Project Overview - Hubble Telescope Autonomous Rescue Vehicle (HTARV)
Introduction
This document outlines a proposed capability and mission to rendezvous and dock with
the Hubble Space Telescope (HST) and thereafter safely and cost effectively extend its
operational life. A Hubble Telescope Autonomous Rescue Vehicle (HTARV), derived
and assembled from a number of existing orbital vehicle systems will be used to transport
HST to the International Space Station (ISS) for servicing. Subsequently the HTARV
will further boost HST to a higher operational orbit. This mission concept is compelled
by widespread public desire to operationally sustain the greatest deep space telescope for
the continued advancement of science and public benefit. Over the past 14 years HST has
produced untold scientific benefit and understanding of the cosmos, as well as the most
extraordinary 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 to
NASA’s Hubble Space Telescope Rescue RFI. These entities and their prospective roles
are:
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SkyCorp, Incorporated (Huntsville, AL)
o Program Team Leader
o HTARV System Design
o Hall Thruster System Optimization
o Flight Computer and Navigation System
Orbital Recovery Corporation (Washington, DC)
o Commercial licensee for DLR Intellectual Property TRL level 7 for
robotics, rendezvous and docking
o Commercial link to ESA
o Ariane V Contract
NASA Langley Space Center (Langley, VA)
o Systems Engineering
o Space Truss Intellectual Property
o On orbit construction expertise
NASA Johnson Spaceflight Center (Houston, TX)
o Robonauts
o EVA Systems
NASA Goddard Spaceflight Center (Greenbelt, MD)
o Hubble Systems
o Hubble Servicing
Pratt & Whitney
o Hall Thruster Propulsion System
HawkEye Systems (Alexandria, VA)
o EVA Experience
o EVA Planning
o 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 based
rescue of HST while detailing contingency plans that move HST to a 100-year
orbit.
2. Work with NASA to develop a credible scenario enabling HST refurbishment
at 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 and
development effort in cooperation with our other team members as well as partnership
with Goddard Space Flight Center Hubble servicing team. This is a serious effort and
requires 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. SkyCorp
has the financial wherewithal to fund this effort in a normal contract environment of
payment on 30-day increments or less. SkyCorp is a member of the DoD Central
Contractor Registry (CCR) database and has all export licenses needed to work with
Orbital Recovery Corporation. Any additions can be handled through amendments to
existing Technical Assistance Agreements.
Request for Information Background
As a result of recent budget announcements, NASA has come under significant public
pressure and political interest in response to the decision to cease HST support. A senior
NASA official recently remarked: “You know we cancelled the Space Shuttle, the Space
Station, and Hubble programs- guess which one everyone is up in arms about?” In the
past six months, two companies, SkyCorp Incorporated and Orbital Recovery
Corporation, have met with NASA officials regarding Hubble. The purpose of these
contacts has been to brief the Agency on viable options that may be available to continue
Hubble operations, at considerably less expense to the federal budget.
The principal reason for cancellation of the SM4 HST mission is due to the
recommendation of the Columbia Accident Investigation Board (CAIB) to conduct Space
Shuttle 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 been
proven. This decision opens the door for creative ways to salvage Hubble from de-orbit
and certain destruction. This document proposes a solution that does not depend on use
of Shuttle Orbiters. When established in the same orbit as ISS, and moved to a position
in close proximity to ISS, NASA HST could be readily serviced before subsequent
relocation to a higher operating orbit. Proposed to accomplish the HST repositioning
maneuvers is a multi-purpose, multi-use HTARV tug. The HTARV will be used to save
HST, 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 is
designed for servicing of currently orbiting and planned GEO communications
spacecraft. “ConeXpress” Orbital Recovery System (ORS) is a robotic system that is
designed 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 proceeding
into the production of the ConeXpress ORS. The European Space Agency (ESA) is
participating in development of the ORS and is providing matching funds under the
authority of its Public/Private Partnership program. ORC has recently signed a contract
with the DLR (German Space Agency) to license the use of its robotics capabilities and
Rendezvous-and-Capture software for use in the ConeXpress ORS. Other advanced
rendezvous hardware (cameras and a communication system), to be provided by a
Japanese firm, Astro Research Corporation, will be incorporated into the system. DLR,
whose robotic experience began in 1983 with the Spacelab D2 mission, has substantial
experience with on orbit servicing systems and tele-operation.
