Viking '75 Science Test Lander, Detail photographs of the Science Test Lander from Viking '75 Options

[Tom Dahl]

Recently I spent an enjoyable afternoon photographing the Viking '75 Mars Lander
which is on display at the Virginia Air and Space Center in Hampton VA. Based on
many details, I am sure this is the so-called Science Test Lander (STL) which
was installed in the NASA/JPL "sandbox" during the missions. I have uploaded 277
detail photos (totaling nearly 2GB) to a Picasa Web album.

(As far as I know, the best/only way to download them all is to install and
execute Google's free Picasa application for Windows PCs. Note a quirk with the
Picasa Web magnifier tool: on large images such as these, the full resolution
usually is not loaded right away when you activate the magnifier. If you wait
ten seconds or so, usually the full 4K-pixel version will become available via
the navigator pop-up in the corner. Sometimes it never does, however.)

The STL in its current museum display configuration has two very interesting
attributes. First, the insulation blankets and cloth covers which normally
surround the fuel tanks, associated plumbing, and roll-control thrusters has
been removed. I happily captured a fair number of photos of the exposed (and
complex!) fuel-system plumbing, valves, wiring, and thrusters.

Second, the lander's bottom cover plate has been cut open in the 30-inch square
area normally covered by the Terminal Descent Landing Radar (TDLR) box. The TDLR
is not installed; instead it is mocked-up on two side with tall white flanges. I
would like to see an accurate TDLR someday (the Smithsonian's Proof Test Capsule
is also missing a TDLR), so it's a bit of a shame not to find one here. However,
the trade-off is wonderful -- the large opening in the bottom allows a peek at
the lander's interior! It is not really possible to see visually inside, due to
geometry of the museum display, but a carefully-positioned camera can get some
views. :-)

The STL body is essentially empty, but a few interesting details are present.
The dacron-covered insulation blankets lining the interior sidebeam walls are
there, restrained with authentic vertical nylon ties. The Equipment Plate is
installed, which is a large hexagonal aluminum plate spanning the interior about
five inches down from the lander's top cover plate. (The computer, batteries,
science instruments, radios, etc. were bolted to and hung from the bottom of the
Equipment Plate.) The plate is partially painted black (for thermal control) in
areas which were not to be covered by mounted components, and this is visible.
The thin coolant-loop tubing which snakes around the underside of the Equipment
Plate is there. The three cylindrical struts from which the TDLR was to be hung
are there. The Thermal Switches to which the Radioisotope Thermoelectric
Generators were mounted are there, and I managed to capture a peek at the
flexible copper "Contactor" of one of them.

The STL has somewhat simplified external wiring, and the externally-mounted
electronics units on sides 1 and 3 are simple wood mock-ups. This includes the
Inertial Reference Unit, the two Radar Altimeter Electronics units, and the
Valve Drive Amplifier. The three Terminal Descent Engines are also mostly wood
mock-ups, however TDE #2 (on the "front") has an authentic top plate and gold
thermal shield.

I was able to take a number of detail measurements, which will eventually be
incorporated into plans I've barely begun to create. All in all, I was very
happy to have made the trip to see this lander.
-- Tom