|Question and Answer Board
|J. Maki from Niihama, Japan
When I was watching NASA-TV broadcasting Soyuz docking with ISS, I wondered what language do they use on the ISS? Can Russian cosmonauts speak English?
|And I think the overall answer is that they use both languages, English and Russian. Certainly when they're orbiting the Earth they have the opportunity to talk to mission controllers in Houston and they have the opportunity to talk to some folks in Moscow as well. If the Russians are communicating, more often they're talking in Russian, it's more comfortable for them. If they're talking to the JSC folks, they're speaking in English. I know from talking to some of the Russians that they do speak English, and I know that our astronauts also take Russian lessons, so I think they're probably equally versed in both languages.|
|Mark from Chicago
How does the orbiter get mounted on the flatbed orbiter transporter, and how long does it take to do this?
|When we have the orbiter inside the OPF (Orbiter Processing Facility), it's essentially jacked down, on its own wheels and tires. When it's time to finish up processing and transfer the orbiter over to the Vehicle Assembly Building (VAB), we jack it up using some floor jacks inside the OPF, and then the orbiter transporter is brought underneath the orbiter, and then the floor jacks are gently let down to allow the orbiter to interface with three points (ONSIDE THE OTS). And at that point, the main landing gear are retracted and essentially the orbiter is ready to roll over to the VAB. We do this because we used to roll the orbiter over on its own main landing gear tires, but we found out if we rolled it from the OPF to the VAB, we were picking up a lot of debris on the main landing gear tires. We had the orbiter transporters that were out in California and they became available to us so we decided it would be a better idea if when we were in the OPF, we took the main landing gear up for flight and rolled over and were ready to go by the time the orbiter got into the VAB.|
|Scott from Melbourne
Why does it take so long to get shuttles ready for a launch?
|It takes a long time, Scott, because of all the things we're doing to try and make sure that the shuttle is ready to go support the next flight. Although there are a lot of redundant systems on the orbiter, we really don't like to get on orbit and then have to take advantage of that redundancy. So we try to make sure that the orbiter is the best it can be. So all the systems - the SSMEs (Space Shuttle Main Engines) are changed out, the orbiter mechanisms for up in the payload bay, the ET doors, all the ECS Systems (Environmental Control Systems) that provide cooling and air for the astronauts and crew, all the data processing systems... they're all thoroughly checked out before flight. One of the things that also is a real time-consuming thing for shuttle processing is a need to change payloads. Because the orbiter is so flexible, and we can fly multiple types of payloads. One mission you may be flying a deployable payload and in the next mission it's possible that you're flying a payload that you're bringing back. So you need to reconfigure the payload bay. So really the flexibility of the system unfortunately adds to the time of getting it turned around.|
|Miguel from Madrid
What is MECO? Thank you very much.
|Well Miguel, MECO is an acronym -- you probably know that NASA is really big into using acronyms - and MECO is an acronym for Main Engine Cutoff. And what it actually signifies, what it means, is when the orbiter is going through ascent, and we've used all the liquid hydrogen and liquid oxygen inside of the External Tank, or used enough to get us to where we need to be in the ascent profile, the engines are shut down and the MECO call from Houston signifies that the main engines are cut off and it signals to the crew that the main engines are done for flight.|
|Emilio Pérez from Lugo, Spain
When the shuttle blasts off, why do you transfer the shuttle control to the Mission Control Center (Houston)?
|Emilio, the answer to that question is that the two centers, KSC (Kennedy Space Center) and JSC (Johnson Space Center), really have different missions. The mission of the Kennedy Space Center is to get the orbiters, SRBs (Solid Rocket Boosters) and ETs (External Tanks) ready for flight. And the mission of JSC is really to train the crew and to help the crew to manage the on-orbit operations. So KSC is really managing the countdown up until T-0 time, and after T-0 time, the JSC folks take over control and manage the flight operations. That role reverses as soon as we land and the orbiter comes to a stop and the crew is actually exiting the vehicle. JSC gives command and control of the vehicle back to to the KSC folks.|
|Emilio Pérez from Lugo, Spain
Why will mission sts-113 blast off to an altitude about 122 nautical miles, when the ISS is in orbit about 400 kilometers?
|Okay! The answer to that is actually complicated in a lot more than I can actually go into, or am prepared to go into. But the short answer is because the orbiter has to catch up to the space station and the space station is in a fixed orbit around the Earth. The way we do that is we either have to move faster or slower in order to catch up to the space station. Going in a lower orbit allows you to circumnavigate the Earth quicker so you're actually closing the gap to the space station. After T-0 they don't actually dock until launch plus three days or launch plus four days. It's just a matter of where the dynamics work in and what time we launched inside the launch window and how quickly we can get to the space station. It's a matter of trying to work out the dynamics on orbit to get to the space station when you want to.|
|Cletus from Bithlo
How long does it take the shuttle to orbit the Earth once?
