Quote from: Robotbeat on 08/08/2012 07:44 pmWhat's the angular distribution of MMOD?Predominantly from behind and the sides. Stuff coming in from the front is going slower, so has a lower perigee, so has experienced more atmospheric drag and is likely to be scrubbed out of orbit relatively quickly. That's one reason the ISS orbit is not higher, I believe.Ditto on things coming in from below. They have seen more drag. (However, there was a strike on the Cupola.)Same altitude orbits in different inclinations approach from the sides.Stuff in elliptical orbits with higher apogees comes in from behind.The front of the ISS is probably a relatively safe place, particularly if the VV doesn't stick out like the Shuttle did.Someone must have quantitative data. Look online for orbital debris quarterly reports from NASA.
What's the angular distribution of MMOD?
Runway length is only a small element in this. You can have a 15k Ft. runway waiting for you but if you do not have exact onboard, ground, and visual guidence to take you to the approach end of that runway- in the proper attitude and at the proper airspeed, the length does not mean squat. Thus, there may not be "plenty of choices."
Runways of 3km or more are not common and busy commercial airports are loath to consent to be used for emergency landings of spacecraft. The entire world was surveyed repeatedly for runways for both Shuttle and CERV. The short answer is that they exist, but not in profusion. The Shuttle emergency landing sites around the world are well known; the majority are military fields that could be cleared quickly for an emergency landing. The approach cannot possibly be hand-flown, particularly with something like the DC which has very little aerodynamic reserve; everything from TIG to wheel stop must be autonomous. This was never possible with Shuttle, which predated even GPS. It had an autoland system but it was organizationally infeasible to even test it. In contrast the X-37 has so far made two completely autonomous landings with no significant problems.
Quote from: vulture4 on 09/02/2012 05:54 amRunways of 3km or more are not common and busy commercial airports are loath to consent to be used for emergency landings of spacecraft. The entire world was surveyed repeatedly for runways for both Shuttle and CERV. The short answer is that they exist, but not in profusion. The Shuttle emergency landing sites around the world are well known; the majority are military fields that could be cleared quickly for an emergency landing. The approach cannot possibly be hand-flown, particularly with something like the DC which has very little aerodynamic reserve; everything from TIG to wheel stop must be autonomous. This was never possible with Shuttle, which predated even GPS. It had an autoland system but it was organizationally infeasible to even test it. In contrast the X-37 has so far made two completely autonomous landings with no significant problems.I assume the problem is that any airport with a suitable runway, is that the airport likes to use them for landing airplanes. For instance, I assume you technically could land the DC at OHare, DFW, Atlanta, LAX, Denver, etc. But that would probably mean shutting down all aircraft operations for hours. And then, losing a major airport for hours means major air traffic delays that ripple across the entire system.
Quote from: Lurker Steve on 09/02/2012 02:06 pmQuote from: vulture4 on 09/02/2012 05:54 amRunways of 3km or more are not common and busy commercial airports are loath to consent to be used for emergency landings of spacecraft. The entire world was surveyed repeatedly for runways for both Shuttle and CERV. The short answer is that they exist, but not in profusion. The Shuttle emergency landing sites around the world are well known; the majority are military fields that could be cleared quickly for an emergency landing. The approach cannot possibly be hand-flown, particularly with something like the DC which has very little aerodynamic reserve; everything from TIG to wheel stop must be autonomous. This was never possible with Shuttle, which predated even GPS. It had an autoland system but it was organizationally infeasible to even test it. In contrast the X-37 has so far made two completely autonomous landings with no significant problems.I assume the problem is that any airport with a suitable runway, is that the airport likes to use them for landing airplanes. For instance, I assume you technically could land the DC at OHare, DFW, Atlanta, LAX, Denver, etc. But that would probably mean shutting down all aircraft operations for hours. And then, losing a major airport for hours means major air traffic delays that ripple across the entire system. That's just entirely inaccurate. Any time any aircraft declares an in-flight emergency, the airport in question can get clear and ready for them in seconds or tens of seconds. This happens all the time right now without causing major ripples throughout the system. Weather events cause a lot more havoc. Second, even if DC did have to land quickly at some random airport, that would only close one runway for a short time, not the whole airport for a long time. It's not a big craft, and it's non-toxic.
