Viking '75 Mars Lander Surface Sampler Collector Head

For the past few years I’ve been working on a long-term project to re-create the Viking '75 Mars lander unmanned spacecraft as a high-fidelity SketchUp model. The most recent portion to be completed is the Surface Sampler Collector Head or “scoop” that was used to dig up samples of Mars soil and deposit them into the lander’s science instruments for analysis:

The model has a fairly complete “working” interior that supports all the operations of the actual unit:

An exploded view:

The model has been uploaded to the 3D Warehouse for others to use as they see fit. All the components are solid and in principle able to be 3D-printed, though many have realistically-thin wall sections that would likely be a challenge. Other renderings of the work-in-progress model show my gradual progress. A few years of effort remain! :slight_smile:


That’s very impressive work.

I checked out the other renderings and you’ve already done an astounding amount of highly detailed work on this project.

What is the basis of your sustained interest and incredible dedication to this project?

It’s a labor of love. I’ve been a space-program enthusiast since I was a kid in the 1960s; the earliest missions that I recall were the Gemini flights. I followed the Apollo program rabidly. I was in high school during the Viking '75 missions. For a hobby I was a model-maker back then, and began a 1/20th scale Viking lander from scratch. I never got very far before college intervened. I still have the parts of that Viking model. In the subsequent decades I always smiled whenever I came across a Viking reference. About six years ago a visit to the Smithsonian National Air and Space Museum in Washington DC allowed me to see the Viking Proof Test Capsule (PTC) lander on display. That re-kindled my Viking passion in a big way.

In the past few years I’ve been fortunate enough to conduct detailed personal examinations of most of the extant major Viking lander hardware (capturing over 3,000 detailed photographs and ~1,000 measurements). This includes the Proof Test Capsule lander at the Smithsonian; the backup Flight Capsule 3 lander owned by the Viking Mars Missions Education and Preservation Project (VMMEPP) and exhibited at The Museum of Flight in Seattle; what was the Science Test Lander, now at the Virginia Air and Space Center; another test lander at the California Science Center; a spare surface sampler (subject of this forum topic) and Collector Head Shroud Unit at the NASA Langley Research Center; plus a few other hardware pieces owned by the VMMEPP and others such as a High Gain Antenna and an X-Ray Fluorescence Spectrometer.

I’ve collected historic photographs, drawings and diagrams, plus a set of lander body assembly blueprints.

All the photos and measurements I’ve captured are in public Google Photos albums (a few links in-line above), for those who may be interested. My SketchUp model components are also publicly available, some in the 3D Warehouse and everything in a DropBox folder. I’m in my 50’s now, and hope that my brain and eyesight holds out for a few more years to complete the lander digital re-creation project. The Viking missions were incredibly ground-breaking then (and even now in many ways), and deserve to be preserved and remembered.

Edited to add two videos that bring this back to SketchUp: a Making-Of video and an animation of the Viking lander’s legs.


So you’re a total space geek then - that explains it!

Seriously though, I think very few people would have the tenacity and endurance to embark on such an ambitious undertaking. I’m thoroughly impressed with the depth of your research and the extensive resources you’ve gathered over the years.

I appreciate that you’re making it publicly available. It’s a real treasure trove and a valuable resource for anyone that holds similar interests.

Thanks for explaining… and for sharing your amazing project.

Brilliant!! :rocket:

Tom ; Great looking model.
I was a member of part of flight team ( LPAG ) at the SFOF and one duty that night for the first landing and in fact have the first pictures returned at landing. They are not what most people think but, actually pictures of one of the landing foot pads because at that time there was concern abut dust on the surface and the landing site would be disturbed.
The PTC was used during mission operation to verify command uploads. We had to project some time ahead what affects it would have in the future as far as actual system operation. Uplink command rate was a whoopng several bits a second at that time in the space program

Hi Mac1, it’s amazing that you were part of the Lander Performance Analysis Group! I bow to you. Oh the documentation and knowledge that you must have once held… I was living in Madison WI on July 20 1976 when Viking 1 landed and transmitted the first image of footpad 3. I recall watching live on TV as the vertical image strips came in gradually, at first a narrow meaningless gray pattern, then - rocks! And then the footpad, wow. I had the pleasure of meeting some Vikings at the 40th anniversary event in Denver CO this past July, where I had a table showing my 3D model and research materials.

E-mail me and will post info for you in my drop box if I find some thing that looks of interest and wiil not bother folks in this forum.
Design cadre has thinned out quite a bit in last few years:sob:.
BTW Littleton museum has been collecting info from retirees via the MARS retirees org. for several years maybe they would have some info for you.
Good luck with you effort

Wow! That is incredible! Congratulations!

I was browsing the gallery and came across this. This is extraordinary. Not that I am an expert at all, but the presentation is sublime and the colour presentation and shading is just beautiful in the way that it so clearly demonstrates the inner workings and exterior. As for the subject - out of this world!

Fantastic work! A labour of love indeed. If this were your job, I bet the quality would only be half as good. Just brilliant!!

Keep it up and keep us posted.

Hi Rightangler and Scooter, thank you for the kind words and encouragement. The latest portion of the model to be completed is the surface sampler’s hollow furlable boom or arm; the Flat Conductor Cable (FCC) that runs through the center of the boom; and the hardware used to attach the collector head to the boom. Here is an overall view and some comparisons between renders of the model and actual Viking hardware:

And here are some cut-away and exploded views, showing the 26-conductor FCC (a few inches of curled slack and a spring clamp are used to maintain tension):

Here is a version depicting a short section of the boom illustrating how it flattens when retracted, enabling the boom to be wound up on a drum. The boom is actually about 12 feet long, ten feet of which can be extended out of the housing or canister into which it is stored. For this rendering I truncated the boom quite short, revealing the FCC that extends out the inner end of the flattened boom.

I am currently working on modeling the articulated housing into which the boom retracts. It’s a complex mechanism itself. To date I’ve nearly completed the right and left side frames. Thin sheet metal panels, yet to be modeled, are attached in most of the various openings in the frames. The boom will eventually extend out through the vertical face (between side frames) on the far left:


A bit more progress has been made on the Surface Sampler Acquisition Assembly (SSAA) housing, completing the eight frames comprising the housing structure:


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.