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UPDATE # 14 - June 15, 1997 PART 1: A feast for your eye A FEAST FOR YOUR EYES
A big pat on the back to the fifth grade students in Bob Townsend's class. They've created some great drawings of the space shuttle and they've shared it with us. Please look at: http://quest.arc.nasa.gov/space/kids/work.html If you have nice student work that you'd like to publish on NASA's web, please see: http://quest.arc.nasa.gov/space/events/posting.html THE SURVEY IS OUT AND THANKS
If you've been part of this list for more then two weeks, you should have already received an email survey. We've gotten a great response so far. THANKS SO MUCH! We are learning a ton from your wonderful suggestions and really appreciate the detailed stories with your thoughts. If you haven't yet returned the survey, please do so soon. If you are too busy to send stories or notes, please just fill out the multiple choice questions. A strong response rate will really help us keep this project going into the future. Thank you again for your help here. WEBCHATS RESTARTING IN JULY
You may or may not know about the series of WebChats we had in April and May. During these one-hour sessions, NASA people appeared live online. You could type brief thoughts and have the experts respond right away to your questions. We plan another series beginning in early July. For more details, and for the complete schedule, please visit: http://quest.arc.nasa.gov/space/events/interact.html RADIO CONTACT WITH THE SHUTTLE ASTRONAUTS
A program called SAREX lets schools use ham radios to communicate with the Space Shuttle astronauts. A class gets a little time to radio questions to the shuttle and then listen to the responses live. This is a popular program and the waiting list is about 4 years. Back in 1993, Crittenden Middle School (Mt. View, CA) applied to SAREX. Finally they were selected to participate in the STS-83 mission. When that mission was shortened, they were rescheduled on STS-94. Their radio time is presently scheduled for July 4 when they'll have nine minutes with James D. Halsell Jr. (Mission Commander). Mr. Scott Coletti, the technology teacher at Crittenden, is a big fan of the Internet and he wants to share the SAREX experience online. So he is willing to take email questions from you and consider them for broadcast to the shuttle crew. If you are interested, think of some good questions and email them to this address: sarex-sto@quest.arc.nasa.gov. To be considered, the questions must be mailed in by June 27. Scott and his students will select one or two questions and radio it to the astronauts orbiting in the space shuttle. Once they have the answer, you'll be emailed the reply. The Crittenden crew will select questions based on the following criteria: * Is the question one that gets the CrittKids interested in the answer? * Is the question generally interesting to middle school students? * Does the question illustrate points about the specific STS-94 mission? Here are some more tips on creating a good question: Take a look at http://shuttle.nasa.gov to see how James D. Halsell Jr got from middle school to where you will find him on July 4th. The wonder of zero gravity is part of the science being done on board Columbia this mission. One test will study how a flame grows after being started. Questions? Well, do your homework and send in those well formed questions soon. [Editor's note: Bob is a mathematician/computer programmer. The kind of math he knows about is extremely useful for making some shuttle and control center computers be able to do some simple, common sense reasoning that we humans can do without even thinking about it. Also, Bob is one of the main JSC organizers of the Shuttle Team Online project.] A NEEDLE IN A HAYSTACK PROBLEM
Robert Shelton http://quest.arc.nasa.gov/space/team/shelton.html April 23, l997 Hi, it's been some time since I've had a chance to write. I did finally read all the files necessary to support the code review, and we got through a sizable chunk of the program, but it was really boring and technical, so I'm not going to say anything else about it today. We do have a more interesting problem to work on right now. The shuttle has motors (not rocket motors, but motors like you'd find in your car) to run heavy-duty mechanical systems during assent and reentry. These "motors" are called Auxiliary Power Units or APUs. The APU fuel is kept in a pressurized tank, and the pressure is watched *VERY* carefully by the flight controllers to monitor leakage. All pressurized systems leak at least a little, and the pressure fluctuates up and down with day and night, just like the air pressure in your tires, so the controllers have to distinguish normal variations and insignificant leakage from what could be a problem. Our challenge is that the normal changes in the pressure over a short time are larger than the changes you'd see, even if there was a leak. This leaves us with a "needle in a haystack" problem of sorting out "signal" -- the leak, from "noise" all the normal changes in the system + the random errors that