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Project Overview - Hubble Telescope Autonomous Rescue Vehicle (HTARV)

Introduction

This document outlines a proposed capability and mission to rendezvous and dock withthe Hubble Space Telescope (HST) and thereafter safely and cost effectively extend itsoperational life. A Hubble Telescope Autonomous Rescue Vehicle (HTARV), derivedand assembled from a number of existing orbital vehicle systems will be used to transportHST to the International Space Station (ISS) for servicing. Subsequently the HTARVwill further boost HST to a higher operational orbit. This mission concept is compelledby widespread public desire to operationally sustain the greatest deep space telescope forthe continued advancement of science and public benefit. Over the past 14 years HST hasproduced untold scientific benefit and understanding of the cosmos, as well as the mostextraordinary images of the universe ever captured by humankind.

Figure 1: Recent Hubble Image of the Black Eye Galaxy

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HTARV Project & Mission Team

The following companies and government activities have formed a team to respond toNASA’s Hubble Space Telescope Rescue RFI. These entities and their prospective rolesare:

• SkyCorp, Incorporated (Huntsville, AL)o Program Team Leadero HTARV System Designo Hall Thruster System Optimizationo Flight Computer and Navigation System

• Orbital Recovery Corporation (Washington, DC)o Commercial licensee for DLR Intellectual Property TRL level 7 for

robotics, rendezvous and dockingo Commercial link to ESAo Ariane V Contract

• NASA Langley Space Center (Langley, VA)o Systems Engineeringo Space Truss Intellectual Propertyo On orbit construction expertise

• NASA Johnson Spaceflight Center (Houston, TX)o Robonautso EVA Systems

• NASA Goddard Spaceflight Center (Greenbelt, MD)o Hubble Systemso Hubble Servicing

• Pratt & Whitneyo Hall Thruster Propulsion System

• HawkEye Systems (Alexandria, VA)o EVA Experienceo EVA Planningo On orbit construction architecture planning

• Alliance Space Systems (Pasadena, CA)o Space Robotics (built the Mars rover robotic arms)o System design, structures, thermal simulation

• Boeing Satellite Systems (El Segundo, CA)• Boeing 702 Solar arrays

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SkyCorp will lead a study to:

1. Evaluate and critique the suitability of either an electric propulsive basedrescue of HST while detailing contingency plans that move HST to a 100-yearorbit.

2. Work with NASA to develop a credible scenario enabling HST refurbishmentat or in the proximity of ISS

3. Develop a high fidelity cost and mission timeline leading which captures,refurbishes and releases the HST

SkyCorp specifically proposes that NASA funds a six month long intensive design anddevelopment effort in cooperation with our other team members as well as partnershipwith Goddard Space Flight Center Hubble servicing team. This is a serious effort andrequires serious commitment from NASA for this to be successful. Our team requests$3M from the agency to fund this effort. This would be a fixed price contract. SkyCorphas the financial wherewithal to fund this effort in a normal contract environment ofpayment on 30-day increments or less. SkyCorp is a member of the DoD CentralContractor Registry (CCR) database and has all export licenses needed to work withOrbital Recovery Corporation. Any additions can be handled through amendments toexisting Technical Assistance Agreements.

Request for Information Background

As a result of recent budget announcements, NASA has come under significant publicpressure and political interest in response to the decision to cease HST support. A seniorNASA official recently remarked: “You know we cancelled the Space Shuttle, the SpaceStation, and Hubble programs- guess which one everyone is up in arms about?” In thepast six months, two companies, SkyCorp Incorporated and Orbital RecoveryCorporation, have met with NASA officials regarding Hubble. The purpose of thesecontacts has been to brief the Agency on viable options that may be available to continueHubble operations, at considerably less expense to the federal budget.

