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UPDATE # 36 - January 31, 1998 PART 1: The Great Habitat Debate THE GREAT HABITAT DEBATE
In April, NASA flies STS-90 to study brains in space. Some of those brains belong to animals, and the problem of building a good space-qualified animal house is the focus of "THE GREAT HABITAT DEBATE." For a few days to a few weeks (you decide), kids learn about animal needs and microgravity environments. Next they design an animal cage to meet given constraints. Then they publish their designs online. Throughout, a vigorous student discussion takes place: A recent thread talked about the challenges and opportunities inherent in baby space suits for mice. Several times over the next month, NASA experts are available in chats to brainstorm ideas and provide live Q&A. Soon a more thorough review will be done of all student submissions. One student proposed gluing carrots to the floor to avoid food float-away. Another student designed this zero-g waste disposal system: ...a tube going to the hamster tank. The tube would have to be very small so solid and liquid waste could get through. The force of the air wouldn't suck the hamster to it. It could only suck things lighter than the hamster, and the tube suction would always be there to catch the waste from the hamster. At first it sounds OK, but then we found out the student intended the tube to penetrate all Shuttle walls into the vacuum of space. I'm not sure if NASA's safety engineers will go for that approach. Anyway, there is great learning going on, with biology, space and problem-solving scenarios. Kids are having a blast (they are allowed to say turd in class). And it can all be done in a short period of time anytime over the next few weeks. So if it works for you, please consider joining us on Quest for THE GREAT HABITAT DEBATE http://quest.arc.nasa.gov/neuron/events/habitat/ SPACE STATION VIDEOCONFERENCES
As mentioned in STO #34, the end of February will bring two live videoconferences with the key NASA people responsible for the Space Station. On February 19 the event is geared for students in grades 5-12. On February 26, the program is geared for working professionals and may also interest college students. Although the best broadcast quality will be obtained via satellite download, another option is to view the audio/video over the Internet. Opportunities to interact with the program via Internet chat will be provided. For more details, see this Learning Technologies Channel page: http://quest.arc.nasa.gov/ltc/sto/info.html STS-89 COMPLETES SUCCESSFUL MISSION
We couldn't let the STS-89 mission go by unmentioned. After an on-time launch on January 22, Endeavour quickly rendezvoused with Space Station Mir to deliver astronaut Andy Thomas. As well, the mission brought home his predecessor Dave Wolf, who had spent 128 days in orbit. The shuttle Endeavour landed at the Kennedy Space Center at 5:35 p.m. Eastern Standard Time on January 31. Congratulations to the entire team that produced a safe and successful shuttle mission! [Editor's note: Andy is a computer engineer who works on the ground support equipment at Kennedy Space Center. Andy develops automated systems that control the ground support equipment. Some of these systems focus on data acquisition; they use sensors to take measurements and display them to an operator. Other systems are automated machines (robots) that move to perform tasks.] SPECIAL EQUIPMENT FOR STACKING THE BOOSTERS
Andy Bradley http://quest.arc.nasa.gov/space/team/bradley.html January 29, l998 The space shuttle has two Solid Rocket Boosters (SRBs) to help launch it into orbit. Each SRB is composed of four segments, called Solid Rocket Motors (SRMs). The SRMs arrive at Kennedy Space Center (KSC) separately, and must be "stacked" in the Vehicle Assembly Building (VAB). After the January 28, 1986, Challenger mission, the SRM stacking procedure came under intense scrutiny for safety purposes. NASA developed several data acquisition systems to monitor and, if possible, record the stacking process. One of these systems is the "Lifting Beam Load Panel." A large metal fixture called the "lifting beam" is connected by cables to a huge crane, hoisted above the segment, and attached to it at four points. The crane then lifts the entire package over another SRM, and slowly lowers until the two segments are "mated." The lifting beam load panel measures and displays (but doesn't record) the weight of the suspended segment at each of the four points. Contrary to what you may believe, the SRMs aren't perfectly cylindrical. On a very small scale, they can be somewhat peanut shaped. If the two segments being mated don't match, the joint may leak, which could spell disaster for the shuttle. Therefore, the lifting beam was made to allow each major leg to be adjusted to lift more or less weight. By adjusting the loads, the SRM shape can be changed to match that of its partner. Another system is the "Temposonics Panel," named after the company that built the sensors. When the two segments that are being mated are close together (4 or 5 inches apart), four Temposonics sensors that can measure distance are connected to them. The sensors are then connected to a computer system that displays the information to the operator. With this data, the operator can tell how far apart the segments are at the four locations, how level the segments are in relation to one another, and over time, how fast the upper segment is being lowered. Each measurement can be recorded for later use, but the data ends up in anywhere from 75 to 200 different data files! In addition, the information is displayed as lines of text across a small monochrome computer monitor. You can imagine how tiring it must be to view that information during the stacking process, which takes several hours. Both of these two data acquisition systems are over ten years old (that's a lot in computer years). They fail frequently and contain components that are nearly impossible to replace. I'm working on a new