Former astronaut, senator Glenn hurt in car crash

Jeff Findley wrote:

From a historical spaceflight perspective, it's the first few hundred miles
and the last few hundred (or thousand) miles that are the most risky. LEO
is such a benign environment that all those miles after orbit insertion and
before the deorbit burn aren't nearly as risky.


There've been some close calls in LEO, including the Mir fire and
Progress collision, and the Gemini 8 acrobatics with the Agena.
As far as getting beyond LEO, we have Apollo 13 to contend with.
In the case of airliners most of the actual fatalities are caused by the
aircraft interacting badly with the ground or other objects during the
takeoff or descent phase of the flight... particularly if the descent
phase happens to be nose-first in a unintended area at around 500 mph. ;-)

Pat

Pat

Andre Lieven wrote:

How is it in a per hour flown basis ? Its mildly disingenuous to use
distance travelled, especially in LEO flight, as no other mode of human
travel to date comes within even an order of magnitude of LEO velocities.



In that case one can go back to the hours per country figures:
http://www.hoerstemeier.com/nation.htm
As of January 1st, 2001 Russia had one fatality around every 4,047
days of flight or 97,128 flight hours, the U.S. one fatality around
every 651 days of flight, or 15,624 flight hours (leaving out Mike
Adams' fatal X-15 flight, and including Komarov's fatal landing).
Other that that, the only other nation to lose a astronaut was
Israel...or did Kalpana Chawla still hold duel American/Indian
citizenship when she was lost on Columbia?
Averaged out by all nations on that list it looks like around one
fatality per 1,415 flight days or 33,954 flight hours.

Pat

Derek Lyons wrote:

I wasn't trying to determine some deep insight from it, just get the
figure out of curiosity.



Such a claim is rendered into actual form - utter bull**** by your
very next paragraph.


Hell, I want to know why toxic blowfish aren't as brightly colored as
other toxic or venomous animals, but rather inflate and use their spines
for defense while remaining pretty drab in color, even though they are
highly toxic to consume.
That doesn't mean I'm trying to figure out any great law of ichthyoid
evolution from finding out why. I just find it odd and would like to
know more. :-)
Remember this from back on the 5th?



wrote:

One wonders if it is indeed more safer to travel in space than to drive
on earth.


According to those figures David Palmer found, it appears that
spaceflight is safer than driving your car, but not as safe as flying on
a commercial airliner as a means of transportation goes, on a per-mile
basis.



That's nice. But irrelevant.


No... it's not a figure of any great import, but on a per mile basis it
does appear to be safer to fly in space than drive in a car.
Just a odd little statistic, that's all.

Pat

Derek Lyons wrote:

That's precisely Jeff's point - usually miles traveled is a factor of
merit, but the LEO ops isn't one of those cases. The devil is in the
details.


What about space debris? The more orbits you make the more likely you
are to encounter a piece of it, and the faster you are going the more
likely that impact will have severe consequences.
When you think about it, in LEO mileage and flight hours are pretty much
interchangeable due to being in freefall.

Pat

Neil Gerace wrote:

I wonder how safe (Mean time between deaths) a car would be with the engine
absent, like a spacecraft in LEO.



I would imagine it would be something like coasting downhill with the
motor shut off- engine problems can be pretty much eliminated, but you
had better hope the steering and brakes still work when the bull wanders
out on the road a few hundred feet ahead.
In this case the bull could be the size of a spent upper rocket stage
going at 18,000 mph, or something as small as a pea heading Earthwards
at around 175,000 mph.
(as the crowd cheers, the daring Mir Matadors turn their backs on the
approaching Progress, and show contempt for its speedy advance on their
red rears.) :-)

Pat

Pat Flannery ) writes:
Derek Lyons wrote:

That's precisely Jeff's point - usually miles traveled is a factor of
merit, but the LEO ops isn't one of those cases. The devil is in the
details.

What about space debris? The more orbits you make the more likely you
are to encounter a piece of it, and the faster you are going the more
likely that impact will have severe consequences.

Yet, that hasn't happened, and given that at the most frequently manned
orbits, pretty much all the parts are going the same way, the velocity
difference isn't that great.

Now, when two planes hit each other, because they are both in regimes where
course control is a constant requirement ( No ability to turn everything
off and let Newton do the piloting ), that is a far more significant risk,
particularly so as not only is space big, and athmospheres not so much,
but in this case, the not big environment is the one with the loads of
traffic.

Ditto for cars on roads.

When you think about it, in LEO mileage and flight hours are pretty much
interchangeable due to being in freefall.

Thus making a crash unlikely. Unlike in air/ground/ship travel.

Andre

Pat Flannery ) writes:
Neil Gerace wrote:

I wonder how safe (Mean time between deaths) a car would be with the engine
absent, like a spacecraft in LEO.

I would imagine it would be something like coasting downhill with the
motor shut off- engine problems can be pretty much eliminated, but you
had better hope the steering and brakes still work when the bull wanders
out on the road a few hundred feet ahead.

Yet, on LEO, you don't need steering or brakes, in the sense of
don't-fail-to-use-either-correctly-for-more-than-5-seconds-and-you-
will-crash sense.

So, this comparison is also apples and Buicks.