DLR built a robot (that flew on the larger spacecraft and the GETEX experiment) which
examined the dynamics of how a robotic arm influenced the overall stability of a coupled
pair of spacecraft. DLR and its industrial partner Kayser Threde are currently working
closely with ORC in development of the ConeXpress ORS. Figure 3 is a rendering of the
joint DLR/NASDA ETSVII (GETEX) mission in 1998.
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The current configuration of the ConeXpress ORS is not capable of performing the
Hubble Rescue mission because of its limited size, power, and thruster performance.
However, a significant portion of the technology that is incorporated into the system is
directly applicable to an upgraded ORS that is designed to in response to the
requirements for a Hubble rescue mission. In particular, a number of DLR’s advanced
robotics 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 that
will be flown in a joint venture with the Russian Space Agency. DLR will launch and
operate an advanced robot on the mission that is designed to grapple a companion
spacecraft. Among other objectives, DLR will gain invaluable data and experience in
understanding the dynamics of a coupled pair of orbiting spacecraft. Within the next 18
months, and preceding the TECSAS mission, a test version of this system will be
delivered to ISS to prove out operation of the robotic joints. This system will be mounted
on the outside of the Russian Zvezda module and undergo a set of activities that are
planned to accurately characterize operation of DLR’s robotic arm joints in the actual
mission operating environment. Successful achievement of the planned objectives will
elevate maturity of this system from its current Technology Readiness Level (TRL) 5 to
TRL 7. The subsequent TECSAS mission will further this maturing process and
demonstrate 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 the
original Spacecraft Life Extension System (SLES), developed by ORC, could be readily
adapted for use in the HST rescue mission.
SLES Heavy (HTARV) To the Rescue
At the outset of the Orbital Recovery System development process, SkyCorp worked
directly 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 rescue
missions 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 to
rendezvous with ComSats located in intermediate LEO orbits of any inclination or GTO
orbits, and move them to GEO. Mission operations such as these would likely require
addition of velocity increments (V’s) that are on the same order of magnitude as a
Hubble rescue mission would require. Figure 5 is an illustration of the SLES as it is
envisioned 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 V
required to move Hubble from its present orbit at 28.5 degrees to the ISS orbit of 51.6
degrees is approximately 3.4 km/sec (at 90% thrust efficiency). Theoretically, a 10
kilowatt SLES (0.5 Newtons thrust) could accomplish this task, but it would require a
very long time, measured in multiple years, to complete the transfer. Therefore a more
powerful version of the SLES, henceforth referred to as the HTARV, is needed to
perform and complete the mission within an acceptable time period, generally envisioned
as one year or sooner.
Preliminary calculations indicate that to move the system within a year long mission, a
system that delivers at least 2 Newtons and possibly as much as 5.6 Newtons of thrust is
required. This is currently achievable, but the power required to do so is between 44 and
88 kilowatts. Current solar array technology would require over 250 m2 of solar array for
the 88 KW worst case power demand. This is a very sizeable solar array, which would
quite likely be difficult to fabricate and assemble, verify, and launch, if confined to a
Delta IV class vehicle. Proposes is the use of two to four pairs of solar arrays adapted
from Boeing’s “702 Series” GEO ComSat. A single Boeing 702 solar array delivers peak
performance of 22KW, thus two to four sets would provide the 44 to 88 KW BOL power
requirement. The 702 solar arrays are currently operating successfully on orbit in ComSat
applications, and therefore are at TRL 9. It is planned to scale up these flight elements by
a factor of 4 worst case to meet the projected mission requirements.
