The launch window is small because ISS has to be essentially lined up in orbit in a tight tolerance (called the phase angle) to rendezvous this quickly. Usually the Soyuz plays "catch up" over 2 days by flying lower (and faster) than ISS. You can control the closing rate between the vehicles by altering the altitude difference between them, which allows you to make up differences in the orbits between the vehicles. Those differences are usually just fallouts of other things, like having uncertainty in launch dates, getting the altitude just right for other vehicles (there is about a rendezvous a month at ISS), etc. It's not because Soyuz is slow, it's because spreading the rendezvous over 2 days gives you some targeting flexibility.
You have less margin to work with when you are trying to get there in 4 orbits instead of 34 orbits. Hitting that target with both ISS and Soyuz is hard but it's more about ground targeting than performance of the launch vehicle. The launch vehicle didn't give any extra oomph to get there faster, the ground essentially had the vehicle phasing in a tight tolerance at launch. They also sped up some of the tracking that was being done and turning that around into updated burns for the next orbit instead of coasting to a set of burns the next day, which was a bunch of work for the ground in a short period of time.
The Russians that devised this actually published it - it's an interesting read if you have access to the journal or want to spend $32:
About 10 years ago I was at the VAB when all 4 orbiters were at KSC. There are only 3 bays in the Orbiter Processing Facility, and at the time the fourth shuttle was usually in Palmdale on a maintenance rotation. On the rare occasion where all four were at KSC, one had to be left in a corner somewhere waiting for it's turn in an OPF bay.
So, as I walked into the VAB (which is essentially a 50 story open bay, with a lot of open space) off on the left is Discovery, engines out, parked in the corner with a huge tarp suspended over it to protect it from stuff falling from above. It looked a little forlorn over there - literally "parked with a sheet over it". It was sort of surreal, because it was like seeing someones old project car in the corner of their garage, except it was an orbiter.
Anyways, even in this sort of storage you wouldn't be able to fly it again. The engineering and manufacturing infrastructure which supports the shuttle has been dissolved or is in the process of being dissolved. The physical orbiter was only a small piece of that infrastructure, which ran the gamut of things from trajectory analysts, simulators, manufacturing facilities for tanks, a control center staffed by trained personnel, etc. etc. It's not like pulling an aircraft out of storage, restoring it, and flying it. The space industry and space systems are still very specialized and rely on significant amounts of engineering, specialized equipment, and specialized knowledge on the part of the engineers and technicians supporting a particular system. Hopefully that will change soon.
I'd take it more as the white room crew making a patriotic statement than a religious reference. In many of the employees, there is a pretty significant sense of national service, both on the part of the government and contractor employees. I would say the majority of employees (at least the ones I worked with, who were mainly engineers) were primarily motivated by things other than a paycheck, which in most cases was smaller than a similar private sector position.
One interesting thing about the "God" reference - I'm not particularly religious, but to some it was not all about the science and engineering when there are people onboard. I've worked manned and unmanned launches. When there are people you actually know and work with daily onboard, it's got a whole different sense about it - and it would cause religious feelings to well up in some people who ordinarily were fairly agnostic.
She didn't make it up, she quoted a senior official - the Boeing payload manager at KSC (Mike Kinslow). This is the first public mention that I've seen, but it is in the planning stages (as a recent addition, which is why this is the first public mention of it).
So what DO you do when the battery charger bursts into flames on orbit?
I'll reinforce your point here. Knowing something about the fire response strategy on ISS you do the following:
1) If you actually are lucky enough to witness the charger burst into flames, remove the power from it, hit the fire alarm, put on a mask, and expend a CO2 based fire extinguisher on it. The mask keeps you from asphyxiating yourself with the extinguisher.
2) If you don't physically see what happens (which is most likely, ISS is big and some modules may go unattended for hours) - the combustion products will trip off a cabin smoke detector in the module. That will stop ventilation inside the module and ring the alarm. In most cases, this will put out a fire in zero g - fires tend to smother themselves without gravity to force convection currents.
