From: sylvia@email.invalid   
      
   On 14-Feb-21 9:15 am, Alain Fournier wrote:   
   > On Feb/13/2021 at 16:02, Jeff Findley wrote :   
   >> In article , jfmezei.spamnot@vaxination.ca   
   >> says...   
   >>>   
   >>> On 2021-02-12 18:34, Sylvia Else wrote:   
   >>>   
   >>>>> I know Columbia had not even close to enough fuel to change its orbit   
   >>>>> and gently dock to ISS.  So not debating this at all.   
   >>>>   
   >>>> It would have to fire its engines near apogee to circularise its orbit.   
   >>>   
   >>> Columbia would not only have had to raise its orbit but also change   
   >>> inclination in order to dock to ISS.  My question pertains to what it   
   >>> would need to just "pass by" the ISS once without docking, and wheher   
   >>> the speed differences might be low enough to allow untethered transfere   
   >>> from one to the other.   
   >>   
   >> No.   
   >>   
   >> Jeff   
   >   
   > Jeff's answer is correct. But to give a little more details, without   
   > having checked what were the orbital parameters, the speed differences   
   > would most likely have been several km/s.   
   >   
   >   
   > Alain Fournier   
      
   I was looking at   
      
   https://en.wikipedia.org/wiki/Orbital_speed#Instantaneous_orbital_speed   
      
   This seems consistent across various pages, and I rather suspect my   
   ageing brain is misconstruing it somehow. It seems to imply that the   
   instantaneous orbital speed at a given distance from the centre is only   
   a function of the semi major axis. This in turn would imply that if two   
   orbits coincide at apogee, they'd have the same length of semi major   
   axis, and the same distance from the centre, and therefore the same   
   orbital speed.   
      
   Which is clearly nonsensical. So where am I going wrong?   
      
   Sylvia.   
      
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