Quote from: Lee Jay on 09/02/2012 02:57 pmQuote from: Lurker Steve on 09/02/2012 02:06 pmQuote from: vulture4 on 09/02/2012 05:54 amRunways of 3km or more are not common and busy commercial airports are loath to consent to be used for emergency landings of spacecraft. The entire world was surveyed repeatedly for runways for both Shuttle and CERV. The short answer is that they exist, but not in profusion. The Shuttle emergency landing sites around the world are well known; the majority are military fields that could be cleared quickly for an emergency landing. The approach cannot possibly be hand-flown, particularly with something like the DC which has very little aerodynamic reserve; everything from TIG to wheel stop must be autonomous. This was never possible with Shuttle, which predated even GPS. It had an autoland system but it was organizationally infeasible to even test it. In contrast the X-37 has so far made two completely autonomous landings with no significant problems.I assume the problem is that any airport with a suitable runway, is that the airport likes to use them for landing airplanes. For instance, I assume you technically could land the DC at OHare, DFW, Atlanta, LAX, Denver, etc. But that would probably mean shutting down all aircraft operations for hours. And then, losing a major airport for hours means major air traffic delays that ripple across the entire system. That's just entirely inaccurate. Any time any aircraft declares an in-flight emergency, the airport in question can get clear and ready for them in seconds or tens of seconds. This happens all the time right now without causing major ripples throughout the system. Weather events cause a lot more havoc. Second, even if DC did have to land quickly at some random airport, that would only close one runway for a short time, not the whole airport for a long time. It's not a big craft, and it's non-toxic.Thank you. I was about to post nearly exactly the same thing. All DC needs to know is where they are and where the runway is and their flight avionics will take it from there. Once notifying the tower that they are making an emergency landing the runway will be clear and ready for them when they get there. No airport will ever refuse an emergency landing to anybody, aircraft or spacecraft, once an emergency is declared.
That's just entirely inaccurate. Any time any aircraft declares an in-flight emergency, the airport in question can get clear and ready for them in seconds or tens of seconds. This happens all the time right now without causing major ripples throughout the system. Weather events cause a lot more havoc. Second, even if DC did have to land quickly at some random airport, that would only close one runway for a short time, not the whole airport for a long time. It's not a big craft, and it's non-toxic.
Not that it really matters: I don't think airports really care whether it is a normal aircraft or a spacecraft making an emergency landing.. an emergency is an emergency...
Quote from: belegor on 09/02/2012 06:22 pmNot that it really matters: I don't think airports really care whether it is a normal aircraft or a spacecraft making an emergency landing.. an emergency is an emergency...And there are tons of emergencies declared each year. DC isn't likely to add to that by any significant amount compared to, say, bird strikes causing engine damage.
Except DreamChaser (or any orbital vehicle) is more likely to abort than an airliner is (proportional to number of flights per year per vehicle). This extra burden (more than usual) is borne by the airports. This is called an externality in economics.
...I've always wondered what happens if (billion billion to one chance I hope) the proverbial lost bolt hits the wind shield and goes through *all* the layers. ...
Quote from: Lee Jay on 09/02/2012 06:51 pmQuote from: belegor on 09/02/2012 06:22 pmNot that it really matters: I don't think airports really care whether it is a normal aircraft or a spacecraft making an emergency landing.. an emergency is an emergency...And there are tons of emergencies declared each year. DC isn't likely to add to that by any significant amount compared to, say, bird strikes causing engine damage.Except DreamChaser (or any orbital vehicle) is more likely to abort than an airliner is (proportional to number of flights per year per vehicle). This extra burden (more than usual) is borne by the airports. This is called an externality in economics.
Shuttle did aborted.. to orbit. But still an abort. The big question would be about a pad abort, for example. Or an abort and ditch.
I'm not sure it's even *legal* to land at a commercial airport in the US without one and it's definitely the "neighborly" thing to do
(If DC did carry a transponder, would they squawk 1701?)