The principal reason for cancellation of the SM4 HST mission is due to therecommendation of the Columbia Accident Investigation Board (CAIB) to conduct SpaceShuttle missions only when the capability exists to move the Orbiter to ISS “safe” haven,or after an on-orbit Orbiter Thermal Protection System (TPS) repair capability has beenproven. This decision opens the door for creative ways to salvage Hubble from de-orbitand certain destruction. This document proposes a solution that does not depend on useof Shuttle Orbiters. When established in the same orbit as ISS, and moved to a positionin close proximity to ISS, NASA HST could be readily serviced before subsequentrelocation to a higher operating orbit. Proposed to accomplish the HST repositioningmaneuvers is a multi-purpose, multi-use HTARV tug. The HTARV will be used to saveHST, support ISS logistics, and contribute to the Administration’s new Space Initiative.

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Overview of Orbital Recovery’s On Orbit Servicing Business

Orbital Recovery Corporation (ORC) is actively developing an on-orbit system that isdesigned for servicing of currently orbiting and planned GEO communicationsspacecraft. “ConeXpress” Orbital Recovery System (ORS) is a robotic system that isdesigned for either autonomous or tele-directed operations.

Figure 2: ConeXpress Orbital Recovery System (ORS)

ORC and its prime contractor, Dutch Space, are completing final design and proceedinginto the production of the ConeXpress ORS. The European Space Agency (ESA) isparticipating in development of the ORS and is providing matching funds under theauthority of its Public/Private Partnership program. ORC has recently signed a contractwith the DLR (German Space Agency) to license the use of its robotics capabilities andRendezvous-and-Capture software for use in the ConeXpress ORS. Other advancedrendezvous hardware (cameras and a communication system), to be provided by aJapanese firm, Astro Research Corporation, will be incorporated into the system. DLR,whose robotic experience began in 1983 with the Spacelab D2 mission, has substantialexperience with on orbit servicing systems and tele-operation.

DLR built a robot (that flew on the larger spacecraft and the GETEX experiment) whichexamined the dynamics of how a robotic arm influenced the overall stability of a coupledpair of spacecraft. DLR and its industrial partner Kayser Threde are currently workingclosely with ORC in development of the ConeXpress ORS. Figure 3 is a rendering of thejoint DLR/NASDA ETSVII (GETEX) mission in 1998.

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The current configuration of the ConeXpress ORS is not capable of performing theHubble Rescue mission because of its limited size, power, and thruster performance.However, a significant portion of the technology that is incorporated into the system isdirectly applicable to an upgraded ORS that is designed to in response to therequirements for a Hubble rescue mission. In particular, a number of DLR’s advancedrobotics capabilities, its onboard spacecraft navigation computer (proven on SMART-1),and its rendezvous and docking simulation system are directly usable for this application.

Figure 3: ETS VII Joint DLR/NASDA Cooperative On Orbit System

Also, DLR is in the midst of advanced development of a mission known as TECSAS thatwill be flown in a joint venture with the Russian Space Agency. DLR will launch andoperate an advanced robot on the mission that is designed to grapple a companionspacecraft. Among other objectives, DLR will gain invaluable data and experience inunderstanding the dynamics of a coupled pair of orbiting spacecraft. Within the next 18months, and preceding the TECSAS mission, a test version of this system will bedelivered to ISS to prove out operation of the robotic joints. This system will be mountedon the outside of the Russian Zvezda module and undergo a set of activities that areplanned to accurately characterize operation of DLR’s robotic arm joints in the actualmission operating environment. Successful achievement of the planned objectives willelevate maturity of this system from its current Technology Readiness Level (TRL) 5 toTRL 7. The subsequent TECSAS mission will further this maturing process anddemonstrate system TRL 8. Figure 4 is a rendering of this system.

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Figure 4: DLR’s TECSAS Mission

Of key importance to the Hubble rescue mission, an Americanized “heavy” version of theoriginal Spacecraft Life Extension System (SLES), developed by ORC, could be readilyadapted for use in the HST rescue mission.

SLES Heavy (HTARV) To the Rescue

At the outset of the Orbital Recovery System development process, SkyCorp workeddirectly with ORC to develop the SLES for GEO ComSat lifetime extension missions.The SLES design can be readily scaled up in capability in order to perform rescuemissions of stranded GEO ComSats. The design was baselined to be capable of“rescuing” ComSats of up to 5000-Kg mass. Conceptually, the SLES is designed torendezvous with ComSats located in intermediate LEO orbits of any inclination or GTOorbits, and move them to GEO. Mission operations such as these would likely requireaddition of velocity increments ( V’s) that are on the same order of magnitude as aHubble rescue mission would require. Figure 5 is an illustration of the SLES as it isenvisioned for the Hubble rescue mission.

