third spacecraft which will rendezvous and. transfer the sample container and return to Earth, This sequence of events can vary depending upon the depth of the surface gravity well from which the sample is being collected. The greater the gravity well, the smaller the sample and the greater the mission’s complexity and cost.

As a concrete example, NASA JPL’s Mars Sample Return Mission is comprised of three separate payloads. Payload 1 is the Mars Science Laboratory, which is capable of gathering a sample from a limited geographical region and places it. in a sample container. The Mars Sample Return L antler is a separate mission and contains fee Mars Ascent Vehicle into which the spherical sample container would be placed. The third mission is the Mars Sample Return Orhiter, which would rendezvous with the spherical container, retrieve it and carry it back to Earth for analysis. The mission is startlingly complex and carries high risk of failure due to fee myriad of tasks which must be 100% successful.

The concept of using a tether to capture and return samples Is not new; a very embryonic concept is described in NASA’s space tethers handbook. This concept is substantially different from the purposed invention as it requires a lander. It differs from this concept in that some form of explosive or compressed gas or spring system is required to force the peeetrator into the surface in order to collect the sample. The sample material is supposed to enter the sample through holes in the container which is then explosi vely sealed. This concept presumes a great deal about the target of the sample return with little a priori information:

4. Hardness of the body’ s surface

5. Granule size of the sample material

6. How the solid sample container is removed if the penetrafor has buckled from impact

Technically, the proposed concept provides insufficient insight as to how actually build it; however, the concept is in the open literature. Concepts described for sample returns in the open literature, or those reduced to practice operate in a gravity well so that certain transfer operations of the sample can occur under the influence of gravity, consequently, a samplecontainer "can be tilled from a sample collector under the influence of gravity. Even a very modest gravity field, such as the Moon’s with a gravitational acceleration of 16g provides sufficient force to empty or fill containers without resorting to affirmative techniques.

Added Technical Means Summary-Primary Embodiments

In the earlier disclosure, two different mechanisms for retrieving samples were discussed: a rotating and a gravity-gradient stabilized tether. The first concept Figure 1. involves a rotating momentum exchange type of tether, although the purpose of this tether is not primarily to i mpart momentum to the captured sample. In the graphic* the rotating tether is comprised of a rotating main spacecraft station means { 1) which contains all the elements of a spaceerafi. such as power, attitude control, main propulsion, energy storage, and at least one winching station to extend and retract the extensible tether cable means (3) lower winch station and the counterweight means (2). In the expanded means, the counterweight encompasses a means of propulsion, an electric propulsion means, with power processing equipment, a propellant tank means and a gimbaled thruster means. The rotating tether is placed in soite desired orbit around the celestial object from which the sample is to be taken with an orbital velocity Vo at an altitude of HR, The main station is set into rotating motion such that the product of the rotational rate times R is the orbital velocity, with a rotation vector such that when the lower winch station is nearest the celestial object’s surface, the product of the rotational rate and the tether cable length R, C0XR Is approximately equal to the orbital velocity, hut in the opposite direction to the orbital velocity·' vector at the nadir location. This yields a condition where the lower winch station means (4) is relatively unmoving with respect to the object's surface. The altitude, hence R, and the rotational rate can be modified to account for the rate of rotation of the object or planetary: surface.

Consequently . as the tether rotates, the lower tether station has an apparent motion perpendicular to the body’s surface, and can allow the release of various end effectors for collection of samples without substantial maneuvering required of the lower winch station for a short duration. Various orbital inclinations are feasible for various missions. For example, if the tether sample system is used to gather samples or to relocate vita! resources from one location on the planet to another and the locations are on or near the equator, an equatorial orbit is optimum. For prospecting for samples globally, a polar inclination is likely of greatest benefit.