|It takes approximately 90 minutes for the orbiter to go around the Earth one time, moving at 17,500 miles per hour.|
|Jon from Jacksonville
What is the purpose of the orange "bars" we sometimes see attached to the payload bay doors of the shuttle on the pad or in transit to the pad?
|I think you're probably talking about the torque tubes we install once we get the vehicle out to the pad. The payload bay doors are fairly delicate and they don't support operations in 1-G real well. So when we get to the pad we install what we call torque tubes on the outside of the payload bay doors, and the torque tubes allow the payload bay doors to stay rigid so that when we do payload bay door opening and closing after we put a payload in, we can maintain the integrity of the payload bay doors and not have to worry about damaging the doors. For horizontal operations, we actually have a STRONGVEX we install, now because the orientation of the orbiter has changed from being horizontal to vertical at the pad, when we're horizontal, we use a set of STRONG BACKs. They're a lot like the torque tubes, they're just a little bit thicker. And then we have a zero-G system that's installed in all the OPFs. So whenever we're opening and closing payload bay doors, we have a large set of counterweights that we have installed, so the doors physically go through about the same loads on Earth in 1-G that they actually always go through on orbit in zero-G.|
|Nate from Florence
I was wondering what the time frame is for post landing processing of the orbiter before heading back for "overhaul?" For example, purging of lines of any gases, post flight checks of motors, etc. Thanks, a curious jet mechanic.
|Nate, your question is a little interesting because you have to answer it probably two different ways. If we're talking about what we do after landing in order to get the orbiter back to the OPF, from what we're hooking up for purge, and how we're making sure the lines are clear before we get into the OPF. It only takes about three and a half hours from wheel stop, and depending on the payload you have, the nominal space station payloads take about three and a half hours to download the extra science that we have onboard, and get the orbiters turned around into the OPF. Now if you're talking about when we're in the OPF and how long it takes us to get the orbiter processed to get ready to fly again, that can be a matter of months.|
|Orion from Ninrveh
What are some of the activities that take place during turnaround, and can you give me a thorough explanation of the activities?
|I can certainly give you a taste of what some of the activities are. Certainly when we get back to the OPF we need to take care of the main engines and the main engines are changed out because they have to go back for some fairly detailed inspection at the main engine shop here at Kennedy Space Center. So the engines are one of the items that we take all three of the engines off, and we normally have another set of engines that are ready to get installed again. We also do checkout, as I mentioned before our (BODY) orbiter components like the orbiter payload bay doors, the ET doors are checked out, the wheels and tires are inspected and the main landing gear tires are changed out and those landing gear tires if they're acceptable are flown again. All the DPS folks that handle data processing on the orbiter have checkouts to go do, the folks that manage the OMS RCS system (Orbital Maneuvering System - Reaction Control System) have to check out those systems, so every individual system component on the orbiter gets a thorough checkout before launch.|
|Jeremy Hartings from New Orleans, Louisiana
What are the windows in the space shuttle made out of?
|The windows on the space shuttle are actually made out of aluminum silicate glass and fused silica glass. The orbiter windows are actually three different panes, there's an interior pressure pane because the pressure inside the orbiter is a lot higher than it is in the vacuum of space. We also have an optical pane that's installed in the middle that's about three and a half inches thick and on the outside, there's a thermal pane that protects the inside of the cockpit from the high heats of ascent and reentry. There are six forward-looking windows, three on the CDR (Commander) side and three on the PLT (Pilot) side. There are two overhead windows that the crew out of especially when docking to the space station they're using those windows to watch the orbiter approach the space station. And then there are two windows on the aft that look into the payload bay, and depending on our hatch configuration on the inside, there can be anywhere from one to two additional windows, they're small holes that are installed inside the hatches so you can look through hatch windows. And the side hatch, the emergency egress hatch, has a small hatch window as well. They're all made of the same materials. The forward windows -- the ones that the crew actually uses for ascent and entry -- are the ones we have to take really good care of in order to maintain the optical quality of them.|
|James from Millersport
What kind of fuel is used in the RCS and OMS Systems?
|The RCS and OMS systems use monomethyl hydrazine and nitrogen tetroxide. It's a system that doesn't require oxygen to be combustible, so that you can mix those two components in the proper ratios and end up being able to maneuver the orbiter on orbit.|
|Julia from Canberra
What materials are used to protect shuttles during re-entry?
|Julia, we use a number of different materials to protect the orbiter from re-entry heat, and for ascent heating as well. If you look at the nose cap of the orbiter, the very front of the orbiter, and what coating is on the wings, it's a reinforced carbon-carbon material. If you looked on the bottom of the orbiter it's covered with black tiles which are actually a silicate made of glass, and if you looked on the top of the wings we actually have a few silica blankets and those cover the payload bay doors as well. So depending on what area of the orbiter we're trying to protect, and what temperatures that area of the orbiter is exposed to, we have a certain prescribed type of thermal protection system that we keep applied to those areas.|
|Jeff from Hopkinsville
The tiles and thermal blankets are glued to the orbiter, right? The glue used has to be really strong to stand up to the aero pressures that are put on the vehicle during flight. So how do you remove a damaged tile or thermal blanket when it is damaged and must be replaced?