Planned deorbit of the HST bounds the timeframe that is available to complete system
scaleup and any proof of concept requirements. Success of this approach will depend on
the ability to minimize new development. For this proposed mission to be successful, it is
anticipated that Hubble would need to be retrieved before it descends below an altitude of
~ 250Km, wherein after increased atmospheric drag would begin to severely hamper
effective 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 effective
benefit 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 to
accomplish this mission are well within c what is commonly recognized as the current
state of the art and meet or exceed NASA’s HST Rescue Mission RFI requirements of
TRL 5 or greater. A companion file to this RFI response, (HLESweights.xls) provides a
preliminary weight budget for the system, including provision for the required Xenon wet
mass. The referenced file also catalogs the assessed TRL levels of each of the HTARV
subsystem elements. A second included file (HSTrescue.ppt) d provides detailed mission
implementation data associated with the performance of the propulsion system and
mission 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 of
340 Km at 51.6 degrees requires a propulsion system of considerable capability and
capacity. Hubble weighs in excess of 11,000 Kg, which requires system performance that
lies well outside the capability of any currently available propulsion system. To
underscore this point, Centaur, the most energetic upper stage currently available for
transfer of ComSats to GEO is able to transport a 5,000 + / - Kg spacecraft. This requires
only 1.5 Km/sec of V. Application of an equivalent amount of energy would result in
only 0.7+ / - Km/Sec of V, or only about 15% to 20% of the total energy required to
move HST to the orbital plane of ISS. Inasmuch as Centaur also performs a plane change
from 28.5 degrees to 0 degrees (albeit at a GEO altitude where energy demands are much
reduced), there is comparatively even more performance contained in Centaur. It should
be possible, then, to increase the scale of a Centaur Tug to perform most, if not all of the
required transfer mission. This HST Centaur Tug would be a stretched version whose
substantially increased fuel volume would consume the entirety of a Delta IV-H payload
bay. However, HST’s deployed solar arrays impose a mission operating constraint that
precludes use of a larger scale Centaur. Acceleration loads imposed on HST would
require retraction and redeployment of its solar arrays, considered to be an untenable risk
factor, and moreover, Hubble housekeeping functions require that power must be
continuously applied to the spacecraft. Even if capable of retraction and redeployment,
HST would founder. A corollary challenge would be excessive boiloff losses of cryo
propellant that would severely limit the time available to rendezvous, dock, and move
HST to the ISS inclination.
An unrelated (to HST rescue), but long-term disadvantage of a Centaur based system
would be that it has no capability for reuse for Lunar transfer missions without a
companion capability to replenish both LOX and liquid Hydrogen while on orbit. This
capability is strongly needed in support of the Administration’s Space / Lunar
Exploration 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, a
far less hazardous and cost effective refueling capability with more long term potential
for 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 achievable
and presents the least degree of consequential risk to the telescope itself. One detriment
associated with EP is the significantly increased transit time between the two orbits. In
discussing electric
thrusters a differentiation must be made between a grided ion system such as was used
for the Deep Space 1 mission and Hall Effect thrusters that were originally developed in
the former Soviet Union. Response to NASA’s RFI does not warrant an extensive
discourse on the relative merits of Hall thrusters versus Grided Ion thrusters. However, it
is plainly evident that the Hall thrusters provide significantly greater thrust, albeit at a
lower Isp than grided ion thrusters. Hall thrusters deliver Isp that is 4 to 6 times greater
than that of chemical propulsion systems therefore requiring much less propellant than
for a chemical system for the Hubble rescue mission. However, it has been the combined
experiences of both SkyCorp and ORC experience in prior design circumstances that
grided ion thrusters with high Isp and very low thrust simply do not provide sufficient
performance 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 shown
in figure 6. This thruster delivers Isp of 1875 seconds at a thrust of approximately 1.42
Newtons while consuming 22 KW of input power at an output from the power processor
of 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 necessary
to move a HST class spacecraft to its new orbit. The voltage applied to the Hall thruster
could be reduced in order to minimize fuel consumption, at the expense of increased
transit timelines. Optimization of this tradeoff is to be further studied as part of the
proposed effort.
Power System
The propulsion system is not the critical path system for this development. The most
challenging aspect to the spacecraft is the power system, including the solar arrays, array
pointing, and power interface to the T-220HT thrusters. An important starting point that
would 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 full
sets of solar arrays, which is within Boeing’s (SpectraLab) production capabilities,
especially in the current market for commercial ComSats. Since the HTARV would not
be leaving LEO in order to perform the Hubble mission there is little concern relative to
solar array degradation with the use of the proposed solar panels.