Meanwhile, not having any knowledge other than a smoke alarm from a module, the crew will converge in a safe haven in the vehicle away from the fire. Two (of the 6) may go forward to investigate with masks, fire extinguishers, and a hand held device to detect combustion products (mainly so they know if they are entering a lethal pocket of CO or other gases). Hopefully the module isn't a total fog of combustion products - if it is, the crew is likely to isolate it and leave it. If you don't know what the fire source is (because you can't see it), it may well end up that the entire module ends up getting powered down to ensure an electrical fire isn't being fed. This of course has some pretty serious ramifications as well - shutting down power to a module is not a simple event to reverse (since all the computers, cooling, lights, etc. go down with it). It's likely that collateral damage to a module's systems would happen if that were done.
Even if you do understand what happened and know it's out, the harmful gases from burning plastic aren't going to just go away on their own, they have to be scrubbed out with deployed fans and special canisters. It would take weeks to clean up.
Fighting a fire in a closed environment is very different than something you would do in your home. In zero gravity, most of the control is by prevention - don't use flammable materials, stop ventilation on a detected fire so it doesn't spread, don't use things that generate poison air when they burn, etc. Even a minor fire that many of us have encountered at one time or another (smoked electronics, plastic bag on fire, etc.) would be an extremely serious event in space. That's why so much time is spent making sure equipment conforms with fire prevention standards.
I don't think the cost per kg of cargo is a driving factor on this decision. The US government has a vested interest in supporting both SpaceX and Orbital on the COTS contract. If successful the vehicle SpaceX is developing will provide a domestically produced launch vehicle that has shows some promise in having a lot of launch flexibility and much cheaper rides to orbit.
Additionally, if SpaceX is successful it will provide some negotiation power in getting upmass to ISS (the rides get more expensive when Progress is the only game in town) and will also provide some competition on government contracts to the United Launch Alliance consortium of Boeing and Lockheed Martin.
We actually had an interesting situation where I work (spacecraft operations). We had a senior aerospace engineer depart after 15 years to become an airline pilot, of all things (decided to turn a hobby into a job).
About a year later, he came back part time because the routes he flew left him with large blocks of free time at irregular periods during the month, and he was getting bored (because before his "hobby" was flying....and he stopped doing that on his days off!).
It was a win-win situation. He'd give us 40-60 hours a month of hourly work when it was convenient for him. We kept his hopper full of things like documentation, training, and other stuff that most senior guys consider dreg work. Even though he now has enough seniority to avoid pilot furloughs, he'll volunteer to drop his flight hours if the airline needs him to. He just increases his hours with us (and he's so good, we'll take whatever he gives us up to full time).
Since he's not interested in advancing up the ladder, he really does a great job on this low-visibility stuff that really helps an organization run well if it's done right.
I understand your point, however this particular software is basically a system for tracking vehicle "funnies" on the ground, it's not something that is in the loop of the vehicle flight software or something used to make critical decisions. The old system is pretty dated and unwieldy to use (I've used it, I work for NASA). We're obligated to try out cheaper alternatives to custom code to see if it works for us without compromising what we are trying to do.
Sometimes it does work for us - the Mission Control Center workstations and the onboard command and control laptops on the Space Station were all recently converted to Red Hat. It is in many ways better than the old proprietary unix solutions because with the source it's easy to do our own mods to the software. We still test the daylights out of it since that is critical software, but it's a lot easier to support since we have the source code and can do our own bug in-house bug investigations, patch it, or rip out things we don't want/need.
I guess I'll take exception to calling astronauts the "annointed elite". Read through the biographies of the current crop of astronauts, and you'll see a pretty broad demographic of military officers, researchers, doctors, and even a teacher. Almost all came from a middle class background and got where they are through hard work.
The astronaut selection process is completely merit based, albeit extremely selective (since there's way more applicants than openings).
I'd be interested in what your propose NASA do to put "normal citizens" into space. Right now NASA and a couple of other government agencies are SpaceX's main funding source, and SpaceX probably has the best chance of coming up with a private ride to orbit for normal (albeit rather rich) citizens to go to space based on this work.