show up in the sensors -- that's right, the electronics that measure the pressure are not perfect either. They round off the true pressure to a value that the electronics can understand. This is called a "quantization" problem because the sensors can only report readings that are whole multiples of some fixed value -- the "quantum", think of it as rounding off the pressure to the nearest pound. So, how do we solve this problem? Our first approach is to watch the flight controllers who are *VERY* good at spotting trends in the data. We observe the tricks that humans use, and where possible, program our machines to do the same thing. We also try to use some mathematical tricks to remove noise from the signal. Next time I'll tell you what we tried, but in the mean time, if you have any ideas, pass them along. [Editor's note: Rick is a design engineer who works on Ground Support Equipment that helps get the shuttle ready to fly. Rick often has several projects at once. Rick has an interesting background which started in the military as a technician. At one point he tracked manatees with SONAR. Eventually with hard work he earned an engineering degree.] MACHINES THAT SNIFF THE AIR FOR HYDROGEN
Frederick W. Adams http://quest.arc.nasa.gov/space/team/adams.html May 19, l997 In my job, I work on a variety of projects at once. Last time I wrote about an automatic system for detecting problems with the Shuttle's windows. I am also working on the development o IHUMS, the Interim Hydrogen Umbilical Mass Spectrometer, an integrated system that looks for one part per million concentrations of hydrogen into either helium or nitrogen or air backgrounds. It was basically a takeoff from an earlier commercial system (B/U HGDS) that was currently used in the mobile launcher for the same purposes. The interim system (IHUMS) was developed in my lab and used at the pad during the STS-35/38 leak scenarios. Leak testing for STS-35/38 involved locating and measuring the amount of liquid hydrogen leakage from Shuttle Flight hardware utilizing catalytic and mass spectrometer-based techniques. Work involved taking a commercial mass spectrometer on temporary travel to Downey California and Huntsville, Alabama (Marshall Space Flight Center). After the leak testing was complete we started on designing a system known as the Advanced HGDS for the US Air Force. They wanted to automate the entire process of hydrogen leak detection and needed a computerized, automated system that performed the same functions as HGDS did at KSC for Shuttle. MRMS, a miniature, ruggedized mass spectrometer was intended to be a flight prototype that would extend the capability for utilizing a mass spectrometer during powered flight, giving faster access to leak data during the time frame when the main engines were operating at flight pressures, and in the high vibration powered flight environment. STATUS OF STS-94 PROCESSING
Below and in the future, we'll provide some details about the post flight work being done after STS-83 and the subsequent processing of Columbia as it gets ready to fly again as STS-94. 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, Columbia was mated to the external tank and solid rocket boosters. This operation took place in the Vehicle Assembly Building. After the Shuttle Interface Test was completed, Columbia left the Vehicle Assembly Building at about 2:45 a.m. on June 11 and arrived at pad 39A at about 8 a.m. Pad validation efforts concluded on June 12 and auxiliary power unit hot fire testing was successfully completed. The Rotating Service Structure was placed around Columbia at about 9:30 a.m. on June 12. NASA's plan to eventually use a super lightweight external fuel tank requires modification to an orbiter's tail service mast. Columbia's tail service mast underwent retraction tests to assist engineers in that effort. Additional thermal protection tiles were removed from the orbiter's forward reaction control system. More than 30 suspect tiles have been removed because of cracks seen during recent inspections. Of the tiles removed on Columbia, only 7 were cracked. Evaluations of the FRCS tiles on the other orbiters have resulted in the removal of several tiles from orbiters Discovery and Atlantis. Stronger tiles will replace those that were removed from each orbiter. The stronger tiles will better sustain the loads associated with thruster removal procedures and on orbit thruster firing, factors that contribute to tile cracking. Shuttle managers have developed a success-oriented plan to replace about 36 tiles on Columbia's forward reaction control system, located on the nose of the orbiter. The tile work is being performed at the pad and is scheduled to be complete in time for the July 1 launch date. The main engine flight readiness test was successfully completed. Also, some repair work to wiring in avionics bay No. 4 was resumed. STS-94 SCHEDULED OPERATIONAL MILESTONES (dates are target only): - Helium Signature Test (June 17) - Hypergolic propellant load begins (June 19) - Flight Readiness Review (June 19)
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