In this case the bull could be the size of a spent upper rocket stage
going at 18,000 mph, or something as small as a pea heading Earthwards
at around 175,000 mph.
(as the crowd cheers, the daring Mir Matadors turn their backs on the
approaching Progress, and show contempt for its speedy advance on their
red rears.) :-)

Andre

Andre Lieven wrote:

What about space debris? The more orbits you make the more likely you
are to encounter a piece of it, and the faster you are going the more
likely that impact will have severe consequences.



Yet, that hasn't happened, and given that at the most frequently manned
orbits, pretty much all the parts are going the same way, the velocity
difference isn't that great.


Shuttle and Hubble have gotten nicked a few times by space debris over
the years. According to this:
http://www.orbitaldebris.jsc.nasa.gov/faqs.html average impact speed
between a spacecraft and orbiting debris will be around 10 km per
second. (see #7) I imagine the problem stems from different orbital
inclinations from polar to equatorial and the fact that such things as
chipped paint will spiral in toward reentry fairly fast due to their
high drag in relation to their mass, and so may be encountered at any
given orbital altitude under their initial one.
Check out #9, BTW:

"How did the Mir space station fare during its 15-year stay in Earth orbit?
Photographs of Mir's exterior show large numbers of impacts from small
orbital debris and meteoroids. The most significant damage was to the
large, fragile solar arrays which cannot be protected from small
particles. Orbital debris caused no loss of mission or capability on Mir."

Probably the most famous incident of this sort was the "what's it" that
hit Mir's (or was it a Salyut?) window violently enough to make a noise
and visible flash and caused the crew to retreat to the Soyuz until they
were sure that the station still had pressure integrity.

Now, when two planes hit each other, because they are both in regimes where
course control is a constant requirement ( No ability to turn everything
off and let Newton do the piloting ), that is a far more significant risk,
particularly so as not only is space big, and athmospheres not so much,
but in this case, the not big environment is the one with the loads of
traffic.

Ditto for cars on roads.



When you think about it, in LEO mileage and flight hours are pretty much
interchangeable due to being in freefall.



Thus making a crash unlikely. Unlike in air/ground/ship travel.



How often do you think a ship hits a fish? Of course they don't notice
it, since the fish isn't moving at 10 km/s.
On the other hand, planes do notice when they hit birds, but probably
not when they hit bees. Now imagine hitting a bee going 10 km/s. Light
as it is, it's going to be like getting hit with a rifle bullet.
To give some idea of how common impacts with very small pieces of space
debris are, note that even given the small potential impact area of the
Shuttle's windows in comparison to the overall size of the orbiter, that
when this article was written a total of eight external window panes
from shuttles had been replaced due to impact damage:
http://www.satobs.org/satclose.html
Here's a nice shot of the window impact ding that occurred on the STS-70
mission: http://www.satobs.org/image/sts-70_win.gif
As can be seen whatever hit the window was going fast enough to vaporize
on impact, as the "crater rays" show.
Sooner or later, something will hit a manned spacecraft with enough
energy to pierce its hull. It's just a matter of enough flight hours.

Pat

Andre Lieven wrote:

Yet, on LEO, you don't need steering or brakes, in the sense of
don't-fail-to-use-either-correctly-for-more-than-5-seconds-and-you-
will-crash sense.

So, this comparison is also apples and Buicks.


Mission control tells you that there's a potential impact danger coming
up tomorrow around noon, and you should now change your orbit by around
ten km to make sure you're out of the danger area.
So you fire up the RCS system and...something goes wrong...and one of
the nose RCS thrusters explodes, tearing a hole in the front end of the
orbiter.
Now you've got a major problem regarding doing a reentry in a
aerodynamically compromised vehicle, so it's time to launch the rescue
shuttle.
This hasn't happened yet, and it's a pretty unlikely scenario- but
there's a good chance you could lose a orbiter, if not its crew, if
something like this were to occur. Being on-orbit is a lot safer than
launch or reentry, but it's not perfectly safe by any means.
The thing I'd be concerned about isn't the orbital debris they're
tracking, it's that pebble sized meteor heading earthwards that you are
going to get no clue of the arrival of prior to a hell of a loud bang.

Pat

"David M. Palmer" wrote in
:

In article , Pat Flannery
wrote:

Jeff Findley wrote:


Total number of miles traveled in space is almost always a bogus
figure. You can rack up a lot of "miles" zipping around the earth in
LEO, but never truly go more than a few hundred miles (up and down),
especially if you're taking off and landing at KSC.



I wasn't trying to determine some deep insight from it, just get the
figure out of curiosity.
According to those figures David Palmer found, it appears that
spaceflight is safer than driving your car, but not as safe as flying
on a commercial airliner as a means of transportation goes, on a
per-mile basis.

And airliner deaths per passenger mile are likewise somewhat bogus
since they mostly occur on takeoff or landing so a 5000 mile flight is
not much more dangerous than a 50 mile flight from Dulles to BWI.

I agree, fatalities per passenger-takeoff/landing would be a better metric.
It seems to me that this statistic started out because flights were shorter
early in the aviation age, survived due to bureaucratic inertia, and is
perpetuated because it is biased in favor of long-haul airlines, which tend
to be politically better-connected than their short-haul counterparts.

--
JRF

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