One Soyuz couldn't get there but two, flown serially, certainly could.
I think the extra trips was referring to the number of crew members onboard the orbiter (since Soyuz only has three seats, and really you do need two people to fly it).
I don't understand how flying Soyuz "serially" is going to get it to 28.5, if you could elaborate. The amount of propellant to do that kind of plane change is enormous, even the shuttle (which was designed do a lot of maneuvering) is only capable of doing a couple of degrees.
The cost is actually far less than you believe. The "rescue" shuttle is simply the vehicle for the next flight (minus payload). It's already going through the normal processing flow to ready it for its planned launch in November. The additional cost to protect for a rescue mission is in the low millions.
I was wondering though does the ISS have more than one place to dock a shuttle? Or do they have to somehow undock the damaged craft after the crew disembark and then dock the rescue craft? Or does the whole rescue process happen while both craft are undocked and the crew do a cool space dive between shuttles?
The damaged orbiter is undocked first by remote control from the ground. The crew needs to install a cable to allow the command to open the docking system hooks (which is normally a push button the crew performs on the aft flight deck) to be sent from the ground.
Pay the Russians to get a Soyuz ready? Although it might take two trips...
The orbital inclination of Hubble is 28.5 degrees (essentially due east from Kennedy Space Center). The Soyuz pad at Baikonur is too far north to reach that inclination without doing a plane change, which takes more propellant than Soyuz carries.
The interesting thing is that in order to get such an orbit, it has to pass over other countries. Will Google take footage of other countries? If so, will it use that footage? That would probably require some intense international negotiations.
Actually, it will not. I'm not sure if it's codified anywhere in international law or just by historical precedent, but a nation's airspace does not extend into space. A satellite can legally take photos of anything it can see, and there's little a country can do about it except hide things under cover or shoot it down (which likely would be considered an act of war).
Some countries (like the US) can exert control in limited ways by restricting operations if the imaging company does business in the country, but that's it.
Google has quite detailed satellite photos of Pyongyang, North Korea - I'm sure they didn't really agree to that.
The calculated miss distance was about a mile, but there was uncertainty in that miss distance such that there was a 1 in 72 chance it wouldn't miss the ISS, but instead hit it directly.
To answer your question (at a high level), the sensors and models that are used to track and predict the debris locations have associated mathematical models that can put a number on the uncertainty of where that debris is. The uncertainty takes into account things like how many radar obs were made, the inherent accuracy of the radar, uncertainties in atmospheric drag, etc. You can never know exactly where an object is, only an approximation of the current and future location and a mathematical confidence in that estimate. In this case that confidence was sufficiently low (and the risk of impact high enough) that a collision avoidance maneuver was executed.
One of the things that makes airline accidents so deadly isn't necessarily the altitude, but the speed and the fact that these things are carrying so much damn fuel. I wonder which has more energy, the envelope of the Hindenburg or your average passenger jet fuel tank...
Interesting question. I did some quick googling and math. I wasn't particularly careful, so corrections are welcome.
The Hindenburg had a gas volume of 200,000 m^3, at 0.089 kg/m^3 standard density of hydrogen gas, that is a total hydrogen load of 17,800 kg. Hydrogen has a high energy density of 143 MJ/kg.
A fairly heavily loaded 747 will be carrying 136,000 kg of Jet-A at 43 MJ/kg.
So, the 747 has more than twice the energy onboard, although smaller jets would be rougly equal, all depending on the fuel load. I also did not include the diesel onboard the Hindenburg (or its rather flammable aluminum paint).
One significant difference between hydrogen and Jet-A burning is that the hydrogen is going to rise once the gas bags rupture and not hang around on the ground like Jet-A.
To change the orbit to intersect the sun, a tremendous amount of velocity would need to be removed from the current orbit. It would take more propellant to get it to the sun than it took to launch it from the earth in the first place.