There is a secondary tether means i5 ⁷ ) which operates in concert or independently of the main tether mean (3 ) The primary purpose of the secondary tether is to transport various sample gathering end effector means (described later) to the lower winch station and to transfer from the lower winch station means (4), sample pouches which contain gathered samples. This is an extremely important addition to the rotating tether. The rotating tether, with the lower winch station means (4), contains substantial angular momentum. If then system were to have to reel in the lower tether station means (4) each time a sample was gathered the on-board reaction control and stabilization propellant carried on-board the lower winch station means (4) would be rapidly depleted. Because the secondary tether means (57) is intended to operate once the primary main tether means (3) is deployed and rotating, the secondary tether means (57) must be attached by a plurality of pulley assembly means (58) distributed along the secondary tether means (57\ Figure 12, and the main tether means (3). The pulley means are affixed to the base of the main tether station means (1) and the secondary tether means cable (57) runs through a guide hole with a tensioner bolt. The pulley sheave permanently encloses the main tether means

(3). The pulley means (58) allows the secondary tether means (57) to travel freely along the main tether menus (3) as it is pulled up or dropped down to the lower winch station means

(4). The rotating tether contains substantial angular velocity, and if the secondary·· tether means (57) were not anchored to the main tether means (3) by these movable pulley means (58), the secondary tether would float around in space independent of the main tether means (3).

The lower winch station means (4) contains most elements of a spacecraft, including attitude and reaction control power, structure, and a smaller winching means to lower a secondary tether means (?) which can operate independently or in concert with (3), to which is attached one of several types of end effector means (5 ) for gathering or transporting samples.

Figure 11. Rotating Sample Tether with Lower Winch Station

The rotating tether means in this embodiment is modified from the original description in that a second lighter weight tether line means (4), a dashed line, which can be attached to the main tether line can be raised and lowered independent of the main tether line.

The secondary tether line performs an important function. The rotating lower winch station can be quite massive, given that it contains many of the features of a complete spacecraft; additionally, St contains a robotic arm for transferring sample pooches, a series of end effectors, including a plurality of a given type of end effector depending upon the desired sample capability. Depending upon the celestial object being sampled, the angular momentum and tip velocity can be quite large, if the lower wifteh station were to he winched to the main station even·· time a collected sample was to be gathered, a considerable amount propellant would be expended, detracting from the capability to obtain numerous samples. Since, due to the reduction in moment of inertia as the lower winch station is reeled in, the rotation rate becomes extremely high. Since the radius decreases to a very small level, if velocity is not shed, the tension in the tether can become extremely high. Designing a tether to accommodate this would result in an unnecessarily massive tether. Further the additional loads would require the lower winch station to possess more structural strength, increasing its mass, compounding the problem. The electric propulsion means is used to generate rotational motion in the tether system gradually as the tether is extended.

While the lower tether means contains ti propulsion system, this is designed to compensate for unintended lateral motions of the lower tether station while it is in operation, and not to rotate the tether system. Below is a table of some of the relevant parameters of a rotating tether system at the Moon and Mars,

Table 5. Orbital & Tether Parameters for Moon & Mars

The values listed In

Table s, are approximate, but completely acceptable for the conceptual analysis involved here if the lower winch station propulsion system were to be used for countering the rotational velocity a greet deal more mass would be required; the electric propulsion system is better suited for this task.

In order to alleviate the condition where the lower winch station mast be decelerated each time a sample is to be recovered at the main platform, a secondary tether line means (57), is installed and operates independent of but parallel to the main tether means (4) and is attached to the mam tether line by a plurality of pulley means (58) which are attached semipermanently to the secondary tether line means, but are free to travel up and down the main tether means with the pulleys providing low friction fracking of the main tether line. This enables the secondary tether means to be close to the main tether line in order to capture the sample, but also compensates for angular momentum differences. When a sample is to he captured, the secondary tether line end is captured by a robotic arm (), and end effectors or sample pouches transferred. The robotic manipulator aim is present on both the main spacecraft means (59), and the lower winch station means (4). The robotic manipulator arm Is capable of transferring and one of the several di fferent end effectors as described later. The entire assemblage, the desired end effector and secondary tether is lowered toward the lower winch station with the aforementioned pulleys being attached to the secondary tether line means (57) and the main tether line means (3), and the lower winch station means (4) robotic arm means (} captures the lowered end effector, or an empty line to which a sample may be winched up to the main spacecraft means ( I).