A very robust and failure tolerant system could be accomplished through implementation
of an electric propulsion system design that is analogous to NASA’s Saturn 1 launch
vehicle. In this adaptation, each pair of EP engines would be paired with discrete and
independent solar array and power processing systems connected to the clustered pair of
T-220HT thrusters. This would avoid reliability problems associated with the
aggregation of 44-88 kilowatts of power into a single power system and subsequent
switching and distribution of power into separate thrusters. A byproduct of this would be
that each solar array-power processor-thruster pair has its own built in redundancy. This
treatment would introduce approximately 200-Kg weight penalty, but would appreciably
increase system reliability. The mass penalty is minimal in a total system (including
HST) whose projected mass is on the order of 17,000 Kg. Some cross strapping would
be required so that a failure of a thruster group would not eliminate the ability to use the
fuel 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 that
can be integrated on a launch vehicle, deployed, and operate reliably. This is not
impossible and should be studied with equal consideration to any other approach.
However, such a system lends itself to an on-orbit assembly approach whereby the
system 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, the
much 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 more
reliable deployment of the solar arrays and thruster booms, and an opportunity to pretest
before 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 system
would not have to qualify for the full dynamic environment or the volumetric limitations
of existing launch systems due to the use of SkyCorp’s patented vibration reduction
packaging for protecting subsystem components for launch.
With the total cost of this system is constrained by choice to no greater than that budgeted
for de-orbit of Hubble, HTARV system requirements, costs and resultant schedules could
be very tightly controlled while also producing a system that has multiple uses beyond
the Hubble mission.
Because the Administration’s policy is to reserve use of the remaining Space Shuttle
orbiter fleet as much as possible for ISS completion, reliance on it should be held to a
minimum for this mission. A preliminary concept would be that the HTARV
components be sent up in a European ATV or Russian Progress vehicle specifically
purchased for this mission. An alternative system such as the Kistler K1 or the future
SpaceX Falcon V could be used as well for this purpose, however, viability of both
would need to be vigorously assessed. It may be that as a minimum, the solar arrays
could be flown on a logistics mission where the Shuttle carries the MPLM. In this case
the Lightweight MPESS Carrier (LMC) that flies in the rear bay of the Shuttle would be
used. It normally does not count fully against payload weight due to its role replacing
ballast mass for Shuttle CG optimization. These alternatives would have to be seriously
addressed in the context of the Shuttle’s role in completing the construction of ISS before
its retirement.
The crew for the assembly process would be transported to ISS in a Soyuz vehicle that is
commercially purchased for this specific purpose. Discussions with Energia indicate that
with an 18-month lead-time, this is very achievable. Both American and Russian
robotics assets on ISS would be used to support the mission. All three Soyuz crew
persons would be tasked to work on this project, with two of them being American and
one Russian. The crew would stay for up to two weeks and execute EVA’s to assemble
the 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, and
thereafter robots such as the NASA Robonauts used to assemble truss elements for the
spacecraft, deploy the solar arrays, and test the system. The worksite would be set up
with at least one NASA Langley Space Crane, the existing ISS robotics systems, as well
as any other robotic assistants needed. The crew persons would either assist the
Robonauts or be there in case of some difficulty. This would help to maximize crew
safety and help to further develop these techniques for the assembly of future lunar
mission components. This would be further developed during the study phase. NASA
Langley 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 into
the 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 be
accomplished 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-presence
robotics can reduce risk and maximize mission success. We propose as a critical
component of our study that we look to the relative value and safety of a crew assembled
system versus a crew-assisted assembly utilizing something akin to the NASA Robonauts
or 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
GENERIC SPACE CRANE CONCEPT
BOOM 2
BOO
M1
BO
JOINT 2
OM
3
JOINT 3
TIP MANIPULATOR
SYSTEM
ELBOW JOINT 1
ROTARY JOINT
MOBILE BASE
TIP MANIPULATOR
SYSTEM
Figure 7: Langley Space Crane with Tip Manipulator
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SkyCorp, along with the engineers at Langley, feel that it is very possible to couple the
Robonauts with the Space Crane, and the ISS mobile robotics system to make a system
that will allow the HTARV to be built with a minimum of time and a maximum of safety
to the crew by limiting EVA’s and using tele-operation (software provided by DLR) to
accomplish 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 Space
Truss hardware that is at an advanced state of development at Langley today. Langley
has an extensive experience base on the use of this hardware, including considerable
worksite preparation, timeline planning, as well as packaging for hardware to be used on
orbit.