It's actually quite difficult to "hit the sun", the Messenger spacecraft will need to do one earth, two Venus, and 3 Mercury flybys over 7 years to "slow down" enough so that it can finally brake into orbit around Mercury with it's insertion motor.
Actually, the atmospheric pressure of ISS is maintained between 14.1 and 14.9 psi or so, for just that reason. Only the airlocks and some storage volumes are taken below that. Critical equipment is certified to go to low pressures (in case a module depress occurs) but a lot of the non-critical and/or commercial equipment isn't held to that standard (since it could be replaced).
Apollo flew with about 5 psi of pressure, and Shuttle would sometimes depress the cabin to 10.2 psi in prep for spacewalks, but ISS maintains an earthlike atmosphere.
The Space Station Freedom network design was token-ring, but that design was scratched when the redesign happened in the '90s. The McDonnell-Douglas/IBM avionics team was also dropped in favor of Boeing/Honeywell. The only IBM equipment that was used on ISS were Thinkpads.
You are absolutely correct, which is why nothing on these networks is something on which life depends.
I'm going to greatly simplify this, but there are basically three networks onboard the space station. One is mostly off the shelf laptops and networking equipment that runs Windows and is used for crew support (email, procedures, timelines, photos, and such). It frequently needs maintenance, but it does the job. It's also (relatively) easy to certify and plug new hardware into it, so it can be updated frequently as commercial technology advances (for example, later this year the Thinkpad A31p laptops will be swapped out for newer models).
The second is a payload ethernet network that is used by the payload system to collect and downlink high volume data through the USOS Ku-band system. Failure of this network only impacts science collection and some support activities. These switches are part of this network. The standards are more stringent, but not to the level of stuff on which safety or mission success depends.
The third network is the core computer system, which is all custom built hardware/software wired up with MIL-STD 1553 data bus. This is the network which runs the core vehicle systems (life support, attitude control, what have you). The hardware and software are developed to a much more rigorous standard than the first two networks (and it obviously costs a lot more and is slower to update because the the long pole of certification and testing). Some of the machines on this network have been chugging along for nearly a decade without failure.
Actually it's the US segment of ISS that uses the 386 based machines (although a couple may go to Pentiums in a few years).
The Orbiter uses the AP-101S, which was also used in military aircraft. NASA has a great deal of published history online regarding Shuttle Avionics here.
Interesting article. It was written just after the Apollo 6 unmanned test of the Saturn V in 1968.
The mission went quite poorly. 2 engines failed on the second stage, and the third stage engine failed to restart in orbit. Parts fell off the shroud, too.
Still, NASA went ahead and launched the next Saturn V with a crew to the moon (Apollo 8). Another unmanned test was not performed to "save about $280 million and avoid further delays in its program to place U.S. astronauts on the moon in 1969". This has often been called the greatest risk ever taken in the space program, and was motivated by reports that the Soviet Union was preparing for a manned moon flyby. It's a totally different risk matrix than what governs NASA today.
Indeed. In fact, the Saturn V itself had problems with pogo oscillation, a condition that affects liquid fueled rockets and caused the center engine shutdown during the first stage of Apollo 13.
it is my experience that Linux is not yet reliable for mission critical stuff
I work for NASA (who coined the term "mission critical") and we think it's ready. The IBM A31p laptops onboard the Space Station were recently switched to Redhat. These are the laptops that command to the core computer system and control the vehicle, not just some random payload.
Mission Control in Houston is in the process of switching to RHEL based systems, and should be complete sometime next year.
If NASA was based in Ron Paul's home district, I'd bet my dollar to your donut he'd be extolling the virtues of pork--errr... I mean--Martian exploration.
Interestingly enough, Ron Paul's 14th congressional district runs right up against NASA/Johnson Space Center, and includes the suburbs of Friendswood and League City. Those communities are the wealthiest in his district, and are totally dependent on JSC (a large chunk, if not the majority, of JSC's employees live in those cities).
