It is said in Wikipedia, that

On the first orbit, McDivitt attempted to rendezvous with the spent Titan second stage. This was unsuccessful for a number of reasons:

NASA engineers had not yet worked out the idiosyncrasies of orbital mechanics involved in rendezvous,[citation needed] which are counter-intuitive. Simply thrusting the spacecraft toward the target changed its orbital altitude and velocity relative to the target. When McDivitt tried this, he found himself moving away and downward, as the retrograde thrust lowered his orbit, increasing his speed.

I don't understand this.

Is there any explanation, given in local reference frame? Referring "orbital altitude" referrers global reference frame and is OK. But any set can be possibly regarded in any reference frame. Local reference frame should be inertial with tidal, Coriolis and other forces.

How to describe the situation with this?


Suppose we are inside giant closed spacecraft like Rama or O'Neill cylinder. This spacecraft is on Earth orbit, but we are inside and don't know this. We feel weightlessness. Now, If Rama is rotating, we can feel some non-inertial effects like centrifugal or Coriolis forces.

But suppose Rama is not rotating.

Then, the only strange thing we will feel is Earth tidal force. The tidal force mean that all objects will periodically distracted along axis, directed to (invisible) Earth.

So, you want to say, that McDivitt failed due to tidal forces?

Hard to believe.

  • $\begingroup$ Would space.stackexchange.com be a better home for this question? $\endgroup$
    – Qmechanic
    Oct 17, 2013 at 11:51
  • $\begingroup$ One way to check the validity of the tidal explanation would be to verify that the effect of the forces being discussed on a cloud of test particles is to distort the cloud without changing its volume. Another way might be to see if the effect scales like $r^{-3}$. $\endgroup$
    – user4552
    Oct 20, 2013 at 22:24
  • $\begingroup$ Note that in addition to tensile forces radially, tides impose constricting forces in the plane normal to the radius. $\endgroup$ Nov 19, 2013 at 7:44
  • 2
    $\begingroup$ already answered on space exploration stack exchange: space.stackexchange.com/q/2476 $\endgroup$
    – DavePhD
    Apr 30, 2014 at 22:46