There is a plurality of pulley means (58) retained at the main spacecraft already threaded through the main tether line (3) on the pulley sheave side of the pulley means. As the secondary tether means is lowered, the manipulator arm actuates an over-center locking mechanism

In this fashion, the end effector is lowered to the lower winch station without generating motions independent of the main tether line. Note: A substantial amount of angular momentum will have to be added to the lowering end effector (although small compared to the total rotating tether system) A similar amount of angular momentum will have to be shed on the upward trip, if the secondary tether line pulleys were not in. place, the secondary tether would possess a wild motion independent of the main tether line, Secondary Tether Pulley Means

The secondary tether pulley means is shown in Figure 12 The secondary pulley means (58) is comprised ofa rigid housing means (61 ) to which is attached a secondary tether means (58) channel means (63) through which the secondary tether means passes as the secondary tether means (58) is reeled out or In. if the secondary tether means is being reeled out, the pulley means (58) will be temporarily affixed to the secondary tether means (58) by means of the tether clamping bolt means (62). The clamping bolt means may have a freely floating swivel pad at the tensioning end to minimize secondary tether means chafing. (Note: since there is very little actual force on the secondary tether, the clamping force should be quite minimal). The bolt is loose and does not grasp the secondary tether means (58) until a calculated amount of secondary tether means (57) has been reeled out. When the secondary' tether means is being reeled in or out, the pulley is permanently rim along the sheave means (64) which can freely rotate being attached to the housing means (61 ) via a low friction axle means (60), of the pulley means (58) to provide a low friction coupling of the secondary tether means (57) to the primary tether means (3). When the calculated amount of secondary tether means has been reeled out, the secondary tether means (57) is stopped, and the: end effector on the main spacecraft manipulator arm means (39), twists the clamping bolt means (62) until it soundly grasps the secondary cable means (57). This process is repeated until thesecondary cable means: has reached the lower winch station (4), When the secondary cable means (57) is being withdrawn to the main spacecraft station, the process is reverse, and the clamping bolt means (62) is loosened to allow passage of fee secondary tether means (57). In an alternative embodiment, the clamping bolt means (62) may be replaced with an elliptical friction lock to secure the pulley means (58) to the secondary tether means (57). In another embodiment the secondary' tether means (57) may employ small metal bands covering selected portions of the secondary tether means to prevent chafing of the secondary tether line when the pulley means is secured to the secondary tether means by tightening of the clamping bolt means.

Figure 12. Secondary Pulley Means (58)

Dexterous Remote Manipulator Arm Upon arriving at the lower winch Station, a dexterous manipulator arm affixed to the lower winch station means (4), grasps has already grasped the end of the lower winch station tether which it fastens to the top clasp on the end effector. The next series of steps enable transfer of the sample collector to the lower winch tether while providing substantial provision for not dropping the end effector. The dexterous manipulator amt means (), connects a temporary attachment means () to the end effector attached to the secondary tether. The temporary attachment means may be some form or earabiner, protected hook, or other positive attachment mechanism. After this temporary device is attached ί» the end effector, the manipulator arm releases the attachment connecting the. end effector means to fee secondary tether means, The manipulator arm means the transports the end effector to below the lower winch, grasps a similar attachment device attached to the lower winch tether line; once this is properly attached, the temporary holding attachment is released and the end effector attached to the lower winch tether is released.

An alternati ve embodiment of this Is for the remote manipulator arm to bring the lower winch station attachment up to the end effector which has been transported to the lower winch station, attach the lower winch tether to the end effector, release the attachment to the secondary upper tether and, using the remote manipulator, lower the end effector to below the Sower winch for operations.

