3. Cargo/Installation Mission System Description

The study team considered many system configurations during the two-month study and identified several workable ways to transport and deploy an 8-meter telescope in front of the existing HST. These configurations are discussed later in this report with some advantages and disadvantages. The approach selected to is based on using as much existing space-qualified hardware as possible to save cost and reduce the associated risks of schedule, cost, and mission success.

Conclusion: There is team consensus that, from a technical standpoint, this job is feasible and could be launched as early as 2006 if proper funding were made available.

3.1. Mirror Configuration for the Cargo Bay

One major challenge was to design a folding 8-meter class mirror that will fit in the Orbiter Cargo Bay with room for the Flight Support System (FSS) required for servicing. The selected mirror configuration is a table-top fold (two folds) of the 8-meter New Primary Mirror (NPM), the New Secondary Mirror (NSM) placed inside the fold of the NPM, and the combination mounted in an existing Space Lab Pallet (SLP). The new mirror assembly mounted on the SLP, the new light-shield support structure, and the New Light-Shield (NLS) will all fit in the Orbiter Cargo Bay. In addition, there is space for a Science Instrument Protective Enclosure (SIPE) mounted to the Flight Support System (FSS) in a way that allows transporting both a refurbished Fine Guidance Sensor (FGS), or a replacement Radial Science Instrument (SI) in its place; and an Axial SI, probably a Coronagraph. We believe all of this will fit in the Orbiter Cargo Bay, fall within the weight restrictions, and allow extra fuel for a re-boost. The "Mission Sequence" section below contains Figures of the Orbiter with the mission cargo on-board and the Installation Sequence.

3.2. Installation Mission Overview

The example installation mission is in four EVA days following routine lift-off, rendezvous, capture, and berthing:

A major challenge for the installation will be containment of the bolts, nuts, and washers that attach the section of the old light-shield to be removed and other debris-containment measures. A large part of a full EVA day is allocated to removing and retaining these items.

Once the upper 3.5-m section of the OLS is removed, zip nuts and quick connections will be used to install the NLS lower structure which supports the deployable NLS. The NLS is deployed radially only at this time and will be deployed axially later, after the new Primary and Secondary Mirrors are in place.

Before the New Primary Mirror (NPM) is installed, the new-mirror-assembly (NMA) interface-ring is installed, it is clamped onto the existing Optical Telescope Assembly (OTA) structure at the top ring that supports the Old Secondary Mirror. The NMA snaps into place on this interface ring with four bolts and the New Light-Shield is deployed axially, completing the assembly.

3.3. Cargo Elements

There are two classifications of cargo elements: Orbital Replacement Unit (ORU) and Space Support Equipment (SSE).

3.3.1. Orbital Replacement Unit (ORU) Description

The ORU complement required to completely outfit the HST10X can be accommodated within one cargo bay without precluding a cargo bay external airlock. The ORU elements are described in this section. The related launch-landing, manipulation, and temporary stowage elements are described in the Space Support Equipment section below.

3.3.1.1. New Primary Mirror (NPM) Assembly Including OTA Interface Ring

The NPM is an 8.4-meter diameter disk approximated by a 757" concave surface, a central hole of 53" radius, and backed by a truncated conical section. This shape is hinged along two length-wise partitions similar to a table with two folding leaves, except in this case the leaves fold upward. The "leaves" are held for launch loads in five places: at the tips where they are attached into the main central panel of the mirror, at the center-top where they are attached to each other with a disposable clasp, and at two intermediate points along their bottom edge where they are supported by snubbers extending from the Space Lab Pallet (SLP) sills.

The NPM integral support structure is a truncated conic section 15" deep at the rim of the center hole and 4" deep at the 8.4-meter periphery. The two fold lines are equally spaced at 58" from the centerline for a total of 116" spread in the field joints equally spaced from the 106" center hole. The 58" partition spacing is chosen for packaging of the NPM onto an existing Space Lab Pallet and to fit within the Orbiter cargo bay doors. The 116" spread could be increased by clipping the opposed edges of the fold-up leaves slightly or performing dynamic load-excursion analysis.