|Well Jeff, if we come back from orbit or from orbiter processing operations and have to to go in and replace a tile, if it's one of the hard tile that's on the bottom of the orbiter, one of the white tile, we normally have to destructively remove it. You have to use a little pick and begin chipping through the hard outer coating of the tile and that exposes the very soft inner portion of the tile and you can just kind of chip it out of the cavity, and then you've got a strain isolation pad that the actual tile rides on, since it doesn't interface directly with the orbiter, metal structure, and you can just scrape that off with a non-metallic scraper. And if we're talking about one of the blankets installed on the wing or up on top of the payload bay doors, it's a simple matter of getting a non-metallic scraper in there and opening up a little hole where you can start scraping out and just pull back the blanket. And you just scrape it off and prepare the surface and you're ready to go bond another tile in place. We have tiles and blankets because originally when the orbiters came in they had a lot more tiles, somewhere around 33,000 or 34,000 tiles. Right now we have about 23,000 tiles. What we did was, through processing, we realized that there were areas on the orbiter where you could actually tolerate some lower heat, like on top of the payload bay doors and up on top of the wings. The blankets cover a larger area, so there's not so much maintenance associated with them, and actually they're lighter and easier to work with than the tile, and they take a lot more abuse than the tiles do as well.|
|Jim from Grand Junction
What are the actual number of TPS heat shield tiles used on each orbiter today?
|About 23,000, and certainly every orbiter differs a little bit, but it's somewhere around 23,000 tiles.|
|Emilio Pérez from Lugo, Spain
How much Power does the two SRBs have? Thanks.
|The solid rocket boosters have about 2.6 million pounds of thrust apiece. They weight about a million pounds in the propellant side and produce about 2.6 million pounds of thrust. The amount of thrust actually varies, we're using the solid rocket motors and you cannot go in and change the propellant in real time, or you can't turn the thrust up or down in real time, and when the Thiokol folks in Utah cast the motors for us, they actually cast the forward grain in a little different shape, it actually has a star pattern on the inside. So at T-0 when we send the command for the solid rocket motor igniter to ignite the rest of the grain, the star pattern enables the solid rocket motors to burn a little hotter and provide a little more thrust in the beginning of the countdown and in order to get you off the pad and then as we're going through ascent, we may want to decrease the thrust when we're going through Max Q, the grain is also tailor-made to take that into account. And then as you're going up the hill it becomes a steady profile and then you just burn out your propellant and essentially get ready to have SRB separation.|
|James Kelley from Cananduagia
How long does it take to retrieve the solid rocket boosters and get them ready for another launch?
|James, it takes approximately two days if we're looking at from the time the boosters enter the water until the time they get back to Hangar AF. It takes about two days for the two retrieval ships to go back and retrieve each booster, left-hand and right-hand. Once they're back to Hangar AF, the boosters are taken out of the water and put onto modified rail cars and are able to turn the boosters and they're given a thorough post-flight inspection. After post-flight inspection is done and everyone is convinced and ready to give permission to begin separating the segments. The segments are separated individually at Hangar AF, the forward skirt is demated and the aft skirt is demated as well, and the components are shipped out to respective sites. The forward skirts and the aft skirts stay here where we process them here at Kennedy Space Center with a subcontractor, and the actual solid rocket motor casings for them are sent back Thiokol on rail cars. Now once they get back, the Thiokol folks have to clean them, reinspect them and go back and refill the solid rocket motors. So it can be anywhere from six months to years before we see that same segment come back to KSC and be ready for use again.|
|John L. from Santa Barbara
What is the life expectancy of #1 or #2 crawler?
|John, we started using the crawlers in the 1960s. And we've had to keep using the crawlers, when we went from Apollo to the shuttle. And the plan is to keep using the crawlers. We take good care of them and they're in great shape, and we constantly work to make them better and make sure that they're supporting all the way until we move on to the next phase of the program.|
|Michelle from Augusta
What is the process for submitting and taking a photo?
|Michelle, the first part of your question is, we get more than 100 percent thrust out of the engines when we say we're up at 100 percent that's at the thrust at sea level. And as the engines go through the atmosphere and the atmosphere becomes thinner, the main engines actually get more efficient, so eventually you can achieve more than 100 percent thrust because of what you're doing in the ascent profile. And we actually get to 104 percent of rated thrust. And for the second part of your question, the astronauts feel somewhere around three G's when they're in the ascent profile, and somewhere around three G's when they're coming back for descent is about the worst G case that they feel.|