Lower Winch Station

Figure 3, Lower Winch Station

The lower winch station means (4) is shown conceptually in Figure 3. The lower winch station means (4) is comprised of energy storage means (8), with a preferred embodiment of Uftuum-ion batteries, in this concept; three energy storage devices are shown, The station is comprised of an external structure means (9) which is used to mount all of the internal and externa! components and to connect the lower winch station to the extensible cable means (7). There exist radar sensor means (10) which measures lateral velocity so that the sample gathering means can be stationary with respect to the surface. There exists an imaging sensor means to image the surface or items on the surface mounted to the lower portion of the structure in order to image the desired sample location, A communications means is contained within the structure to communicate necessary information to the main spacecraft station. LOUT lateral reaction control thruster means (11) provide a method to eliminate lateral motions so the end effectors can impact the surface with only vertical motion unless lateral motion is required (e.g,, drag line end effector). A lower winch drum and motoring means (12) is used to raise and lower the end effectors which actually collect samples. The lower winching means (12) is mounted to the exterior structure means (9) with winch mounting structure means (13). A plurality of sample collecting end effectors can be mounted to the bottom of the external structure means (9) w inch can be used to collect a plurality of samples each time the lower winch station means is lowered toward the surface. In another embodiment, end effector can be lowered to the lower winch station means (4) by action of the secondary tether means (57) _: . A remote, manipulator arm means (64) is used to attach or detach the end effector means or sample pouch means from the lower tether means (7).

Dexterous Manipulator Arm

Figure 4, Dexterous Manipulator Ami

The remote dexterous manipulator an» DRMA, is depicted in Error ! Reference source not found..

The DRMA means (64) i s comprised of a plurality of parts. The DRMA means (64) is attached to the lower winch station means (4) by a mounting pad, which contains a stepper drive motor means (65) use to rotate the DRMA means to precise locations. The DRMA means contains a plurality of arm means (67) which are dri ven hy stepper motor means (68) which can rotate the arms means pv7) in two orthogonal directions to accurately position the end effector head means (70), A special stepper motor means contains a uni-axial stepper motor means (69) to accurately position the precision end effector means (70) using a linear actuator, A second stepper motor means is used to accurately rotate the end effector means (70) to accurately position the end effector. This end effector is primarily used to attach and detach attachment means (an example of which is a carablner means {) and move the sample pouch means or the new end effector means from the secondary tether means (57) to the lower tether means (7).

Operations

The lower winching station (4) is released from the main spacecraft tether station means ( I }. For the rotating tether means the winching station means is extended as the entire system is “spun-up” to its desired rotational velocity. For the gravity-gradient stabilized means, the extensible tether means (3) is simply lowered toward the surface until the desired height above the surface is attained.

In the rotating tether means, the lower winching station begins collection operations when the station is within -AKF of actual nadir. The sensors aboard the lower winch station locate the desired sample location and the on-hoard processor means calculates when to release the braking mechanism on the lower winch means so the sample collecting end effector impacts the desired location.

The gravity gradient stabilized means requires the lower winch station to engage the reaction control thrusters to move the lower winch station forward along the path traced along the ground, and once the desired distance has been achieved, the thrusting is managed to hold the lower winch station in a stationary position, the sample end effector is released, the sample gathered, and the collector is recovered. Sample end effectors from the plurality of those mounted on the exterior structure may be replaced to gather a plurality of samples.

End Effectors

Clamshell Excavator: The clamshell excavator is shown in Figure 4. The clamshell excavator is designed to collect bulk samples in either a gravity or 0-g/miero-g environment.

Figure 13. Clamshell Excavator

The clamshell excavator operates in much the Same fashion as terrestrial Olamshel! excavator does with key modifications to enable operations in zero or micro- gravity environments.