In addition to the primary structural element, the NPM ORU contains the New Secondary Mirror (NSM) Mast latches, an integral hub which clamps onto the OTA Interface Ring, the Clamp, and the OTA Interface Ring itself which contains the discrete OTA spider clamps. The integral hub contains handholds all around the periphery which are canted to be perpendicular to the assembled NPM center of mass to aid in translation onto the HST.

3.3.1.2. New Secondary Mirror/Mast (NSM/M) Assembly

The NSM consists of one integral assembly with three functional zones: the mirror itself, the tubular Mast, and the gussets which make the mast rigid to quell on-orbit disturbance-resonance response. The mast gussets align in a cursory sense with the existing OTA spider leg geometry to avoid light blockage not already incurred by those existing OTA structural members. Each mast gusset terminates in a latch which secures to the NPM integral hub top surface. The NSM/M contains recessed handholds near the center-of-mass to enable EVA assembly by astronauts.

3.3.1.3. New Light Shield (NLS) Base

The NLS 8.7-meter base fits the flange previously occupied by the Old Light Shield (OLS) and consists of a circular array of NLS support trusses and a roll-up Solar Array with a center hole of 125". The solar array serves to function as the NLS aft close-out for stray light on the backside, and as a source of power augmentation on the exterior side, which faces aft on HST. The power afforded offsets a reduction in normal SA-3 output due to SA heating caused by the NLS cylinder presence. The trusses connect to HST via flange holes which are left unoccupied by the removal of the Old Light Shield, and to the next flange aft on HST. The augmentation SA has integral rods which clip into a bottom channel of each truss. The existing P601 interface is a likely candidate for entering the augmentation power contribution.

3.3.1.4. New Light Shield (NLS) Cylinder

The NLS cylinder is a two-stage unfurlable device which deploys to provide a Multi Layered Insulation (MLI) cocoon 8.7-meters in diameter and 15 meters long. The inside surface is optically black to suppress non-collimated stray light. At this length, the cylinder reduces Earth-albedo thermal perturbations sufficiently for a Zerodur mirror surface to maintain distortion specifications for earth disk intrusion into the line of sight. The stowed NLS cylinder is four meters in diameter and one meter thick. The Astromast canisters, for axial NLS deployment, account for the majority of the mass which is concentrated in the center third of the overall cylinder. For radial deployment, bi-stable folded struts are released and the full diameter array of Astromast boom canisters plus accordion (collapsed) MLI is formed. Subsequently, the circular array of Astromast booms are deployed from their canisters, simultaneously, and the MLI is straightened to the flush, 15-meter configuration. No active elements are expected to be included in the deployed NLS cylinder length.

3.3.1.5. Upgraded Fine Guidance Sensor (FGS)

An FGS upgraded for fine line-of-sight control sensing, or a Radial SI to do so, will be installed in place of FGS #3 (#3 ideally, due to its proximity to NICMOS for installing SIís with minimal rotations of the grappled HST). This Radial SI could contain the wave front correcting optics and active processing to govern the NPM actuators. Proximity of the Radial SI drawer to the NPM base enables a direct control path connection between these two elements without burdening the existing HST harnessing system. Externally, this is a standard SI Change-out as performed for SM-1, 2, 3A, etc. and is performed within prescribed parameters. The Space Lab Pallet will contain standard parking fixtures to enable the swap.

3.3.1.6. Replacement Axial Science Instrument

A replacement Axial SI can be installed in place of the present NICMOS SI. This is a standard SI Change-out as performed for SM-1, 2, 3B, etc. and is performed within prescribed parameters. The now unoccupied Space Lab Pallet will contain standard parking fixtures to enable the swap.

