[AR] Re: Ionic orientation (was: Falcon 9 flight today)
- From: Ian Garcia <ianmga@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Sun, 6 Oct 2013 22:40:22 -0700
Norman, after reading the mention to Ion Sensors I remembered the
hilarious stories of Ion sensors giving all sorts of trouble and
Chertok's rants against them (hilarious to us reading it many years
later, it wasn't funny at all to them then). I am glad you brought it
up. I highly recommend those books to anybody building rockets
ian
On Sun, Oct 6, 2013 at 4:02 PM, Norman Yarvin <yarvin@xxxxxxxxxxxx> wrote:
> On Sun, Oct 06, 2013 at 03:43:42PM -0600, Ben Brockert wrote:
>>For anybody else who hadn't heard of this system: it turns out that
>>from 60 to 40,000+ miles there are a useful number of thermal ions,
>>and the positive ions are basically stationary from the perspective of
>>an orbiting craft. Counting those ions with negatively charged sensor
>>grid/plate setups you can get pitch and yaw values relative to
>>direction of motion.
>
> Oh, so that's how the system Chertok writes about in "Rockets and
> People" works.
>
> It didn't always work correctly, though; they ran into nonuniformities
> in the ion cloud or something. On their first orbital rendezvous
> success:
>
> "On day two, the ionic orientation failed, falling into “ion
> pockets.”"
>
> ...
>
> "...after somehow setting up the spacecraft using the ionic
> system, the commands were issued to start up the descent cycle
> programs. The ionic system slipped up somewhere in the
> Brazilian Magnetic Anomaly, and the braking burn sent the
> spacecraft toward Earth on a long, flat trajectory that
> emerged beyond the limits of the authorized corridor."
>
> (whereupon it was destroyed by the self-destruct system)
>
> That led them to decide that:
>
> "Ionic orientation was unreliable. The system needed to be
> supplemented with an infrared sensor. This would provide
> reliable pitch and roll orientation."
>
> Of course, today we could do a lot more to detect and properly handle
> such "ion pockets" than they could with 1960s Soviet electronics.
> (Hmm, would their problem have been running into the Van Allen belts?)
>
>
> --
> Norman Yarvin http://yarchive.net/blog
>
--
Ian M Garcia
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