The clamshell excavator means (Figure 4} is comprised of a connection means (14) to connect the clamshell excavator means to the lower winch cable means (?). The clamshell bucket is forcibly opened and closed by a pair of electromechanical actuators ( 15), The clamshell bucket is comprised of a pair Of section means (17) which contain a flexible liner means (18) (shown later), Clamshell Liner; The clamshell liner means is a flexible liner designed to contain collected samples in a realistically leak-resistant, flexible container as shown in Figure 5.

Figure 6. Clamshell Liner

The clamshell liner means (19) is made from an impervious semi- flexible material or fabric which is conformal to the inner geometry of the metallic clamshell bucket means. The upper portion of the liner contains magnetic attachments to hold the liner in place at the top portion of the bucket sections. The liner has a pivot point means at {21 ), The liner has a toothed or smooth magnetic leading edge means (22), which holds the liner In place at the bucket jaw leading edges, and when the bucket is dosed with the sample inside, the magnetic leading edge seals the container closed and traps the sample inside without releasing the contained sample material. When the bucket is opened, the sealed container can be removed and place in storage with some mechanical device and stored as required.

Long Mod Peaetrator Sampler

Another end effector means is the long rod penetrator sampler and is shown in Figure 6. The penetrator tip means (24) is made from a .high density material Such a$: tungsten, preferably single crystal tungsten, or depleted uranium. This material enables the penetrator to penetrate hard substances such as rocks or other solid materials. Testing may demonstrate that more conventions! materials such as super-alloys may be substituted for the tip, The entire penetraior means (28) is made from high strength super-alloys such as 4130 steel; this is tominimize buckling of the penetraior as it impacts the surface.

Figure 7. Long Rod Fenetrator Sampler

There is a lower tapered biconic boss means (25) which provides a transition from the penetrator tip means (28) to the sample pouch means (27), A sphincter means (23) provides a mechanism for closing (he sample pouch means (27) once it is withdrawn so the sample isn’t lost, A variety of sphincter means are feasible from a simple circumferential spring, to a tricuspid valve arrangement up to an explosive squib to crush the tapered boss means (25) and separate the lower conic from the upper pouch container A variety of tips can be screwed into the end effector means (26) of the penetrator means (28). The sample pouch means (27) is a flexible pouch which is securely attached to the upper removable boss means (32) and which is secured by friction to the inner opening of the upper part of the penetrator at the flared end (30), The removable boss means also provides the secure connection to the lower tether via means of six lanyards. The flexible sample pouch means (27) is designed so that the pouch can be removed even if there is some deformation or buckling of the penetrator means (28), The flared end (29) provi des a means of stopping the penetrators means (28) so that the removable boss means (32) is not covered, preventing reclamation of the sample pouch.

Upper Boss: The Upper Removable Boss Means is shown in Figure 7

figure 8, Removable Upper Boss

The removable upper boss has several roles, it provides a means of securing the penetrator means (28) via 6 lanyards i 3t>) to the lower winch station tether (7). It is held in place within the penetrator means (28) by friction locks via rotating elliptical locks which are- preset to a speciik tension, which is many times tire penetrator mass, so the penetrator will not be lost during operations* descent and impact, but many times less than the breaking strength of the individual lanyards (36), After the impact»? has penetrated the objects surface, the lower winch means begins to retract the lower tether means, exerting tension on the lanyards, which are attached to the elliptical friction locks (35), contained within the friction lock slot (40), at the lanyard attach point (3ft) which is offset from the friction lock pivot pin means (37), This provides a mechanical advantage which rotates the friction lock so there is clearance between the fri ction lock and the side of the penetrator upper flare location. This allows the upper boss to be removed by tether tension. The sample pouch means (27) contained structural fibers (41 ) which are embedded in the tipper boss structure (33). The fibers withdraw the sample poach from the penetrator. During withdrawal, the lower sphincter means (23) doses the open end of the pouch containing the sample. The upper opening of the pouch is sealed with a magnetic slug (34), which allows the entire sample pouch and upper boss to be handled in a zero-g or micro-g environment. _: Bach magnetic slug (34) is marked with a unique identifier which enables chain of custody for all samples. The sample pouch can contain solids, aggregates, liquids, powders, or sands.