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Figure 5: SLES Docked to Hubble at the ISS Orbital Plane

The SLES version shown in Figure 4 is the baseline “lightweight” version. The Vrequired to move Hubble from its present orbit at 28.5 degrees to the ISS orbit of 51.6degrees is approximately 3.4 km/sec (at 90% thrust efficiency). Theoretically, a 10kilowatt SLES (0.5 Newtons thrust) could accomplish this task, but it would require avery long time, measured in multiple years, to complete the transfer. Therefore a morepowerful version of the SLES, henceforth referred to as the HTARV, is needed toperform and complete the mission within an acceptable time period, generally envisionedas one year or sooner.

Preliminary calculations indicate that to move the system within a year long mission, asystem that delivers at least 2 Newtons and possibly as much as 5.6 Newtons of thrust isrequired. This is currently achievable, but the power required to do so is between 44 and88 kilowatts. Current solar array technology would require over 250 m2 of solar array forthe 88 KW worst case power demand. This is a very sizeable solar array, which wouldquite likely be difficult to fabricate and assemble, verify, and launch, if confined to aDelta IV class vehicle. Proposes is the use of two to four pairs of solar arrays adaptedfrom Boeing’s “702 Series” GEO ComSat. A single Boeing 702 solar array delivers peakperformance of 22KW, thus two to four sets would provide the 44 to 88 KW BOL powerrequirement. The 702 solar arrays are currently operating successfully on orbit in ComSatapplications, and therefore are at TRL 9. It is planned to scale up these flight elements bya factor of 4 worst case to meet the projected mission requirements.

Planned deorbit of the HST bounds the timeframe that is available to complete systemscaleup and any proof of concept requirements. Success of this approach will depend onthe ability to minimize new development. For this proposed mission to be successful, it isanticipated that Hubble would need to be retrieved before it descends below an altitude of~ 250Km, wherein after increased atmospheric drag would begin to severely hampereffective control of the HTARV system. Retrieval above this altitude could be

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accomplished with the proposed HTARV system even if Hubble were to lose effectivebenefit of its gyros due to gravity gradient induced spacecraft orientation.

SkyCorp and its team have a proposed design solution for a Hubble rescue tug (HTARV).While obligating a very innovative system design approach, all technologies required toaccomplish this mission are well within c what is commonly recognized as the currentstate of the art and meet or exceed NASA’s HST Rescue Mission RFI requirements ofTRL 5 or greater. A companion file to this RFI response, (HLESweights.xls) provides apreliminary weight budget for the system, including provision for the required Xenon wetmass. The referenced file also catalogs the assessed TRL levels of each of the HTARVsubsystem elements. A second included file (HSTrescue.ppt) d provides detailed missionimplementation data associated with the performance of the propulsion system andmission flight profile timelines.

Proposed Spacecraft and Mission Architecture

Design Options for HTARV Tug

To relocate HST from its current orbit of 593-Km altitude at 28.5 degrees to an orbit of340 Km at 51.6 degrees requires a propulsion system of considerable capability andcapacity. Hubble weighs in excess of 11,000 Kg, which requires system performance thatlies well outside the capability of any currently available propulsion system. Tounderscore this point, Centaur, the most energetic upper stage currently available fortransfer of ComSats to GEO is able to transport a 5,000 + / - Kg spacecraft. This requiresonly 1.5 Km/sec of V. Application of an equivalent amount of energy would result inonly 0.7+ / - Km/Sec of V, or only about 15% to 20% of the total energy required tomove HST to the orbital plane of ISS. Inasmuch as Centaur also performs a plane changefrom 28.5 degrees to 0 degrees (albeit at a GEO altitude where energy demands are muchreduced), there is comparatively even more performance contained in Centaur. It shouldbe possible, then, to increase the scale of a Centaur Tug to perform most, if not all of therequired transfer mission. This HST Centaur Tug would be a stretched version whosesubstantially increased fuel volume would consume the entirety of a Delta IV-H payloadbay. However, HST’s deployed solar arrays impose a mission operating constraint thatprecludes use of a larger scale Centaur. Acceleration loads imposed on HST wouldrequire retraction and redeployment of its solar arrays, considered to be an untenable riskfactor, and moreover, Hubble housekeeping functions require that power must becontinuously applied to the spacecraft. Even if capable of retraction and redeployment,HST would founder. A corollary challenge would be excessive boiloff losses of cryopropellant that would severely limit the time available to rendezvous, dock, and moveHST to the ISS inclination.

