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The first underwater sim for the final Hubble EVA BY CRAIG COVAULT SPACEFLIGHT NOW Posted: May 10, 2009
He had just performed the final Hubble underwater simulation in a neutrally buoyant space suit. Massimino described it as "an historic day," coming more than 25 years since the start of such space suited underwater training sessions for Hubble mission astronauts. It was equally poignant for this editor at Spaceflight Now. That is because while Massimino performed the last Hubble underwater simulation, I had performed one of the first. I drew that lucky assignment in 1982 as senior space editor of Aviation Week and a Hubble extravehicular activity (EVA) test subject at the Marshall Space Flight Center tank in Huntsville. Ala. My underwater EVA, with Marshall engineer Fred Sanders marked the first complete end-to-end removal and replacement of a Hubble Fine Guidance Sensor (FGS) from the telescope's radial equipment bay, midway up the side of the observatory. That same task in space is now planned to be the final STS-125 EVA for entire Hubble program. Neutrally buoyant spacesuit runs are major operations involving extensive safety and operational support. Mine had a total of 20 personnel in scuba gear, all with specific roles to play. Sixteen of these divers were safety, utility and photo personnel split equally between Sanders and myself. Another four were Essex corporation engineers monitoring how our space tools performed. A test-conductor topside also acted as our "IV" intra-vehicular coordinator "inside the shuttle middeck". We also had a space suit technician that monitored the temperature of the 20 gal./min. water flow through the suits' liquid cooling garment. And we had a flight surgeon monitoring our heart rates and overall metabolism derived from the temperature of the returned cooling water. The water was as cold as 45F when it went into the cooling garment--long underwear laced with tiny hoses. We would call for "warmer or colder" and when working hard, the colder the better. The test generated wide interest among Marshall space telescope engineering personnel since it was the first to demonstrate a timelined pallet-to-telescope instrument transfer with space-suited subjects. Numerous engineering personnel observed the test via closed circuit television. "Air to ground" communications were maintained with the simulation control room and the divers could also hear what we were saying through underwater speakers.
And I have done three of them. Two involving space structures assembly and also the Hubble sim. My final underwater neutral buoyancy simulation was wearing a shuttle suit doing space station assembly tasks with astronaut Pete Conrad, who commanded Apollo 12 to the Moon then led the rescue of the Skylab space station. By doing such simulations the experience that you soak up in terms of operational visibility, reach limits, dexterity, workload and many other factors are the kind of things you can not learn in a briefings no matter how many you attend. In my case I had reported on satellite servicing and the Hubble development when both concepts were nothing more than paper proposals in the early 1970s. As senior space editor for Aviation Week & Space Technology at the time, I followed Hubble and overall satellite servicing in detail through the Congressional process. At the same time I was gaining extensive flight time in fighters and covering other detailed space flight operations like the Skylab rescue. I also worked extensively at the Goddard Space Flight Center with Frank Cepollina a key telescope manager and the father of satellite servicing concepts. I fear few journalists visit Goddard anymore, but it is full of cutting edge ideas. When the need arose to explore the bottom of the envelope for an end-to-end Fine Guidance Sensor EVA, Cepollina proposed that I do the job and get a unique article out it. I had already done a basic space suited NBS run and had worked out the kinks of working in a suit , so Cepi invited me to do a formal Hubble EVA simulation with Fred Sanders. First Fred and I would do our run to a 2.5 hr. checklist, then Fred and astronaut Jerry Ross would follow a few days later doing it again including the modifications we had recommended in our first run. Only three space shuttle missions had been flown to date with no EVAs, but Ross was specializing in EVA and he would eventually do several in his career. These included connecting the first U.S. and Russian elements of the International Space Station and also helping to deploy the first top secret Lacrosse imaging radar, itself equipped with Cepollina's replacement multi-mission spacecraft boxes.
A major difference between now and then was we did not make use of the robotic arm, although it was available. At the time, engineers thought a precisely aligned mechanical arm mounted on a bridge across a Spacelab pallet could provide a more efficient extraction and insertion method. The FGS would be fixed to the mechanical arm, but the astronaut would not. In the method finally adopted, however, it was the astronaut that was fixed to the robotic arm, not the FGS, that was simply ,very carefully, held by the astronaut. Our assignment was to demonstrate the mechanical arm method with the 400 lb. FGS, shaped like a baby grand piano, attached to the arm. We had a sorry looking Hubble mockup, but it was perfectly accurate up to radial instrument bay level where we would install the FGS after we extracted the sensor from the Orbital Replacement Unit Carrier (played by a Spacelab pallet). Our carrier was mounted midway in the shuttle bay forward of the telescope that was pitched down to 62 deg. just as it can be in the payload bay. We would document numerous engineering factors between the Spacelab pallet and the imaginary FGS guides that would help us slid the unit in the telescope. Our assignment was simply to reach the insertion point, then reverse the process and practice returning a failed FGS to the bay. We did the sequence in reverse order, to simplify the simulation. These initial runs were done in old Apollo A7L-B Skylab EVA suits, not the constant volume shuttle suit I would use later. We also did not use the helmet sunshades, opting instead for the "open bubble" top that would provide max visibility. I wore astronaut Jack Lousma's training suit while Sanders wore Bruce McCandless suit. Both suits were pressurized to 3 psi. Once in the pool the divers took control of us, expertly adding about 90 lb. of lead weight to make us neutrally buoyant‹essentially zero-g on all axis. Once positioned at a work site it provided an extremely realistic simulation We also had a second instrument on board, the Hubble Faint Object Camera (FOC) that served in the real Hubble until 2002. This "axial" instrument would have used the large "refrigerator" type doors for placement. Four our purposes, however, the FOC was left in the carrier to simulate interference, at that level. And it did cause trouble with our simulated portable life support system backpacks. (All of our cooling water and communications was being handled by an umbilical that the utility divers handled to maintain the integrity of the zero-g simulation. To start the transfer Sanders was positioned down on the pallet between the guidance sensor and faint object camera. Per the plan I was at the top edge of the payload bay to receive the sensor once it was attached to a transfer boom. Both of us were in foot restraints with yaw, pitch and roll settings. Foot restraint sockets are on the telescope and on the payload bay support. According to my Aviation Week description, Sanders found immediately that movement between to large instruments was constrained, something we know would be the case from "pre flight" measurements. But zero g exacerbated the situation. I came out of my foot restraints and climbed down to help. We both tried to find more comfortable pallet access positions, including approaching the pallet inverted. That too did not work: So we cited a "mark" point that before the fine guidance sensor was extracted other instruments should be removed or installed first. It has remained that way pretty much to this day, although other instruments have higher priority depending upon condition of the telescope. With me standing by aloft to control the FGS once it was free Sanders lowered the modified Skylab transfer boom affixed to the top of the pallet and connected it to the FGS. Although the Canadian remote manipulator arm was already beginning initial tests in orbit, one option for removal of FGS type instruments was this mechanical arm instead of the large robotic arm.