Magnetic End Effector: The magnetic end effector is shown in Figure 8,

Figure 9. Magnetic End Effector

The magnetic end effector has substantial terrestrial analogs, and Is use in metal scrap yards as a means to separate steel from non- ferrous materials such as aluminum and copper. In this application is would be used to collect pre-positloned samples collected by another device which are contained in their own special vault The magnetic end effector is com prised of a. connector means (42) Which attaches to the lower winch tether, a main structure means (43), and a remotely activated electromagnet means (44). The container will be required to have a corner reflector for identification and cither be made from ferrous (magnetic) material, of have a permanent magnet affixed to the outer portion of its structure so the magnetic end effector can magnetically attract it. When in vicinity of the special sample container, the electromagnet is energized, attracting and affixing the sample container. When aboard the main spacecraft, the electromagnet is turned off, allowing the sample container to be manipulated at will,

Penetrator Storage V atilt in order to mai ntain chain of custody and enable multiple samples to be taken during a single mission, a penetrator vault means (45) which holding a plurality ofpenetrators (28) is shown in Figure 9 and Figure 10

Figure 10. Penetrator Vault End View

The penetrator vault means (45, 48) is formed using a strong lightweight and not?- contaminating material. A number of axial passages (49) are formed in the shape of the penetrator means (2S), At the end of the passage (49) there exists a haul-back winch means (SO). The end of the penetrator means (28) is magnetically attached to the end of a magnetic end effector attached to the haul-back winch means (50) tether. The winch reels out as the penetrator is extracted from the passage (49) as it is prepared for use. The magnetic end effector remains exposed at the end of the passage 29) until the sample pouch means (27) is returned from the sample gathering scenario. When the sample pouch means (2?) is returned, the end of the sample pouch is magnetically reattached to the magnetic end effector. A signal is sent from an on-hoard computer on the main spacecraft means (1 ) to reel back the sample pouch. An identification means scheme (34) on the sample pouch end to maintain inventory control. The penetrator vault may be employed on either embodiment of the tether system, or it may he employed on other applications.

Figure 11, Penetrator Vault Side View Tether Line Brag Excavator

The tether S ine drag excavator is a modification of a terrestrial drag line excavator bucket to operate in fraction or even, multiple gravity levels on different celestial bodies. Similar to the terrestrial drag line excavator which can be used for removing overburden in mines or for clearing channels or other dredging operations, the tether line excavator bucket is an end effector which can be used to transport bulk .material from one site to another. In this regard, it is simpler than the clamshell bucket excavator, and should be more amenable to bulk material excavation and transport A notional drawing is shown in 1 1

Figure 12. Tether Line Drag Excavator

The tether drag bucket means is comprised of a forward mounting ring (53), which is permanently affixed to a moveable (in rotation) forward hit if ame (52). The forward lift frame (52) is attached to one of a plurality of tether lines from the lower tether station means (4). The other tether line means atach to the rear mounting _· ring means (54) to provide support to the bucket when it is lifted from the surface of the celestial object. There may he a plurality of rear attachment rings (54) for operational stability and support. These are all attached to the tether line excavator body primary structure means (56), which provides structural integrity to the entire device. At the front (open end) of the drag bucket, are a setof teeth means (55) for aiding in excavating packed surface material and aid in filling the bucket.

Operation of the tether line drag bucket is entirely different from its terrestrial counterpart. In terrestrial operations, a large crane affair is used to drop the drag bucket to the surface;

another cable attached to the forward feme is operated in tension, dragging the bucket, allowing the teeth means (55) to dig into the earth, filling the bucket. Lifting tension is then applied to the front and rear mount ring means (53* 54), and the bucket is Sifted, When it is to be emptied, tension is applied to the rear mount ring means, tilting the bucket forward and emptying it of its contents.