An unrelated (to HST rescue), but long-term disadvantage of a Centaur based systemwould be that it has no capability for reuse for Lunar transfer missions without acompanion capability to replenish both LOX and liquid Hydrogen while on orbit. Thiscapability is strongly needed in support of the Administration’s Space / LunarExploration Initiative but would require considerable additional near term development.

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A Xenon ion propulsion system would require only the replacement of the Xenon tanks, afar less hazardous and cost effective refueling capability with more long term potentialfor heavy payloads of a non time critical nature.

Electric Propulsion System Option

In first order terms, Electric Propulsion (EP) appears, to offer a solution that is achievableand presents the least degree of consequential risk to the telescope itself. One detrimentassociated with EP is the significantly increased transit time between the two orbits. Indiscussing electricthrusters a differentiation must be made between a grided ion system such as was usedfor the Deep Space 1 mission and Hall Effect thrusters that were originally developed inthe former Soviet Union. Response to NASA’s RFI does not warrant an extensivediscourse on the relative merits of Hall thrusters versus Grided Ion thrusters. However, itis plainly evident that the Hall thrusters provide significantly greater thrust, albeit at alower Isp than grided ion thrusters. Hall thrusters deliver Isp that is 4 to 6 times greaterthan that of chemical propulsion systems therefore requiring much less propellant thanfor a chemical system for the Hubble rescue mission. However, it has been the combinedexperiences of both SkyCorp and ORC experience in prior design circumstances thatgrided ion thrusters with high Isp and very low thrust simply do not provide sufficientperformance to move spacecraft around in LEO orbits within any reasonable time period.

Figure 6: Pratt & Whitney Electric Propulsion Systems

The specific thruster that will enable this mission possible Pratt & Whitney’s T-220HT,which is in currently in advanced development today at a demonstrated TRL of 5 shownin figure 6. This thruster delivers Isp of 1875 seconds at a thrust of approximately 1.42Newtons while consuming 22 KW of input power at an output from the power processorof 300 volts. For each solar array, two T-220HT thrusters would be clustered for

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redundant operation. This configuration would easily provide the thrust that is necessaryto move a HST class spacecraft to its new orbit. The voltage applied to the Hall thrustercould be reduced in order to minimize fuel consumption, at the expense of increasedtransit timelines. Optimization of this tradeoff is to be further studied as part of theproposed effort.

Power System

The propulsion system is not the critical path system for this development. The mostchallenging aspect to the spacecraft is the power system, including the solar arrays, arraypointing, and power interface to the T-220HT thrusters. An important starting point thatwould simplify the system would be to adopt the Boeing 702 22 KW BOL solar arrays,array pointing system, rotary joints, and power preprocessor. It would take 2 to 4 fullsets of solar arrays, which is within Boeing’s (SpectraLab) production capabilities,especially in the current market for commercial ComSats. Since the HTARV would notbe leaving LEO in order to perform the Hubble mission there is little concern relative tosolar array degradation with the use of the proposed solar panels.