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The launch window is small because ISS has to be essentially lined up in orbit in a tight tolerance (called the phase angle) to rendezvous this quickly. Usually the Soyuz plays "catch up" over 2 days by flying lower (and faster) than ISS. You can control the closing rate between the vehicles by altering the altitude difference between them, which allows you to make up differences in the orbits between the vehicles. Those differences are usually just fallouts of other things, like having uncertainty in launch dates, getting the altitude just right for other vehicles (there is about a rendezvous a month at ISS), etc. It's not because Soyuz is slow, it's because spreading the rendezvous over 2 days gives you some targeting flexibility.
You have less margin to work with when you are trying to get there in 4 orbits instead of 34 orbits. Hitting that target with both ISS and Soyuz is hard but it's more about ground targeting than performance of the launch vehicle. The launch vehicle didn't give any extra oomph to get there faster, the ground essentially had the vehicle phasing in a tight tolerance at launch. They also sped up some of the tracking that was being done and turning that around into updated burns for the next orbit instead of coasting to a set of burns the next day, which was a bunch of work for the ground in a short period of time.
The Russians that devised this actually published it - it's an interesting read if you have access to the journal or want to spend $32:
http://www.sciencedirect.com/science/article/pii/S0094576510001633
About 10 years ago I was at the VAB when all 4 orbiters were at KSC. There are only 3 bays in the Orbiter Processing Facility, and at the time the fourth shuttle was usually in Palmdale on a maintenance rotation. On the rare occasion where all four were at KSC, one had to be left in a corner somewhere waiting for it's turn in an OPF bay.
So, as I walked into the VAB (which is essentially a 50 story open bay, with a lot of open space) off on the left is Discovery, engines out, parked in the corner with a huge tarp suspended over it to protect it from stuff falling from above. It looked a little forlorn over there - literally "parked with a sheet over it". It was sort of surreal, because it was like seeing someones old project car in the corner of their garage, except it was an orbiter.
Anyways, even in this sort of storage you wouldn't be able to fly it again. The engineering and manufacturing infrastructure which supports the shuttle has been dissolved or is in the process of being dissolved. The physical orbiter was only a small piece of that infrastructure, which ran the gamut of things from trajectory analysts, simulators, manufacturing facilities for tanks, a control center staffed by trained personnel, etc. etc. It's not like pulling an aircraft out of storage, restoring it, and flying it. The space industry and space systems are still very specialized and rely on significant amounts of engineering, specialized equipment, and specialized knowledge on the part of the engineers and technicians supporting a particular system. Hopefully that will change soon.
I'd take it more as the white room crew making a patriotic statement than a religious reference. In many of the employees, there is a pretty significant sense of national service, both on the part of the government and contractor employees. I would say the majority of employees (at least the ones I worked with, who were mainly engineers) were primarily motivated by things other than a paycheck, which in most cases was smaller than a similar private sector position.
One interesting thing about the "God" reference - I'm not particularly religious, but to some it was not all about the science and engineering when there are people onboard. I've worked manned and unmanned launches. When there are people you actually know and work with daily onboard, it's got a whole different sense about it - and it would cause religious feelings to well up in some people who ordinarily were fairly agnostic.
She didn't make it up, she quoted a senior official - the Boeing payload manager at KSC (Mike Kinslow). This is the first public mention that I've seen, but it is in the planning stages (as a recent addition, which is why this is the first public mention of it).
So what DO you do when the battery charger bursts into flames on orbit?
I'll reinforce your point here. Knowing something about the fire response strategy on ISS you do the following:
1) If you actually are lucky enough to witness the charger burst into flames, remove the power from it, hit the fire alarm, put on a mask, and expend a CO2 based fire extinguisher on it. The mask keeps you from asphyxiating yourself with the extinguisher.
2) If you don't physically see what happens (which is most likely, ISS is big and some modules may go unattended for hours) - the combustion products will trip off a cabin smoke detector in the module. That will stop ventilation inside the module and ring the alarm. In most cases, this will put out a fire in zero g - fires tend to smother themselves without gravity to force convection currents.
