Yup. John is quite right, too, but it's clear that the Mars Lander
project evolved the way it did because funding was not available
for the usual approach - One-off everything, and so on...
There was no prospect of a second effort. No money.

Jack

Russell McMahon wrote:

> But, unfortunately, Mars only allows minimum energy transfer orbits
> only every so not too often so a blown landing opportunity also costs
> you some years wait ...

> > If one builds two of the #1 units, the total cost is $2X (well under
> > that of one design #2 unit) and one has the same probability of
> > success as with the #2 design (there's a 1% chance both will fail).
> > One also has the advantage, however, that if the first one happens
> > to work one has a second one which can be used for further research.

> > > Seems the last Mars lander project did just that.