A very robust and failure tolerant system could be accomplished through implementationof an electric propulsion system design that is analogous to NASA’s Saturn 1 launchvehicle. In this adaptation, each pair of EP engines would be paired with discrete andindependent solar array and power processing systems connected to the clustered pair ofT-220HT thrusters. This would avoid reliability problems associated with theaggregation of 44-88 kilowatts of power into a single power system and subsequentswitching and distribution of power into separate thrusters. A byproduct of this would bethat each solar array-power processor-thruster pair has its own built in redundancy. Thistreatment would introduce approximately 200-Kg weight penalty, but would appreciablyincrease system reliability. The mass penalty is minimal in a total system (includingHST) whose projected mass is on the order of 17,000 Kg. Some cross strapping wouldbe required so that a failure of a thruster group would not eliminate the ability to use thefuel tanks from that thruster group on the remaining thrusters.

System Architecture Using On Orbit Assembly

Another factor for a solar electric tug is the difficulty to assemble it as a single entity thatcan be integrated on a launch vehicle, deployed, and operate reliably. This is notimpossible and should be studied with equal consideration to any other approach.However, such a system lends itself to an on-orbit assembly approach whereby thesystem is assembled at ISS by crew and robots, solar arrays deployed, sent to Hubble,wherein it rendezvous, retrieves and returns to ISS. While the total V is increased, themuch lower mass on the trip to Hubble dramatically reduces total impulse needed(18,706,000 N-sec there vs. 47,741,000 N-sec on the return).

On orbit assembly of this system would enable a much lighter weight structure, a morereliable deployment of the solar arrays and thruster booms, and an opportunity to pretestbefore release. It also lends itself to a modular system implementation, robust

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redundancy, and designed in later reuse capabilities. Also, an on orbit assembled systemwould not have to qualify for the full dynamic environment or the volumetric limitationsof existing launch systems due to the use of SkyCorp’s patented vibration reductionpackaging for protecting subsystem components for launch.

With the total cost of this system is constrained by choice to no greater than that budgetedfor de-orbit of Hubble, HTARV system requirements, costs and resultant schedules couldbe very tightly controlled while also producing a system that has multiple uses beyondthe Hubble mission.

Because the Administration’s policy is to reserve use of the remaining Space Shuttleorbiter fleet as much as possible for ISS completion, reliance on it should be held to aminimum for this mission. A preliminary concept would be that the HTARVcomponents be sent up in a European ATV or Russian Progress vehicle specificallypurchased for this mission. An alternative system such as the Kistler K1 or the futureSpaceX Falcon V could be used as well for this purpose, however, viability of bothwould need to be vigorously assessed. It may be that as a minimum, the solar arrayscould be flown on a logistics mission where the Shuttle carries the MPLM. In this casethe Lightweight MPESS Carrier (LMC) that flies in the rear bay of the Shuttle would beused. It normally does not count fully against payload weight due to its role replacingballast mass for Shuttle CG optimization. These alternatives would have to be seriouslyaddressed in the context of the Shuttle’s role in completing the construction of ISS beforeits retirement.

The crew for the assembly process would be transported to ISS in a Soyuz vehicle that iscommercially purchased for this specific purpose. Discussions with Energia indicate thatwith an 18-month lead-time, this is very achievable. Both American and Russianrobotics assets on ISS would be used to support the mission. All three Soyuz crewpersons would be tasked to work on this project, with two of them being American andone Russian. The crew would stay for up to two weeks and execute EVA’s to assemblethe HTARV. Extra resources to support this crew would be taken up in the cargo carrier.

This assembly process would involve the human participants to set up the worksite, andthereafter robots such as the NASA Robonauts used to assemble truss elements for thespacecraft, deploy the solar arrays, and test the system. The worksite would be set upwith at least one NASA Langley Space Crane, the existing ISS robotics systems, as wellas any other robotic assistants needed. The crew persons would either assist theRobonauts or be there in case of some difficulty. This would help to maximize crewsafety and help to further develop these techniques for the assembly of future lunarmission components. This would be further developed during the study phase. NASALangley has extensive experience in this area and has agreed to be a team member.NASA JSC would be a team member to bring their experience with the Robonauts intothe process. Figure 6 shows two of the Robonauts assembling Langley truss elements.