3.3.1.7. Kits for Returned ORU (Old Light Shield including Aperture Door)

In the interest of orbital debris prevention, the removed Old Light Shield (OLS) section will be stowed for earth return in a station behind the Flight Support System (FSS). This is aided by the fact that the OLS intrinsically contains one scuff plate and trunnion and another scuff plate on tower ideally suited to accept a second longeron trunnion installation. Another benefit of these existing features is that they contain an axis which points through the center of mass of the removed OLS, thus exhibiting an ideal perch for the Grapple Fixture which is necessary for translation to the berthing latches. Thus, the first of two kits needed to return the OLS consists of a exchange of the old scuff plate for a device which is first a grapple post and then, after positioning is achieved, deploys a standard trunnion pipe out around the pin to become a portside longeron trunnion. The second of two kits is a light duty structural element consisting of a 125" (after unfolding) spanner which bolts in two places to the OLS flange and presents a keel trunnion interface in the center. HST will be tilted forward to the standard 43.8 degree position to provide clearance for the Remote Manipulater System (RMS) arm to install the OLS behind the FSS for return to earth.

3.3.1.8. Miscellaneous Small ORUís

Ample footprint and load carrying capability exists on the fore and aft faces of the Space Lab Pallet for accommodation of small ORU items such as the Ion-Engine Stationkeeping System (IESS) thruster packages and associated harnessing.

3.3.2. Space Support Equipment (SSE)

The SSE configured for the HST10X mission consists largely of re-flown elements integrated together with a few new devices which are necessary to fit the ORU complement. The discussion below will be done per "carrier", two carriers are expected to be necessary to conduct the mission. The discussion will differentiate the re-flown SSE elements from the new devices.

3.3.2.1. New Mirror Assembly (NMA) Carrier

The NMA Carrier consists of a basic Space Lab Pallet which is generically available from Kennedy Space Center (KSC); existing examples in use by HST Servicing are pallets built-up into the ORU Carrier (ORUC) and Rigid Array Carrier, either of which could be stripped down to provide the HST10X mission pallet.

The New Primary Mirror (NPM) carrier components are a new design and the need for load isolation will be mitigated by member sizing for adequate strength. Existing parking fixtures from the ORUC can remain to serve as temporary parking for the new axial SI and new radial SI swaps. For temporary overnight stowage of the NLS cylinder, a stowage fixture with Intra-Vehicle Activity (IVA) jettison capability will be required as a new device.

Footprint and load carrying capability on the fore and aft faces of the Space Lab Pallet will accommodate the stacked trusses for the NLS base framework. These trusses are 112" long, clipped, slender triangles with a base of 0.5 meter and a per-truss thickness of one inch.

Another new device required for the NMA Carrier is a slotted, circular tub which emulates the OTA Interface Ring clamp interface, and which contains a simple, EVA actuated scissors jack. The OTA Interface Ring will be assembled for transport upside down to the Mast mounting surface of the NPM for the launch environment. It will be removed before the other parts of the NPM for installation onto the HST OTA spider. The scissors jack will subsequently be elevated to enable the leaves to be deployed and locked down into the operational position clear of the Orbiter longeron sill. This elevation also exposes the handholds which are built into the underside of the NPM central member, these are used to transfer the complete NMA to the HST after the OTA Interface Ring has been installed.

The tub is slotted so the New Secondary Mirror/Mast (NSM/M) Assembly can reside in the new tub, under the NPM leaves, for launch. EVA clasps hold the NSM/M Assembly into the tub slots. After the NPM has been elevated and the leaves positioned, the New Secondary Mirror/Mast Assembly is unclasped and translated to the latch interfaces in the concave center of the NPM. It is possible that the leaves can be partially deployed, the New Secondary Mirror/Mast assembled, and then a full leaf deployment implemented, in order to preclude the leaves from interfering with New Secondary Mirror/Mast (NSM) Assembly translation.

After the New Secondary Mirror/Mast is assembled, the entire NMA is grappled and translated for installation on HST. The scissors jack is retracted (or not) and it, the slotted tub, and the basic pallet are returned to earth.

Mass Properties for the loaded NMA Carrier are as follows: Basic Space Lab Pallet 1,450 lbs., ORU complement 4,000 lbs., mission peculiar equipment (slotted tub with NSM/M clasps, scissors jack, parking fixtures, base truss work latches, NPM sill latches, Ion Engine thruster/harness enclosure) 700 lbs., for a total NMA Carrier weight of 6,150 pounds.

