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UPDATE # 93 - September 28, 1999 PART 1: A Quick What's up A QUICK WHAT'S UP?
I'm going to make this Update a little short so that I can get it to you before the week is over. A power outage yesterday got me a bit behind, so please don't miss tomorrow's WebCast, the first in a series surrounding the processing of the Orbiter. This promises to be an exciting behind-the-scenes adventure at the Kennedy Space Center as we find out some of what goes on in getting the Shuttles ready for flight. There are some helpful links on the event page to help you prepare yourself and your students. See you there! Linda UPCOMING EVENTS
Please be sure to visit each site before the scheduled time. Usually these events require pre-registration, and some include preparation. Remember, you can get help if you've never chatted online before. Join your chat host, Oran Cox, during one of his weekly practice sessions. http://quest.arc.nasa.gov/qchats/practice/ ->Wednesday, September 29, 1999; 10-11a.m. PDT (1-2EDT, 5-6GMT) WebCast INTRODUCTION to Space Shuttle Countdown: Landing to Launch Brandt Secosh and Mike Ciannilli bring you an introduction to the 99/00 academic year, KSC Behind the Scenes series with a special focus on shuttle processing at Kennedy Space Center. See: http://quest.arc.nasa.gov/space/events/ksc99 ->Thursday, September 30, 1999, 10 a.m. Pacific Time: Chat with Patricia Currier, payload scientist Patty works with scientists from colleges and universities around the world to help them fly biology experiments aboard the space shuttle. She helps them analyze what they want to do and figures out how to do it. In most cases, she works with scientists from scratch to determine their needs. Read Patricia Currier's profile at: http://quest.arc.nasa.gov/space/team/currier.html and see her journal below! Register on STO Chat page: http://quest.arc.nasa.gov/space/chats ->Wednesday, Oct 13, 1999, 10-11:30a.m. PDT (1-2:30 EDT, 5-6:30 GMT) Web Cast with KSC Experts. Landing, a new beginning: Brandt Secosh and Mike Ciannilli take you to the runway and introduce you to aeronautic and navigation aspects unique to landing the orbiter. Join us from http://quest.arc.nasa.gov/space/events/ksc99 To see a complete listing of NASA Quest's offerings, see the schedule of events at: http://quest.arc.nasa.gov/common/events [Editor's note: Leland is a new team member to Space Team Online. Here he describes his job, comparing it to a two-pencil test.] RELIABILITY ENGINEERING AND MISSION ASSURANCE by Leland Jackson http://quest.arc.nasa.gov/space/team/leljackson.html September 25, 1999 Interviewer: Lori Keith In my job, as a reliability engineer, we look at all the hardware that make up the space station, and assure that we can keep that hardware functioning over the life span of the station. Why is this important? Remember the last time you took a test and were told to make sure you had two sharpened pencils with erasers. There are a couple of reasons to do this, but all relate to reliability and mission assurance. I'll explain. Your mission is to take a two-hour test. You have only one opportunity to do this, so you have to do it right the first time. The test requires a #2 pencil. Because you have used a pencil before, you know that after about an hour and half of writing, it becomes too dull to use. Sometimes, even before two hours, you may press too hard and break the tip of the pencil. So what do you do to assure you can complete the test? You can either bring another pencil or bring a mechanical pencil. The first solution is called redundancy. That is, you have the exact same pencil with the same reliability, but you have enough of them to last two hours. The second solution is called increased reliability. A mechanical pencil can last longer than a regular pencil, so you only need one. On the International Space Station (ISS), we have a requirement to provide 30 days of uninterrupted microgravity every 90 days during the 20-year lifetime of the space station. To accomplish this task, ISS uses large gyroscopes to control attitude (the pointing of the station) without propulsion. ISS only needs three of these gyroscopes to meet the requirements, but it is expected that one may fail within 20 years. So, ISS will have four of them -- three plus one redundant. The more reliable things are, the less we have to carry up in replacement parts. This, of course, results in weight savings, which is ever important. An important aspect of reliability engineering is to reduce the number of what we need to take in reserve to as small as possible. We look for things that last the longest and try to use those items. For example, Mir used 20 gyroscopes to maintain microgravity. These gyroscopes were smaller then the ones for ISS, but they failed much more often. Therefore, we decided to go with a bigger but more reliable design. In the end, we saved a lot of weight. We also saved time. It's much faster to