A very valuable aspect to this system architecture is that at operational validation can beaccomplished before the mission deployment. Multiple large solar arrays have their own

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risk factors as well and the deployment of these items by crew and or tele-presencerobotics can reduce risk and maximize mission success. We propose as a criticalcomponent of our study that we look to the relative value and safety of a crew assembledsystem versus a crew-assisted assembly utilizing something akin to the NASA Robonautsor similar tele-presence systems developed by DLR.

Figure 6: JSC Robonauts at Work with Langely Space Crane Elements

Figure 7 shows the configuration of the Langley Space Crane

Figure 7: Langley Space Crane with Tip Manipulator

BOOM 3

BOOM 2

BO

OM

1

ROTARY JOINT

JOINT 2JOINT 3

ELBOW JOINT 1

TIP MANIPULATOR SYSTEM

MOBILE BASE

TIP MANIPULATOR SYSTEM

GENERIC SPACE CRANE CONCEPT

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SkyCorp, along with the engineers at Langley, feel that it is very possible to couple theRobonauts with the Space Crane, and the ISS mobile robotics system to make a systemthat will allow the HTARV to be built with a minimum of time and a maximum of safetyto the crew by limiting EVA’s and using tele-operation (software provided by DLR) toaccomplish the task. The worksite, the production planning, and the production sequence

Figure 8: Langley Space Truss Hardware and Packaging

would be worked out during the proposed study. Figure 8 shows the Langley SpaceTruss hardware that is at an advanced state of development at Langley today. Langleyhas an extensive experience base on the use of this hardware, including considerableworksite preparation, timeline planning, as well as packaging for hardware to be used onorbit.

While this is an ambitious undertaking, it specifically compliments the President’s recentannouncement concerning return to the Moon. This system would be made reusable byreplacing Xenon tanks and could be used to boost payloads similar in size to Hubble allthe way to Earth/Moon L1 or even into Lunar orbit, thereby adding a very key componentto a cis-lunar transportation architecture.

Mission Requirements and Analysis

The mission to save Hubble is different from missions to and from higher altitudes. Themission is almost a pure plane change between two orbits at different inclinations and

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altitudes. An extensive analysis effort will be required to optimize the mission in order tominimize V and trip time. Below are some of the requirements and analysis required.

• Plane change required is 23.16 degrees.

• Ascending nodes must also be aligned.

• Current nodal regression rates are 6.487 degree/day (Hubble) and 5.083 degree/day(ISS)

• At these rates, Hubble node will lap ISS node about 6 times in 4 years.

• Plane change delta V is about 3060 m/s. At 90% effectiveness, delivered delta V isabout 3400 m/s. Thrusting 30% of the time (considers ideal thrusting half time pluseffects of shadowing ~ 30% plus contingency) gives return time (Hubble orbit toISS orbit) ~ 1 year.

• Node rate can be modified by altitude change plus strategic wait times, to enablenodal alignment at the conclusion of the return. This must be coordinated with ISSreboosts, which alter ISS nodal regression rate.

• Return trajectory can be optimized for minimum delta V in specified time.

SkyCorp has access to a trajectory and electric propulsion system six-degree of freedomoptimization tool that would be used in concert with Satellite Tool Kit to do the detailedmission planning to execute this mission. We have started with a conservative straw manmission that would be optimized throughout the process to deliver the desired result ofminimum trip time and V.

First Cut Mission Scenario

The HTARV would depart ISS, climb to an altitude of 900-1000 km in order to maximizedaylight time and remove any possibility of crashing into station if a catastrophic systemfailure occurred. Note that the ballistic coefficient is so low that the system would de-orbit quickly in the event of a total system failure. The probability of this is low due tothe fact that the system could be tested at full power while still attached to ISS. TheHTARV would then execute the plane change to move between 51.6 degrees and theHST orbit plane. During the transfer orbit the thrusters would only be fired during thesunlit portions of the orbit.

Care in picking the time of departure could result in a best case beta angle that wouldgive a full sun condition during at least part of the orbit transfer. After reaching the HSTorbital plane the altitude would be reduced to that of HST with great care to make sureand phase the planes properly in order to reduce total system transit time and V. Themission design is a very interesting intellectual exercise that lends itself to a whole groupof trades. Some of the trades are:

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• Optimum departure/return time to minimize eclipse periods and phase with ISSorbit at 51.6 degrees.