Meanwhile, not having any knowledge other than a smoke alarm from a module, the crew will converge in a safe haven in the vehicle away from the fire. Two (of the 6) may go forward to investigate with masks, fire extinguishers, and a hand held device to detect combustion products (mainly so they know if they are entering a lethal pocket of CO or other gases). Hopefully the module isn't a total fog of combustion products - if it is, the crew is likely to isolate it and leave it. If you don't know what the fire source is (because you can't see it), it may well end up that the entire module ends up getting powered down to ensure an electrical fire isn't being fed. This of course has some pretty serious ramifications as well - shutting down power to a module is not a simple event to reverse (since all the computers, cooling, lights, etc. go down with it). It's likely that collateral damage to a module's systems would happen if that were done.
Even if you do understand what happened and know it's out, the harmful gases from burning plastic aren't going to just go away on their own, they have to be scrubbed out with deployed fans and special canisters. It would take weeks to clean up.
Fighting a fire in a closed environment is very different than something you would do in your home. In zero gravity, most of the control is by prevention - don't use flammable materials, stop ventilation on a detected fire so it doesn't spread, don't use things that generate poison air when they burn, etc. Even a minor fire that many of us have encountered at one time or another (smoked electronics, plastic bag on fire, etc.) would be an extremely serious event in space. That's why so much time is spent making sure equipment conforms with fire prevention standards.
Disclaimer - I work for NASA.
I don't think the cost per kg of cargo is a driving factor on this decision. The US government has a vested interest in supporting both SpaceX and Orbital on the COTS contract. If successful the vehicle SpaceX is developing will provide a domestically produced launch vehicle that has shows some promise in having a lot of launch flexibility and much cheaper rides to orbit.
Additionally, if SpaceX is successful it will provide some negotiation power in getting upmass to ISS (the rides get more expensive when Progress is the only game in town) and will also provide some competition on government contracts to the United Launch Alliance consortium of Boeing and Lockheed Martin.
We actually had an interesting situation where I work (spacecraft operations). We had a senior aerospace engineer depart after 15 years to become an airline pilot, of all things (decided to turn a hobby into a job).
About a year later, he came back part time because the routes he flew left him with large blocks of free time at irregular periods during the month, and he was getting bored (because before his "hobby" was flying....and he stopped doing that on his days off!).
It was a win-win situation. He'd give us 40-60 hours a month of hourly work when it was convenient for him. We kept his hopper full of things like documentation, training, and other stuff that most senior guys consider dreg work. Even though he now has enough seniority to avoid pilot furloughs, he'll volunteer to drop his flight hours if the airline needs him to. He just increases his hours with us (and he's so good, we'll take whatever he gives us up to full time).
Since he's not interested in advancing up the ladder, he really does a great job on this low-visibility stuff that really helps an organization run well if it's done right.
I understand your point, however this particular software is basically a system for tracking vehicle "funnies" on the ground, it's not something that is in the loop of the vehicle flight software or something used to make critical decisions. The old system is pretty dated and unwieldy to use (I've used it, I work for NASA). We're obligated to try out cheaper alternatives to custom code to see if it works for us without compromising what we are trying to do.
Sometimes it does work for us - the Mission Control Center workstations and the onboard command and control laptops on the Space Station were all recently converted to Red Hat. It is in many ways better than the old proprietary unix solutions because with the source it's easy to do our own mods to the software. We still test the daylights out of it since that is critical software, but it's a lot easier to support since we have the source code and can do our own bug in-house bug investigations, patch it, or rip out things we don't want/need.
I guess I'll take exception to calling astronauts the "annointed elite". Read through the biographies of the current crop of astronauts, and you'll see a pretty broad demographic of military officers, researchers, doctors, and even a teacher. Almost all came from a middle class background and got where they are through hard work.
The astronaut selection process is completely merit based, albeit extremely selective (since there's way more applicants than openings).
I'd be interested in what your propose NASA do to put "normal citizens" into space. Right now NASA and a couple of other government agencies are SpaceX's main funding source, and SpaceX probably has the best chance of coming up with a private ride to orbit for normal (albeit rather rich) citizens to go to space based on this work.