change only 4 gyroscopes rather than 20. If you remember the reliability, we expect only to change out one! Time is as important as weight with respect to space. We only have so much time (an astronaut's mission to ISS is 90 days) to complete all the things we want to do. The less time used to repair the space station, the more time the astronauts have for conducting experiments. Think back to your two-hour test. Your main task was to answer questions. You could take a regular pencil with a pencil sharpener. Now you could repair your pencil when it failed, but which is faster? Grabbing another pencil already sharpened or sharpening a pencil. The less time taken to fix your pencil, the more time you have to answer all the questions. We call this maintainability engineering. The designing of methods to reduce the amount of time something is broken or failed. Now that you know what I do, you should know a little bit more about where I work. My group, Reliability and Mission Assurance, is part of the Safety and Mission Assurance department. Although my job is primarily Mission Assurance, safety does come first! We have different levels of safety. First, and foremost, our goal is to make sure the crew survives. Second, we make sure the vehicle survives, and, third, we make sure the mission objectives survive. As far as the crew and the vehicle are concerned, if something happens that would cause either of these to perish it is considered a Critical One Failure. The Challenger explosion was a Critical One Failure. A Critical Two Failure is one where the capabilities to perform the mission scheduled to be performed have been lost. Apollo 13 had a Critical Two Failure. Although the crew and vehicle survived, the mission to the moon was lost. This is why it is important to maintain the microgravity environment on the space station as specified, or the microgravity experiments would not be able to be performed, causing a Critical Two Failure. A Critical Three Failure is any other failure that may occur that is not covered by the first two. For instance, maybe a specific communications system goes down, but data is re-routed another way losing nothing but that particular system. This would be an example of a Critical Three Failure. Critical Three Failures are common and have occurred during almost every mission. What I am working on now is a propulsion module that allows the ISS to be re-boosted from the U. S. side. The Russians currently are responsible for keeping the ISS re-boosted. But NASA always likes to have a backup plan. At this point, there are no jets or propulsion capabilities on the U.S. side, but that is being worked on. We are in the Preliminary Design Phase, going through the requirements. We know we need the module to provide propulsion, but adding it must not prevent other activities from occurring on the space station. At this point, I just need to make sure the designers are following all the mandatory ISS requirements necessary. Should the engine of the propulsion module fail, it will be jettisoned off, and another module would be brought up. It's been determined that it is more costly and it's too dangerous for the crew to do a repair of this type, so replacement is the best option. Remember that this is the redundancy to the Russian propulsion, so removing it for some time is acceptable. These concepts helped me do another task I completed last year. I was on a team to create a software simulation of the mission to Mars. The purpose was to determine how big a vehicle is needed to get to Mars using current technology (referred to as "Commercial off-the-shelf" technology or COTS) and technology known about but not yet fully developed and mass-produced (high technology items like nanotechnology). My team discovered that the current ideas for going to Mars would require a larger vehicle than what we can currently lift into space. Thus a vehicle to go to Mars is still being designed, but when it is complete, it will be able to get there and back. I hope this journal helps you to understand some of the things I work on here at NASA. STATUS OF COLUMBIA PROCESSING
Below, we provide reports on the processing of Shuttle Columbia taken from
the detailed daily reports found at the NASA Shuttle Status web site at
http://www-pao.ksc.nasa.gov/kscpao/status/status.htm
At times 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.
Columbia's ferry flight to Palmdale, CA, began Friday (September 24) for
its regularly scheduled Orbiter Maintenance Down Period (OMDP). The
orbiter, atop the modified Boeing 747 Shuttle Carrier Aircraft (SCA),
departed KSC's Shuttle Landing Facility at 12:15 p.m. en route to Whiteman
Air Force Base, MO, which is about an hour southeast of Kansas City, MO.
Columbia landed at Whiteman at about 3:30 p.m. Eastern Time and will
remain there overnight. Saturday the SCA was to depart for Palmdale, CA
and arrive
at about 1 p.m. Eastern Time.
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