experience kit. What helped me the most was that I had
the ability to simplify almost anything. No matter how
complicated a problem was, I could simplify it to two or
three essential parameters. Then I could use those “rules
of thumb” to bootstrap myself into each new challenge.
“It’s basically about developing what we call
an ‘expert system’, like the ‘Prospector’ computer
programme developed at the time in the oil industry
to deal with drilling problems, based on expert
consultants’ solutions for different situations. It consisted
of statements such as ‘If such and such happens,
then do this’. They discovered that the consultants
operated on no more than about 200 to 300 rules
of thumb. It was found that the same was true for
surgeons or rocket scientists. I knew what those principles
were for rocket science and space mission design.
With the ability to simplify, I was like an ‘if … then …
else’ computer programme, which helped a lot.”
RS: It must have been more difficult when you moved
from Ranger onto the Mariner Venus programme in
1962, aiming for another planet, rather than the Moon?
KOHLHASE: “Not really, because the principles carry
across, whatever the target. Venus had a different
mass and the approach speeds were different, but
it was easy to translate the targeting concept from
the Moon to a planet, taking into account gravity,
celestial mechanics, Kepler’s laws and so forth. Also,
as the technology improved and we gained more
experience, we felt more comfortable taking on more
complex missions. Although we had fewer people
to do the testing back then, it has always been my
nature and that of most of my colleagues to check
everything so carefully that nothing could possibly be
overlooked, so most of the missions thereafter were
successful, from the mid-1960s, when my own role
carried more responsibility, through to the successful
Cassini launch and Mars Pathfinder missions in 1997.
“However, we really wanted the Mariner-Venus mission
to succeed at JPL, after the Ranger failures. Mariner 2
Mariner 7, following Mariner 6’s flyby on July 31, had its closest approach at a
distance of 3,524 kilometers, in what was the first dual mission to a planet.
By chance, both craft flew over cratered regions and missed both the giant
northern volcanoes and the equatorial grand canyon that were discovered by
Mariner 9. Their approach pictures did, however, show that the dark surface
features long seen from Earth were not canals, as once thought in the 1800s.
was the first successful planetary mission and it passed
Venus more or less where we intended it to (within 22,000
miles of the planet). That was my first planetary mission,
although I did yet not have a management role on it.”
RS: Was the mood of excitement comparable with,
say, that of the recent landing of Curiosity on Mars?
KOHLHASE: “We were excited that the spacecraft
worked long enough to achieve the first planetary
fly-by, but there were many fewer people then
following the mission. It took time to establish
confidence in the fact that we could successfully
capture scientific results from far-away planets.”
RS: And Mariner 2 did deliver good scientific
observations from both Venus and the
interplanetary environment during the cruise.
Mariner Mars ’69 flyby model used in displaying the Mariner 6 and 7 encounters
with the red planet. Credit: Charles Kohlhase
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KOHLHASE: “It did and from then, as we began to
succeed with each follow-on mission, the press began
to take more interest, especially on Mariner 6 and
7, the first dual mission to Mars in 1969. First, thoug