He did say it might take two trips.
One Soyuz couldn't get there but two, flown serially, certainly could.
I think the extra trips was referring to the number of crew members onboard the orbiter (since Soyuz only has three seats, and really you do need two people to fly it).
I don't understand how flying Soyuz "serially" is going to get it to 28.5, if you could elaborate. The amount of propellant to do that kind of plane change is enormous, even the shuttle (which was designed do a lot of maneuvering) is only capable of doing a couple of degrees.
The cost is actually far less than you believe. The "rescue" shuttle is simply the vehicle for the next flight (minus payload). It's already going through the normal processing flow to ready it for its planned launch in November. The additional cost to protect for a rescue mission is in the low millions.
I was wondering though does the ISS have more than one place to dock a shuttle? Or do they have to somehow undock the damaged craft after the crew disembark and then dock the rescue craft? Or does the whole rescue process happen while both craft are undocked and the crew do a cool space dive between shuttles?
The damaged orbiter is undocked first by remote control from the ground. The crew needs to install a cable to allow the command to open the docking system hooks (which is normally a push button the crew performs on the aft flight deck) to be sent from the ground.
If you really want to see everything in excruciating detail, this NASA pdf has it...
http://www.nasa.gov/pdf/153444main_CSCS_Resource_%20Book.pdf
Pay the Russians to get a Soyuz ready? Although it might take two trips...
The orbital inclination of Hubble is 28.5 degrees (essentially due east from Kennedy Space Center). The Soyuz pad at Baikonur is too far north to reach that inclination without doing a plane change, which takes more propellant than Soyuz carries.
The interesting thing is that in order to get such an orbit, it has to pass over other countries. Will Google take footage of other countries? If so, will it use that footage? That would probably require some intense international negotiations.
Actually, it will not. I'm not sure if it's codified anywhere in international law or just by historical precedent, but a nation's airspace does not extend into space. A satellite can legally take photos of anything it can see, and there's little a country can do about it except hide things under cover or shoot it down (which likely would be considered an act of war).
Some countries (like the US) can exert control in limited ways by restricting operations if the imaging company does business in the country, but that's it.
Google has quite detailed satellite photos of Pyongyang, North Korea - I'm sure they didn't really agree to that.
The calculated miss distance was about a mile, but there was uncertainty in that miss distance such that there was a 1 in 72 chance it wouldn't miss the ISS, but instead hit it directly.
To answer your question (at a high level), the sensors and models that are used to track and predict the debris locations have associated mathematical models that can put a number on the uncertainty of where that debris is. The uncertainty takes into account things like how many radar obs were made, the inherent accuracy of the radar, uncertainties in atmospheric drag, etc. You can never know exactly where an object is, only an approximation of the current and future location and a mathematical confidence in that estimate. In this case that confidence was sufficiently low (and the risk of impact high enough) that a collision avoidance maneuver was executed.
One of the things that makes airline accidents so deadly isn't necessarily the altitude, but the speed and the fact that these things are carrying so much damn fuel. I wonder which has more energy, the envelope of the Hindenburg or your average passenger jet fuel tank...
Interesting question. I did some quick googling and math. I wasn't particularly careful, so corrections are welcome.
The Hindenburg had a gas volume of 200,000 m^3, at 0.089 kg/m^3 standard density of hydrogen gas, that is a total hydrogen load of 17,800 kg. Hydrogen has a high energy density of 143 MJ/kg.
A fairly heavily loaded 747 will be carrying 136,000 kg of Jet-A at 43 MJ/kg.
So, the 747 has more than twice the energy onboard, although smaller jets would be rougly equal, all depending on the fuel load. I also did not include the diesel onboard the Hindenburg (or its rather flammable aluminum paint).
One significant difference between hydrogen and Jet-A burning is that the hydrogen is going to rise once the gas bags rupture and not hang around on the ground like Jet-A.
To change the orbit to intersect the sun, a tremendous amount of velocity would need to be removed from the current orbit. It would take more propellant to get it to the sun than it took to launch it from the earth in the first place.
