re: OSCAR-13 re-entry

Walter Nissen (dk058@cleveland.Freenet.Edu)
Thu, 7 Dec 1995 12:05:58 -0500

> Subject: OSCAR-13 re-entry 
Dave Mullenix writes: 
> >>James says it will re-enter at night, so perhaps somebody will get to 
> >>see the fireball. 
> >Since the earth is 60% sunlight and twilight, I would like to wager 
> >that it won't reenter "at night".  :-)? 
> I'll be happy to cover that bit, but only up to the amount you can afford to 
> lose.  I think G3RUH says it will re-enter on the night side because the 
> orbit will still be quite elliptical when it finally re-enters.  Since the 
> apogee side of the ellipse will be pointed at the sun next December, 
> the perigee side will be on the night side of the planet. 
and continues: 
> I think it's safe to assume that the last orbit will finish with a 
> perigee that turns into a fireball. 
> the near guaranteed night time reentry 
How do you jump from the first statement, which seems quite logical, to 
the second, which seems implausible?  (I should mention that I'm no 
physicist and that I see this in terms of a mathematical model, 
randomization by taking a real value mod 1, such as is used in 
encryption).  Why wouldn't you imagine that the final energy delta will 
result in a residual which is a random fraction of an orbit, originally 
eccentric or not?  If there is empirical evidence for what James says, I 
would readily believe it and chalk it up as a lesson learned, but it makes 
no sense to me. 
Which can never amount to any excuse for not looking. 
Walter Nissen          
Science is the most powerful method ever devised to protect us from
deceiving ourselves.