When attached to either the rotating or gravity gradient tether, the tether line drag excavator means (52-56) is caused to achieve some: velocity relative to the surface of the celestial object (notionaliy 50- 100 m/s). The forward tether means connected to the forward mounting ring (53) provides continuous tension to keep the forward end of the bucket aligned with the velocity vector to ensure the bucket is filled properly, In an alternative embodiment, a set of momentum gyro means may need to be employed to retain the proper bucket orientation prior to the excavation operation. When the bucket strikes _. the celestial object's surface* the forward momentum of the bucket provides the necessary force to (ill the bucket. This is a new embodiment of the classical drag bucket.

Sample Transfer System

The sample transfer system means (73) is comprised of two major components, the sample package spacecraft and .reentry shield means (82) and the transfer vehicle means (81), This system is based on US patent 1JS628678? which is Incorporated here in its entirety by reference. It is noted that the aforementioned patent covers _: transfers from Geosynchronous Orbit to Low Earth Orbit. The concept is herewith expanded to include orbits beyond GEO to LEO and to locations in lunar orbit and other locations in our solar system. The transfer vehicle means (81) is comprised of avionics and propulsion to be able to change primary orbits of the entire spacecraft sample return means (73) from the sample location to the Earth.

Figure 14. Sample Return System

The Sample package spacecraft and reentry shield means (82) is comprised of transfer vehicle sample container adapter ring means (74), a sample container means (75), which, without loss of generality may be the storage vault means (45), The sample container means (76), which contains the avionics suite means (78), is inserted into the Sample Spacecraft means (82). The sample spacecraft means (82) contains propulsive means, including attitude and roll control means (77), Considerable propulsive energy is saved by a reentry shield means (79) skipping in and out of the Earth’s atmosphere, bleeding off energy and lowering the spacecraft's orbit prior to rendezvous with another spacecraft, such as the International Space Station (1 SS).

technical 1 «formation

The various tether system approaches can be used in specific conditions and both have advantages and disadvantages The primary advantage of the rotating tether embodiment is that most of the relative motion between the lower winch means (4) and the surface (6) if in orbit Is nullified by the counter-rotational motion. However, a great deal of rotational energy is contained in the rotating system. This rotational energy must he added prior to start of actual sample gathering and subtracted alter samples are gathered. However, this rotational approach is most advantageous when operating in orbit around a world which has a sensible atmosphere; this eliminates a substantial amount of drag, since the relative motion between the lower winch station, hence sample gathering system is eliminated. In order to eliminate multiple spin-up/spin-down steps, multiple sample gathering end effectors should be taken prior to the initial spin-up of the rotating tether.

The gravi ty-gradient stabilized tether is the simpler of the embodiments, and there is no energy penalty for spin-up and spin-down. It is also not necessary for multiple sample gather means to he carried. The other primary advantage is that of synchronictty. The gravity gradient system can collect a sample at any arbitrary time if the sample location is along its ground-referenced orbital path. The rotating tether needs to synchronize the rotational position and geographical position so the lower winch station Is at the proper location. This may require orbit modification and several orbits to accomplish.

Parameters for Mars

In Table 1 , relevant parameters for tether system calculations relevant to Mars is depicted. These data enable us to calculate specific orbital parameters. In Table 2, parameters for a gravity gradient stabilized tether system are shown. What Is calculated in this table is the orbital period as a function of orbital altitude, and the surface track velocity based on the orbital altitude without compensating for Mars rotational velocity and the far right column calculated the velocity relative to the surface compensating for Mars rotational velocity presuming an equatorial orbit. For the gravity gradient system to he able to capture a sample, the lower winch station must provide that right-hand column OV in order to place the sample mechanism in a stationary position. The trade-off for this system is between the length of the tether as shown in column 2 (Altitude), and the AV (column 6). it: seems that a proposed tether length between 2500 and 3500 km would be ideal, since that dramatically reduces the amount of AV required. For a system using mono-methyl hydrazine and nitrogen tetroxide storable propellants, a total on-board AV of -- 4 km's is probably the maximum feasible, consequently, between 3 and 4 samples could be collected per fuel load depending upon system altitude.