That was easy enough and were pleased we on our timeline with minimal diver assistance. The safety divers specifically assigned to us always prowled nearby, one with a long pipe regulator mouthpiece he was ready to shove over the suit's neck ring and into my mouth should I shatter my helmet in an accident. The 40 ft. deep water could kill you as fast as an accident in a vacuum so there was no cutting corners. One the large sensor was rotated and vertical over the pallet I maintained it steady as Sanders worked his way by me and positioned himself between me and the device. Once he was in place I aimed the boom toward him and began to manually extend it moving it toward my EV-2 partner and the opening in the side of the Hubble Space Telescope. Three engineers in scuba gear sat in the shuttle payload bay below watching what I was doing. At this point I was on of the pallet with Sanders up by the telescope. With us both in space suits the shuttle in view below and this large instrument in front, it was possible to click one's mind into painting a big blue Earth 350 mi. below. But that scene did not last long as the hardware is so large and the requirement so precise that most of the time you have a faceplate full of metal and your mind on avoiding a foulup. All of our maneuvers showed the need to provide adequate protection for the sensor head and the need for handrails in locations appropriate to movements needed. As related originally in Aviation Week I then slipped out of the foot restraint and moved toward the telescope itself. I swung my legs out over the shuttle's left radiator and maneuvered sideways down the shuttle's sill until reaching the end of the pallet closest to the telescope where I moved back into foot restraints at that end near the back of the shuttle, The difficulties encountered in simulated zero-g here were described to the simulation personnel as they were met. And it was agreed on the spot that handrails were needed to provide continuous access path for any astronauts wishing to translate in those areas. They have now been installed. After reaching the aft port area of the Spacelab roof I inserted my feet into a foot restraint off the pallet adjacent to the telescope, Sanders began extending the Skylab boom moving the FGS toward me for alignment and insertion into the telescope. During this time I frequently grabbed the well placed hand holds on the exterior of the telescope itself to gain a better angle for handling operations. I was amazed even in the water tank to be hanging on the side of the Hubble supposedly at 350 mi. high.
We were deliberately wearing bubble top suit helmets without the sunshades that provide a more Buck Rogers look but further restrict visibility. Our bubbles would give the most visibility possible, if we could not see well with those, the sun shades would make the visibility challenge even worse--so our visibility comments were logged in detail. At that point we had the FGS ready to insert in its guides. And by agreement we declared victory at that point and began to reverse the process, pretending we had just extracted an FGS and were returning it to Orbital Replacement Unit Carrier, For the removal sequence Sanders and I switched roles. As I wrote in Aviation Week he positioned himself by the telescope and I positioned myself near the forward end of the pallet to receive the instrument when Sanders backed it away from the radial bay . The movement of the FGS back to the pallet went well until above the pallet, when we attempted to precisely align it for lowering into its rack. Visibility became an unexpected problem at this point because of the space suit constraints and the black color of the guidance sensor. The boom also became stuck, and nothing we could do would free it. Time to call in Mother Earth for help. A diver came over to give it a shove, then the real problem became apparent. The sliding mechanism had bound up, And as the diver pushed against the boom it snapped. Suddenly we had a neutrally buoyant free floating fine guidance sensor instead of one attached to its insertion mechanism.. We placed a tether on it then pressed on, treating the malfunction as if it had occurred in space. We made on the spot recommendations that the whole process needed a robotic assist from the shuttle arm. That was not going to happen in our simulation, so we did the next best thing. We devised a plan to place the unit back in its rack ourselves. Sanders went down in the pallet while I stayed on top holding the FGS. And although it was hard to visually align, by using voice cues we gradually slid it into place. Once it was in place I descended to the pallet to utilize the Essex wrench to turn the long bolt that would secure it in place. After several minutes of wrench tightening we recommend this whole process be done with a power tool and that fastener indications needed to be provided to tell the astronaut crew when the mechanism was secure. We had completed our tasks within the desired 2.5 hours, the same time still allotted for it on Flight Day 8 of STS-125 when John Grunsfeld and Andrew Feustel are to do it.
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