While this is an ambitious undertaking, it specifically compliments the President’s recent
announcement concerning return to the Moon. This system would be made reusable by
replacing Xenon tanks and could be used to boost payloads similar in size to Hubble all
the way to Earth/Moon L1 or even into Lunar orbit, thereby adding a very key component
to a cis-lunar transportation architecture.
Mission Requirements and Analysis
The mission to save Hubble is different from missions to and from higher altitudes. The
mission 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 to
minimize V and trip time. Below are some of the requirements and analysis required.
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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 is
about 3400 m/s. Thrusting 30% of the time (considers ideal thrusting half time plus
effects of shadowing ~ 30% plus contingency) gives return time (Hubble orbit to
ISS orbit) ~ 1 year.
Node rate can be modified by altitude change plus strategic wait times, to enable
nodal alignment at the conclusion of the return. This must be coordinated with ISS
reboosts, 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 freedom
optimization tool that would be used in concert with Satellite Tool Kit to do the detailed
mission planning to execute this mission. We have started with a conservative straw man
mission that would be optimized throughout the process to deliver the desired result of
minimum trip time and V.
First Cut Mission Scenario
The HTARV would depart ISS, climb to an altitude of 900-1000 km in order to maximize
daylight time and remove any possibility of crashing into station if a catastrophic system
failure occurred. Note that the ballistic coefficient is so low that the system would deorbit quickly in the event of a total system failure. The probability of this is low due to
the fact that the system could be tested at full power while still attached to ISS. The
HTARV would then execute the plane change to move between 51.6 degrees and the
HST orbit plane. During the transfer orbit the thrusters would only be fired during the
sunlit portions of the orbit.
Care in picking the time of departure could result in a best case beta angle that would
give a full sun condition during at least part of the orbit transfer. After reaching the HST
orbital plane the altitude would be reduced to that of HST with great care to make sure
and phase the planes properly in order to reduce total system transit time and V. The
mission design is a very interesting intellectual exercise that lends itself to a whole group
of trades. Some of the trades are:
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Optimum departure/return time to minimize eclipse periods and phase with ISS
orbit 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 on
the rear of the bird with grappling accomplished by using the DLR grappling hands or
other 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 be
closed. 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 be
monitored by the Space Telescope Institute to insure proper operation of the telescope
during the transit period.
The combined system would be first boosted back up to 900-1000 km or another
optimum 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 powerful
system that that transit time would be less than 250 days. The telescope would not have
to come all the way back to ISS. It could be brought nearby and then serviced by a
Shuttle crew. Nothing in this scenario should be construed to suggest that HST be
serviced by the HTARV. We feel that this is still pretty much beyond the state of the art
in 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 defined
by the science community. The Hubble telescope would then be cut loose and would run
on its own systems again. The tug does not have the pointing capability that Hubble does
so 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 of
power 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 or
European ATV by a fair margin. Provision could also be made to provide tens of
kilowatts of additional power to ISS. Also, the system could be used as a tug to move
heavy payloads to higher orbits, including an L1 space station. It could also be used to
move fuel and other payloads to the L1 station or to move heavy landers all the way to
lunar orbit. The NASA NeXT team has identified a Solar Electric Tug as part of its
transportation infrastructure. For example this tug could take a full up manned Lunar
lander 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-lunar
transportation 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 effort
on this mission as well as funded efforts by DARPA and commercial interests in other on
orbit assembly and Hall thruster powered systems. Orbital Recovery is in the serious
design phase of the sister ConeXpress ORS and other team members not yet officially on
board are interested in joining a funded effort. Orbital Recovery would lead any
commercial participation by ESA in the engineering of the system by the provision of
licensed technology under contract to ORC at this time. ORC also has the contracts and
relationship with Arianespace and ESA for the acquisition of the ATV and the crewed
Soyuz.
Conclusion
This mission is achievable. It is ambitious, but there is no part of this system that has not
been 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 be
allocated for the de-orbit of Hubble. This system can be built in no more than four years
and be ready for reliable flight in such a time as to save HST before the failure of all of
its gyros. We urge NASA to budget and allocate funds for performance of a thoroughly
detailed 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 to
mission to return to the Moon and to go beyond to Mars.
Dennis Wingo
CEO
SkyCorp Incorporated
256-533-9967
202-321-1087 cell
wingod@skycorpinc.com
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