In message , Pat Flannery
writes
Our local PBS station ran a special tonight on the MER spacecraft and
their rovers design, testing, and launch (as well as the successful
landing of #1)
The show was chock-full of info on the rovers and what they can
do;Which if they work right is very impressive- but in my opinion
showed a major flaw in the program timeline that led up to their
launch...in the last few months before the launch, the MER team runs
into no less than _5_ unexpected problems, any one of which is a
complete show-stopper if not fixed:
1.) An attempt to use a Pathfinder type parachute for the descent of
the rovers fails after a helicopter drop, as it is not structurally
strong enough to take the extra weight of the MER probes.
2.) A redesigned chute fails to open properly in wind tunnel tests. Its
central hole is too large and this makes it "squid" as it attempts to
open, due to too much airflow out of the top. The test that fixes this
flaw is done by sewing in a constraint around the top hole; and holding
the chute reefed via two guys in the wind tunnel with a cord at the
apex of its shroud lines; as there is neither time nor money to do
another test ejection from its canister. The chute is found to have
been built to the wrong specifications, and a redesigned one has to be
made in short order to correct the flaw.
3.) One of the landing airbags ruptures during a bounce test. Again
unexpected...again fixed with a few months to go.

Beagle 2 had the same set of problems, but sadly it doesn't seem to have
survived them.

I will not even comment on the idea to launch the probes before their
landing software was completed; and then uploading it to them
in-flight-

There's a precedent for that. One of your probes (NEAR ??) was being
tested for millennium compliance in mid-flight.
--
Rabbit arithmetic - 1 plus 1 equals 10
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