On 9/06/2019 10:08 am, JF Mezei wrote:
On 2019-06-08 16:18, Fred J. McCall wrote:

Most capsules aren't pure ballistic objects. They can generate lift.

At 340km altitude, do they generate any lift? Aren't they pure ballistoc
at that point?

Near enough, but the deorbit burn can be timed/adjusted to put the
spacecraft into a suitable gap between the satellites, while still
allowing the targeting of a specific landing point.


99.6% clear. The 400 ms at most that you can't fly through aren't
going to appreciably affect anything.

So what you are stating is that NASA is perfectly OK with de-orbiting
any any time because the odds of being at the wrong place and wrong time
during that 400ms are so low as to not even bother?

I don't think that was the point being made. Rather that any orbital
modification required to achieve a 400ms change can be dealt with later
during the non-ballistic phase.



If they do "aim" to take the threat seriously and pass between 2
satellites based on their orbital elements, is there confidence that a
de-orbit burn can not only start right on time (easy) but also
decelerate at the exact rate (consider a capsule's mass may not be fixed
depending on what cargo they are returning) such that they will cross
path with Starlink orbit at just the right time?


The craft can measure its deceleration, so it's not just dead-reckoning.

Sylvia.