The gravity gradient system in not restricted to equatorial orbits and inclined orbits are feasible. However, once an orbital inclination is selected, it is very difficult to modify. A polar orbit allows access to the entire planet's surface, however, a slightly higher AV is required for near equatorial sample locations as the rotational velocity of the planetary surface - 240 m/s must be compensated for with on-board propulsion. Furthermore, the relative surface velocity profile from column 5 must be used as opposed to the profile from column 6, For a polar orbit, a system altitude of 4,500 km might he more ideal

The gravity gradient system in not restricted to equatorial orbits and inclined orbits are feasible. However, once: an orbital inclination is selected _» it is very difficult to modify. A polar orbit allows access to the entire planet’s surface, however, a slightly higher AV is required for near equatorial sample locations as: the rotational velocity of the planetary surface ~ 240 m/s most be compensated for with on-board propulsion, Furthermore, the relative surface vcloc i ty pro file from column 5 must he used as opposed to the profile from column 6, For a polar orbit, a system altitude of 4,500 km might be more ideal

For a rotating tether system, the orbital altitude is minimized by the available tether tip speed, which, in turn is regulated by the tether material specific strength, There are three tether strength parameters of interest The characteristic velocity Ve , is the most useful and Is given by:

Where t) is the design stress and□ is the tether cable density. This is the no safety factor velocity and Is the maximum tip speed achievable with materials of the aforementioned properties. For the two most popular tether materials, Zylon and Spectra 2000, the parameters for Vi- with various safety factors is shown in Table 3

As may be noted, for lower altitudes, the orbital velocity is such that the specific velocity of neither Spectra 2000, nor Zylon is sufficient to operate without some uncompensated lateral motion. At an altitude of i 500 km, the characteristic velocity of the two materials is such that Spectra 2000 can be used with a safety factor of one (not recommended), and: Zylon cannot be used. Above 1500 km, spectra and Zylon can be used. The chart also gives velocities along the surface for an inclined orbit. A positive number means the surface is going slower that the tether tip, a negative number means there is margin between the material charaeteristie velocity and the required velocity to match the surface translation rates. Consequently, a rotating tether needs to be above 1 ,500 km in order to require minimal use «Hower winch station on-board AV for position-keeping; Tether Systems -Analysis

Data contained in the following pages are specific to various conditions on die planet Mars. While this is a specific example, the equations are general and can be applied to any celestial body. Depending upon celestial object conditions, a solution may not be feasible, For example, when encountering an object such as Jupiter, strength of materials and the object's gra vitational field may limit how far down into the Jovian atmosphere a sample collection device may be capable of reaching. This is not to state that no samples can be gathered, merely that there is a physical limit to the depth into the atmosphere the sample collection device may be able to go.

Table 6 Relevant Mars Parameters

Table 7. Gravity Gradient Stabilized Tether System Parameters

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSI VE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

I . A tether-based space system comprised of a rotating or gravity-gradient stabilized space tether platform with a lower two-axis stabilized platform and a series of end effectors, capable of operating in zero-g Ifaetiona!-g or multiple gravity regimes, the combination o f w hich enables gathering samples or bulk materials from th e surface of a celestial body without the requirement to land on the surface of said celestial body;

A spacecraft bus providing propulsion, stabilization, power, communications, sensors, equipment storage and management and control;

A long tether filament wound onto a winch capable of translating toward or away from said spacecraft bus operated with power from said spacecraft bus;

A lower winch station connected to the spacecraft bus of l, via a filamentary tether;

Said lower winch station contains, stabilization, power, communications, sensors, and control to provide two-axis stabilization and contains a secondary winch with a filamentary tether connected to any of a plurality of end effectors as claimed in 1 ,