It's actually quite difficult to "hit the sun", the Messenger spacecraft will need to do one earth, two Venus, and 3 Mercury flybys over 7 years to "slow down" enough so that it can finally brake into orbit around Mercury with it's insertion motor.
Actually, the atmospheric pressure of ISS is maintained between 14.1 and 14.9 psi or so, for just that reason. Only the airlocks and some storage volumes are taken below that. Critical equipment is certified to go to low pressures (in case a module depress occurs) but a lot of the non-critical and/or commercial equipment isn't held to that standard (since it could be replaced).
Apollo flew with about 5 psi of pressure, and Shuttle would sometimes depress the cabin to 10.2 psi in prep for spacewalks, but ISS maintains an earthlike atmosphere.
The Space Station Freedom network design was token-ring, but that design was scratched when the redesign happened in the '90s. The McDonnell-Douglas/IBM avionics team was also dropped in favor of Boeing/Honeywell. The only IBM equipment that was used on ISS were Thinkpads.
You are absolutely correct, which is why nothing on these networks is something on which life depends.
I'm going to greatly simplify this, but there are basically three networks onboard the space station. One is mostly off the shelf laptops and networking equipment that runs Windows and is used for crew support (email, procedures, timelines, photos, and such). It frequently needs maintenance, but it does the job. It's also (relatively) easy to certify and plug new hardware into it, so it can be updated frequently as commercial technology advances (for example, later this year the Thinkpad A31p laptops will be swapped out for newer models).
The second is a payload ethernet network that is used by the payload system to collect and downlink high volume data through the USOS Ku-band system. Failure of this network only impacts science collection and some support activities. These switches are part of this network. The standards are more stringent, but not to the level of stuff on which safety or mission success depends.
The third network is the core computer system, which is all custom built hardware/software wired up with MIL-STD 1553 data bus. This is the network which runs the core vehicle systems (life support, attitude control, what have you). The hardware and software are developed to a much more rigorous standard than the first two networks (and it obviously costs a lot more and is slower to update because the the long pole of certification and testing). Some of the machines on this network have been chugging along for nearly a decade without failure.
Actually it's the US segment of ISS that uses the 386 based machines (although a couple may go to Pentiums in a few years).
The Orbiter uses the AP-101S, which was also used in military aircraft. NASA has a great deal of published history online regarding Shuttle Avionics here.
Interesting article. It was written just after the Apollo 6 unmanned test of the Saturn V in 1968.
The mission went quite poorly. 2 engines failed on the second stage, and the third stage engine failed to restart in orbit. Parts fell off the shroud, too.
Still, NASA went ahead and launched the next Saturn V with a crew to the moon (Apollo 8). Another unmanned test was not performed to "save about $280 million and avoid further delays in its program to place U.S. astronauts on the moon in 1969". This has often been called the greatest risk ever taken in the space program, and was motivated by reports that the Soviet Union was preparing for a manned moon flyby. It's a totally different risk matrix than what governs NASA today.
Indeed. In fact, the Saturn V itself had problems with pogo oscillation, a condition that affects liquid fueled rockets and caused the center engine shutdown during the first stage of Apollo 13.
it is my experience that Linux is not yet reliable for mission critical stuff
I work for NASA (who coined the term "mission critical") and we think it's ready. The IBM A31p laptops onboard the Space Station were recently switched to Redhat. These are the laptops that command to the core computer system and control the vehicle, not just some random payload.
Mission Control in Houston is in the process of switching to RHEL based systems, and should be complete sometime next year.
If NASA was based in Ron Paul's home district, I'd bet my dollar to your donut he'd be extolling the virtues of pork--errr... I mean--Martian exploration.
Interestingly enough, Ron Paul's 14th congressional district runs right up against NASA/Johnson Space Center, and includes the suburbs of Friendswood and League City. Those communities are the wealthiest in his district, and are totally dependent on JSC (a large chunk, if not the majority, of JSC's employees live in those cities).