3.3.2.2. Flight Support System with Cradles A-B-Aí and integral BISIPE

The normally flown Flight Support System (FSS) Cradle A will be augmented with existing Cradles B and Aí to create enough length and load carrying capability for the additional SI swaps and the furled New Light Shield (NLS) components. All normal HST pivot, rotate, and Berthing and Positioning System (BAPS) Support Post (BSP) capabilities are retained via the Cradle A Berthing and Positioning System. The new SIís are carried aloft in the existing Bolted Interface SI Protective Enclosure (BISIPE) which has been utilized on SM-1, SM-2, and SM-3A. The BISIPE consists of an Axial SIPE (ASIPE) and an FGS SIPE (FSIPE) bolted back to back.

The BISIPE for HST10X will feature a truncated FSIPE in that the unused volume originally provided for the WFPC radiator is eliminated by replacing portions of the honeycomb dust cover with a flat, MLI flap. A new bracket is required to accommodate the BAPS Support Post (BSP) with the BISIPE. The load limits of the existing SI latches, a combination of wire-rope isolators and weight budget placed on the new SIís, will permit use of existing SI latch assets within hardware limitations.

The pre-deployed New Light Shield (NLS) Cylinder package will be stowed in a fashion similar to that which was constructed for an FGS accommodation on SM-1. This was a wire-rope isolated plate mounted to the aft face of the FSS Cradle A centerline to the cargo bay. The mass parameters of the New Light Shield cylinder comply with the previously designed FGS accommodation. After the package has been staged to the parking fixture, the residual carrier plate is flat enough against the FSS that the Old Light Shield may be stowed aft of the FSS on EVA Day 1. The parked NLS will be deployed on a subsequent EVA day.

The perch for the furled NLS Base package is a mandrel support built to place the base on top of the ASIPE lid. The furled base, with rods inside, takes the shape of a truncated cone 112" long and 1 meter in diameter at the large end, and 0.5 meter diameter at the small (inboard) end. The mandrel will face such that the large-diameter-end mandrel bolts to the ASIPE end plate and the small-diameter-end mandrel bolts to the FSIPE honeycomb dust cover, offset from the centerline to avoid interfering with the BSP. After the furled base has been removed, the mandrels pivot out of the way via pip-pin adjustments.

Mass properties for the loaded FSS are as follows: FSS Cradles A-B-Aí 8,525 lbs., loaded BISIPE 3,800 lbs., Aeroflex isolators for BISIPE 250 lbs., loaded aft carrier system 1,000 lbs. (including ORU), for an FSS total of 13,575 pounds.

3.4. Mission Sequence Description

A mission sequence was designed to test and demonstrate that unpacking, configuring, and temporary stowage have been properly accounted for in the design of the Orbital Replacement Unit (ORU) pieces and the layout of the System Support Equipment (SSE) to accommodate the ORUís and the HST within the confines of the Orbiter cargo bay.

The lift-off mass total for the payload is 19,725 pounds. Orbiter kits such as the Standard Mixed Cargo Harness and retention latches for the New Mirror Assembly (NMA) Carrier, FSS, and Old Light Shield (OLS) (for return to Earth only) are booked against Orbiter vehicle mass properties.

Following routine lift-off, rendezvous, capture, and berthing:

On EVA Day 1, tilt HST to the 43.8 degree position. Prepare the OLS for removal and stowage by replacing the old scuff plate with Kit #1 which serves as the Grapple Fixture (GF) pin and subsequently the slide-out longeron trunnion. Stage the Keel trunnion Kit #2.

Translate the NLS cylinder package from the back of the FSS to the jettison-capable parking fixture on the NMA Carrier.

Unbolt the OLS from the HST at 106 places. Install Kit #2. Stow the OLS into the starboard and keel trunnion Shuttle latches via RMS operation, and motor those latches closed. Deploy the port trunnion from Kit #1 and motor that trunnion latch closed as well.