• Optimum orbital altitude to minimize eclipse periods, residual atmospheric drag,and assist in minimizing trip time by timing the orbital phasing with ISS.

• Optimize cost of system by trading HTARV power/thrust Vs orbital transit time.• Optimize system design for maximum reuse for ISS re-boost and lunar missions.

The HTARV would then rendezvous and dock with HST using the EVA handholds onthe rear of the bird with grappling accomplished by using the DLR grappling hands orother similar devices. DLR has in development a servicing system that uses multiple“hands” to grapple spacecraft.

After a hard dock has been achieved the system would then begin the transit back to ISS.HST would be made dormant as much as possible and the telescope light door would beclosed. Using electric propulsion there would be no need to furl the solar arrays,therefore the telescope would be able to remain powered during the flight. HST could bemonitored by the Space Telescope Institute to insure proper operation of the telescopeduring the transit period.

The combined system would be first boosted back up to 900-1000 km or anotheroptimum altitude and then the plane change executed over a period of less than one year.Simulations carried out to date by Pratt & Whitney indicate that with the most powerfulsystem that that transit time would be less than 250 days. The telescope would not haveto come all the way back to ISS. It could be brought nearby and then serviced by aShuttle crew. Nothing in this scenario should be construed to suggest that HST beserviced by the HTARV. We feel that this is still pretty much beyond the state of the artin the needed mission timeframe.

During the servicing by the Shuttle or at ISS the tug would be refueled with Xenon.After the servicing is completed the HTARV would boost HST to an orbit to be definedby the science community. The Hubble telescope would then be cut loose and would runon its own systems again. The tug does not have the pointing capability that Hubble doesso it would not be appropriate for that use.

Other Missions for the HTARV

The tug could then return to ISS where it could used for ISS re-boost. The amount ofpower that the system has is entirely adequate for orbital maintenance of the station,which would reduce logistics requirements for wet mass delivered by the Progress orEuropean ATV by a fair margin. Provision could also be made to provide tens ofkilowatts of additional power to ISS. Also, the system could be used as a tug to moveheavy payloads to higher orbits, including an L1 space station. It could also be used tomove fuel and other payloads to the L1 station or to move heavy landers all the way tolunar orbit. The NASA NeXT team has identified a Solar Electric Tug as part of itstransportation infrastructure. For example this tug could take a full up manned Lunarlander to Lunar orbit without a crew and then have a chemical tug take the CEV to lunar

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orbit. Such a tug, along with its siblings could become a vital part of a cis-lunartransportation architecture. This could move up the President’s timetable by years!

Proposed Study to Develop HTARV and Mission

The HTARV team led by SkyCorp Incorporated has already expended significant efforton this mission as well as funded efforts by DARPA and commercial interests in other onorbit assembly and Hall thruster powered systems. Orbital Recovery is in the seriousdesign phase of the sister ConeXpress ORS and other team members not yet officially onboard are interested in joining a funded effort. Orbital Recovery would lead anycommercial participation by ESA in the engineering of the system by the provision oflicensed technology under contract to ORC at this time. ORC also has the contracts andrelationship with Arianespace and ESA for the acquisition of the ATV and the crewedSoyuz.

Conclusion

This mission is achievable. It is ambitious, but there is no part of this system that has notbeen used in at least component form in space or in at least advanced (TRL level 5)development. We feel that it can be built for no greater sum of money than is to beallocated for the de-orbit of Hubble. This system can be built in no more than four yearsand be ready for reliable flight in such a time as to save HST before the failure of all ofits gyros. We urge NASA to budget and allocate funds for performance of a thoroughlydetailed study that would establish the feasibility of our proposed solution.

This is a bold plan is fully in keeping with NASA’s charter and directly applicable tomission to return to the Moon and to go beyond to Mars.

Dennis WingoCEOSkyCorp Incorporated256-533-9967202-321-1087 cellwingod@skycorpinc.com