Your 'spitball' landed pretty close to my 'back of the envelope' calculation that I posted just before I saw your message. I used the numbers from the same graph but with 1,500 MT and a little algebra to come up with 16% (rounded off from 16.4%)
If the impact energy were exactly 1,500 MT it works out to a Torino number of:
9 at 99%
5 at ~16.4%
4 at 1%
2 at ~0.164%
1 at ~0.00164%
Currently the energy is estimated at 1,480. But it has moved a bit in the range of 1,400 - 1,600 which would shift some of the percentages above slightly. It would take a very large shift in enenergy to get other Torino numbers.
Talking of the Torino scale, does anyone have any idea at what percentage probablility of impact it would move up to the orange (threatening) section of the scale? As far as I can tell, both the orange and red (impact!) sections are based more on the predicted amount of damage rather than likelihood of a collision, so I'm guessing it's pretty high. Also, assuming that the estimated size and consistency of the object don't change, it looks like an object would not be given two separate orange or red scores. If that's the case then I'm guessing that if MN4 is going to hit us it'll go to five, then eight based on a play with the damage predictor.
The Torino scale [ref1] is based on kinetic energy in megatons vs. probability of impact. A 4 or 5 is only for objects with energy in the 100 MT to 100,000 MT class and a probability in the 1% to ~99% range. Currently, 2004 MN4 is estimated [ref2] to have an impact energy of about 1,500 MT with a probability of 2.7% To rank a 5 (at the same energy) I calculate that the asteroid would need about a 16% impact probability. It would then stay at 5 for up to 99%
There can only be one Torino integer/color per close earth approach. It could only jump from a 5 to a 9 if the probability exceeds 99% But an 8 (or a 3) are unlikely unless the size estimate is way too high. This asteroid will most likely hover at 4 for some time while new observations are collected. Later, it could drop from 4 to 2 or (less likely) jump from 4 to 9.
[1]Torino Scale from Asteroid and Comet Impact Hazards [2]2004 MN4 Impact Risk (based on 176 observations collected through Dec. 27.084)
plus astronauts would have one sucky time flying the craft by hand to the moon.
For the most part, what the astronauts did was closer to "flying the craft by hand" then the kind of auto-pilot we think of today.
The computers for apollo did pretty straightforward stuff, and were mainly there so the astronauts didn't have to keep doing stuff non-stop. They could still sight stars and calculate there path and manual fire rockets to adjust (like they did in Apollo 13),
The computer did relieve the crew of having to do lots of calculations which allowed them to focus on control of the craft, but some things were done manually - despite the fact that the computer could have done it automatically.
In a transcript (typos in original) of David Scott's remarks, from The Apollo Guidance Computer: A User's View there is an interesting discussion of the auto-pilot capability of the AGC, and then he goes on to say:
"The lunar landing itself could have been done automatically and many times people ask me about that. Could it have been accomplished automatically through the LEM guidance computer? Nobody ever did it. We all felt that when you get that point and you are ging to land on the moon, you have to have your hands on the stick. I like computers and I believe in computers, but it aint going to land me on the moon. I'm going to do that. If something gets screwed up then it is going to me, it isn't going to be the computer. Actually, my thinking at the time was that if a problem did occur it was so time critical that you wouldn't have time take corrective action, so you stay ahead of that problem by flying it manually."
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Your 'spitball' landed pretty close to my 'back of the envelope' calculation that I posted just before I saw your message. I used the numbers from the same graph but with 1,500 MT and a little algebra to come up with 16% (rounded off from 16.4%)
If the impact energy were exactly 1,500 MT it works out to a Torino number of:
9 at 99%
5 at ~16.4%
4 at 1%
2 at ~0.164%
1 at ~0.00164%
Currently the energy is estimated at 1,480. But it has moved a bit in the range of 1,400 - 1,600 which would shift some of the percentages above slightly. It would take a very large shift in enenergy to get other Torino numbers.
The Torino scale [ref1] is based on kinetic energy in megatons vs. probability of impact. A 4 or 5 is only for objects with energy in the 100 MT to 100,000 MT class and a probability in the 1% to ~99% range. Currently, 2004 MN4 is estimated [ref2] to have an impact energy of about 1,500 MT with a probability of 2.7% To rank a 5 (at the same energy) I calculate that the asteroid would need about a 16% impact probability. It would then stay at 5 for up to 99%
There can only be one Torino integer/color per close earth approach. It could only jump from a 5 to a 9 if the probability exceeds 99% But an 8 (or a 3) are unlikely unless the size estimate is way too high. This asteroid will most likely hover at 4 for some time while new observations are collected. Later, it could drop from 4 to 2 or (less likely) jump from 4 to 9.
[1]Torino Scale from Asteroid and Comet Impact Hazards
[2]2004 MN4 Impact Risk (based on 176 observations collected through Dec. 27.084)
plus astronauts would have one sucky time flying the craft by hand to the moon.
For the most part, what the astronauts did was closer to "flying the craft by hand" then the kind of auto-pilot we think of today.
The computers for apollo did pretty straightforward stuff, and were mainly there so the astronauts didn't have to keep doing stuff non-stop. They could still sight stars and calculate there path and manual fire rockets to adjust (like they did in Apollo 13),
The computer did relieve the crew of having to do lots of calculations which allowed them to focus on control of the craft, but some things were done manually - despite the fact that the computer could have done it automatically.
In a transcript (typos in original) of David Scott's remarks, from The Apollo Guidance Computer: A User's View there is an interesting discussion of the auto-pilot capability of the AGC, and then he goes on to say:
"The lunar landing itself could have been done automatically and many times people ask me about that. Could it have been accomplished automatically through the LEM guidance computer? Nobody ever did it. We all felt that when you get that point and you are ging to land on the moon, you have to have your hands on the stick. I like computers and I believe in computers, but it aint going to land me on the moon. I'm going to do that. If something gets screwed up then it is going to me, it isn't going to be the computer. Actually, my thinking at the time was that if a problem did occur it was so time critical that you wouldn't have time take corrective action, so you stay ahead of that problem by flying it manually."
Due to popular demand there are now two mirror sites for the AGC Replica project files:
NASA Office of Logic Design
SpaceRef.com