system called SSET that will fix these problems. The SSET project takes the function of each of the two systems and combines them into one. Because of the available equipment and software tools, many enhancements are included. For instance, the SSET display is a large, high-resolution color monitor, which presents the data in a fashion that makes it easy to see what's really happening. The software maintains a log file of all the important events, such as the health of the hardware, and each of the operator inputs, making troubleshooting easier. All the measurements are recorded into a single measurement file. Roughly an hour of previously recorded data can be reviewed while the system is operating. The data can even be printed on-the-spot with the built in color printer. Another advance that SSET has is its use of Commercial Off The Shelf (COTS) components. If a piece fails, a new one can be purchased and installed in a relatively short time. (Actually, we keep spares on hand, making the "down time" even shorter.) In addition, those COTS components cost far less than custom built ones. SSET is scheduled to begin operation in June 1998. A follow-on project is in the works that will replace the aging Temposonics sensors with advanced 3-D position sensors. These new devices will help solve some problems such as aligning the centers of the two SRMs, and twisting, or "clocking" the segments so the pin holes used to fasten them are aligned. [Editor's note: Stephanie is an experiment integration engineer. She interprets electrical schematics and writes test procedures to test all the experiment power cables to make sure that they were built correctly. This is the last installment of a series in which Stephanie has shared her experience with CHeX, an experiment that flew recently in space. CHeX involves studying helium at very specific temperatures. Last time, Stephanie was studying how other experiments effected CHeX results.] CHEX WRAPS UP A SUCCESSFUL MISSION
Stephanie Stilson http://quest.arc.nasa.gov/space/team/stilson.html November 30, 1997 (Flight Day 12) High resolution and high temperature scans continue. The resolution of the completed scans ranges from 20 nanodegrees down to 2 nanodegrees thanks to the excellent quality of microgravity we've had so far. The high temperature scans have begun to reveal the small contribution on the finite size effect called "surface specific heat." CHeX was designed to magnify this effect by its large surface area and the team awaits with enthusiasm high quality data in this region. The decision was made not to redeploy SPARTAN which is a relief to the CHeX team. In discussion now is whether a second Extra Vehicular Activity (EVA) will be performed. This should not have any effect on CHeX since if it is performed, it would take place after CHeX runs out of helium. December 1, 1997 (Flight Day 13) Today a long high temperature scan was completed and high resolution scans were restarted at the beginning of the crew sleep period. CHeX has exceeded the operational lifetime achieved by its predecessor, the Lambda Point Experiment (LPE) which flew as a part of USMP-1 in October 1992. The experiment's operational lifetime is set by the time it takes for the -456 degree Fahrenheit liquid helium launched with the experiment to evaporate away. Current estimates have the evaporation rate reduced to less than three tenths of a teaspoon every minute. The enhancement in orbital lifetime has been necessary to take full advantage of the available thermometer resolution. This has in turn allowed CHeX to achieve the highest accuracy heat capacity measurements ever attempted in space. December 2, 1997 (Flight Day 14) While I was off-shift, CHeX ran out of helium. Although the team was sad to have our mission end, the results that we have gathered will be very useful. When I reported on station, CHeX had already been deactivated so there wasn't much left for me to do. I helped the team box up some documentation, and then I headed to the airport. The experiment that I am working with on the next Spacelab mission, the Vestibular Function Experiment Unit (VFEU), is testing on December 4. So I am eager to get back to KSC to continue preparing. That's another story for another day!!! STATUS OF COLUMBIA PROCESSING
Below, we'll provide some details about the postflight work being done after STS-87 and the subsequent processing of Columbia as it prepares to fly again as STS-90. These reports will contain jargon and unfamiliar terms; our intent is not to confuse you, but to provide a glimpse at all the steps involved. Detailed daily reports about Columbia's processing can be found at the NASA Shuttle Status Web site at http://www-pao.ksc.nasa.gov/kscpao/status/status.htm Since the last updates-sto message, workers completed tunnel adapter installation and functional tests of the external tank umbilical doors. Columbia's aft flight deck continues to undergo reconfiguration. Servicing of the ammonia boilers is complete to date and mid-body close-outs continue. Gaseous nitrogen servicing of the water spray boiler is complete. Work to remove residual reactants from Columbia's orbital maneuvering system continue. A leak may exist on one of the manifolds and workers are attempting to isolate that system to complete the inerting process. As a result, installation of the main engines and installation of Neurolab into the orbiter has been delayed several days. With removal of residual reactants from Columbia's right-hand orbital maneuvering system (OMS) pod complete, technicians replaced three thrusters and began thruster leak checks. Payload bay flood lights No. 1, 3 and 5 have been replaced and tested. STS-90 SCHEDULED OPERATIONAL MILESTONES (dates are target only): - Payload premate test begins (Feb. 3) - Shuttle main engine installation complete (Feb. 4) - Payload installed into orbiter (Feb. 9) - Shuttle main engine heat shield installation begins (Feb. 11) - Payload interface verification test (Feb. 12)
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