While in a mode where rotating HST is convenient, install the ion thrusters. The large diameter threaded holes in the existing HST trunnion sockets make ideal mechanical mounts for the ion thrusters. P601 is co-located with the starboard socket and circumference harnessing could route power to the other ion thrusters, bussed off of the first installation.

3.4.2. EVA Day 2, Install New Light Shield, but do not Deploy Axially

On EVA Day 2, remove the truss packages from the faces of the NMA Carrier and install them in a dispersed fashion around the OLS unoccupied flange, utilizing the FSS Rotator for access.

Remove the NLS furled base from the SIPE mandrel and install the rods individually to the truss work, again utilizing the FSS Rotator.

Remove the parked NLS cylinder package from the NMA Carrier fixture and cord-lock it in-place on HST, centered over the 125" flange hole. Send the command to deploy the radial component of the NLS cylinder package and adjust the cord locks appropriately to center the flat cylindrical array of Astromasts onto the base. Fasten the Astromast canisters to the base at appropriate truss interfaces and inspect the serve of the Multi-Layer Insulation (MLI) for probability of clean axial deployment.

During the overnight period following EVA Day 2, and preceding Day 3, the augmentation solar array power Functional Test will be completed.

3.4.3. EVA Day 3, Prepare and Install New Mirror Assembly

On EVA Day 3, elevate the scissors jack to enable petal positioning. Fold down and latch the starboard petal.

Two EVA personnel will now work as EVA-RMS (stationed on the robot arm) and EVA-FF (Free Floater). EVA-RMS works in conjunction with the Remote Manipulator System Operator, who is conducting Intra-Vehicular Activity (IVA).

Having gained access to the NMA/OTA Interface-Ring via starboard petal positioning, remove the interface ring from the launch position on the NPM latches. IVA RMS Operator/EVA-RMS team will now translate the ring to the tilted HST flange interface (actually the OTA spider). Clasp the ring to the spider using the four OTA Clamps.

For the NSM/Mast, EVA-FF will unclasp the NSM/Mast assembly from the slotted-tub devices and the IVA RMS Operator/EVA-RMS team will translate it up and over the port wing.

While staged in this manner, EVA-FF will fold down and latch the portside petal of the NPM. The IVA RMS Operator/EVA-RMS team will then translate and rotate (by hand) the NSM/M in-board to match up the latch sets to the NPM. EVA-FF engages the four latches which anchor the NSM/M gussets to the mirror base. The New Mirror Assembly is now assembled.

The IVA RMS Operator/EVA-RMS team now maneuvers EVA-RMS to the underside of the New Mirror Assembly (NMA) to enable grasping of the underside handholds most suited for translation to HST. EVA-FF releases the single-fastener clamp holding the NMA to the Carrierís tub. Closing of the scissors jack is not necessary for landing.

While the IVA RMS Operator/EVA-RMS team translates the NMA to HST, EVA-FF translates their person to the flange as well. Meeting at the flange, the IVA RMS Operator/EVA-RMS team positions the NMA with EVA-FF assisting in fine- motion detail. After nesting the clamp halves, EVA-FF closes the single fastener clamp, gaining access via standard hand- tool extensions. Electrical connectors are mated and the command to activate the axial-deploy portion of the NLS is issued.

3.4.4. EVA Day 4, Swap SIís

On EVA Day 4, swap the new Axial SI for NICMOS and swap the new Radial SI for FGS #3. These are standard SI replacements as conducted on SM-1, SM-2, and SM-3A/B. Co-location of NICMOS and FGS #3 expedite this operation.

3.4.5. Deploy HST

Following overnight Functional Tests of the wavefront correcting actuators and the new SI's, HST will be deployed via the RMS.

3.5. Flight System & Servicing Remaining Issues

There are several interfaces such as electrical connectors and wave guides that need to be disconnected and reconnected when the HST10X is installed. We may need to move the magnetic torquers up onto the new light shield and probably reconnect the magnetometer connector to a new device. The wave guide will probably need to be reconnected to some kind of low gain antenna.