Viking '75 Mars Lander Surface Sampler Collector Head

Wow, that’s an unbelievable level of detail. Nice work.

Next installment of progress: the azimuth and elevation drive assemblies for the Viking lander’s surface sampler’s housing (which would sit atop these mechanisms, and is depicted in earlier replies). The gear train for the azimuth drive (horizontally-arranged gearing, on the left) is based on a drawing of the actual hardware though the tooth counts and dimensions are estimated. The vertically-oriented elevation drive has an approximately-correct fixed worm-wheel gear, but the spur and bevel gears inside the little gearbox are speculative due to lack of reference documentation. The gear tooth profiles are simplified. The large cylinder is a very rough model of the drive motor for the elevation axis.


Next up are the components of the boom extend-retract drive mechanism and the boom stowage drum for the lander’s Surface Sampler Acquisition Assembly, in approximate form due to lack of detailed reference material (as denoted by the green tint). The hollow interior of the large drum contained a few feet of the Flat Conductor Cable (FCC) that runs through the middle of the boom (not shown here, but see earlier replies for renderings of it). This slack allows the boom to extend and retract by ten feet, as the slack within the drum is wound clockwise around the stationary hub when at one end of full travel, and re-wraps to be counter-clockwise around the hub by the time the other end of travel is reached. The flattened boom itself wraps around the exterior of the drum. The large slot in the drum (visible in the second image) allows the FCC to pass from the boom into the drum, and the slot in the hub (partly visible in the first image bracketed by curled bend-limiter fences) allows the FCC to exit the assembly through the center of the hub (coming out on the side visible in the third image).

Here is an original 1970’s drawing of the hardware from Martin Marietta (who built the lander) that I’ve been using to model the internal components. The design seen in this drawing is of a not-quite-final version of the unit.


I’ve finally completed the Viking '75 Mars lander Surface Sampler Acquisition Assembly, which is now available in the 3D Warehouse.

The final set of components to be modeled were the boom supports and guides:

Here are the support guides fitted to the surface sampler:

Here is the unit in place on the overall (work-in-progress, very incomplete) Viking lander:


This is fascinating. Thank you for sharing your work.

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For the past couple of months I’ve been working on a video that describes how the Viking lander’s actual surface sampler hardware works, using my SketchUp model for much of the presentation. Here is a short clip showing the parts of the collector head being assembled together. The animation was done with Fredo6’s Animator extension.
- Tom


Very cool! First, it’s amazing that everything about your model looks more like a Fusion 360 project than a SketchUp project. Second, I’ve been curious about Fredo6’s Animation extension, and I think you just convinced me to try it.

Just plain Brilliant!!

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Wow these models are amazing, how much more do you have to do before it’s completed?

Hi Liam, there is a great deal remaining to do! It’s not quite half complete. At the pace I’ve been going, probably another five or six years. I started the overall model (of which this Surface Sampler is just a small portion) almost exactly four years ago; the surface sampler took eight months of my evenings etc. I started serious research in 2011.

I occasionally detour myself into side projects. For example during the past three months I’ve been working on a video explaining how the surface sampler works. About 12 minutes of that “documentary” are done, with three or so more to go. I’ll post a link here when the video is ready.


Oh well keep it up it’s going to be great when it’s finished worth all of the time put in!

I have completed a detail video (nearly 18 minutes long) that demonstrates how the Viking '75 Mars lander’s surface sampler operates. The demos are done with my SketchUp model. Most of the animation was created using @Fredo6’s Animator extension. Two of the scenes (unwinding of the flat conductor cable, and backhoe trenching) were created with @Anton_S’s MSPhysics extension.


Wow! Awesome piece of work.

I think @TDahl should be invited to the next SketchUp Basecamp as a presenter, all expenses paid.

Thanks for uploading and sharing this video, I thoroughly enjoyed it.


Tom Dahl, this is one of the best pieces of work I ever seen!

The level of engineering and sophistication put into the viking lander is absolutely astounding!

Great work!

Absolutely brilliant! I’ve previously expressed my admiration for your effort in recreating the lander and it’s subsystems, and the dedication, quality and tenacity with which you’ve pursued each aspect.

But this takes it an extra step further. The advanced animation skills you’ve gained, when applied to the highly detailed mechanisms (modelled with such fidelity) — and some fine video production quality — combine to make the workings of this very complex machine crystal clear …even to a layman. (me!)

Congrats on producing such a successful result. Really astounding, educational and inspirational stuff!

I watched this with my jaw dropping at the detail of the drawing, the quality of the animation, and the clarity of narrative.

Superb. Thank you SO MUCH for sharing it.

This is one of the best Sketchup models I have ever seen!

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I’m absolutely floored at not only the level of detail and complexity you have created in the model, but how well thought out and comprehensive your explanation is. This is stunning work, thank you!

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Thank you for the compliments, folks - much appreciated!

I have shared the video with one of the chief designers of the Viking surface sampler (at Martin Marietta Aerospace near Denver) and with the sampler team leader during Viking’s primary mission (he was a NASA Langley Research Center employee; Langley was the home of the Viking Project Office). It’s a privilege to be in contact with them (and they enjoyed the video too :slightly_smiling_face:).