JF Mezei wrote on Sun, 9 Jun 2019
12:54:15 -0400:

On 2019-06-09 09:44, Jeff Findley wrote:

Capsules have an offset CG and that combined with their conical (or
biconic) shape produces lift as they pass through the atmosphere.

How much control do they have during that phase? And if they can control
it, how is that accomplished? would thrusters still be effective in
rotating the capsule to change its centre of gravity?


Scads and oodles. It's sort of the point of building them that way.

That's not what he said. The 400ms in time difference would be between
the "ideal" reentry burn time and one which had to be chosen to "miss" a
Starlink.

Thanks you you and Sylvia Else for explaining that part. But I am still
curious on what sort of safety standards will be set. If you have a
satellite passing every 2 minutes, how many seconds AFTER a satellite
has passed will be be safe to descend through that altitude, and what
will be the minimum of seconds BEFORE a satellite arrives that it will
be considered safe to pass through ?


Much less than a second. This has been answered multiple times. Write
it on your ****ing hand so that you'll remember it. You want to play
it both ways: the satellites are fast so there's only a couple of
minutes in between them but you then want to act like they linger in
the area when instead they are cooking along at 7.5 km/sec.

You're one of those people who drives onto the on ramp to a highway
and stops, waiting for there to be no oncoming cars in sight, aren't
you?


And will there need to be new policies in place to freeze
Starlink/Oneweb"whatever orbits X amount of time before a re-entry
(aka: no adjusting of orbits with their engines) to ensure the
re-entering ship is using accurate orbital data of those satellites when
calculating the precise re-entry time?


Bull****. In fact, you could work it just the reverse and require the
satellite to 'dodge'. They'll already be carrying a debris database
so they can alter orbits to avoid all those things. Adding one more
contraint would be trivial.

Again, look at the landing accuracy of Apollo capsules. This was
achieved partly due to their ability to generate a significant amount of
hypersonic lift.

How much was done with parachutes?


None. Have you never seen a spacecraft come down by parachute? They
use big round non-steerable chutes. In fact, one of the sources of
inaccuracies back in those days was wind drift due to insufficient
knowledge about winds aloft.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn