Goal

Within NASA’s Mars Exploration Program, Mars Sample Return (MSR) has fast become a point of focus. The Mars 2020 mission will deposit sample tubes on the surface of Mars to collect samples for eventual return to Earth. Following the Mars 2020 mission, there will be two further missions: a lander and an orbiter. The lander will comprise of a fetch rover to retrieve the sample tubes and a Mars Ascent Vehicle (MAV) to launch the collected samples into Mars orbit. The orbiter will capture the canister containing the sample tubes and return it to Earth. This paper proposes a design for inserting the loaded sample canister into the Orbiting Sample (OS), securing it for launch and releasing it from the insertion mechanism.

Design

Translation Design

Rotation Design

Overall Design

Designs were created in SolidWorks based on some hand calculations and force and tolerance analyses. Short lead time parts were sourced and incorporated into the design too.
The images show each of the modules that were designed and combined.

Moment Calculations

Disconnection

Manufacturing and Assembly

The design outlined was assembled. When running the mechanism, a 3D-printed physical hardstop was also integrated to prevent the canister from being rotated beyond the horizontal (the alignment for insertion to the OS) as well as some other "on the fly" adjustments for manufacturing / assembly feasibility.

In testing the mechanism, there was a successful sequence of a rotation, translation and release. The system was never tested with the actual OS because, at the time of testing, it was in use elsewhere on Lab. 
During testing, large amounts of vibration occurred in the speed reducer. This was likely due to stiction occurring between the teeth in the worm gear and was exacerbated by the cantilever over the output shaft. By tuning the motor properly and better aligning the output shaft of the motor and the input shaft of the gearbox, some of these vibrational effects might be reduced. Furthermore, during this initial testing, the worm gear was totally unlubricated: oiling the gear will likely allow it to run more smoothly and with a less jerky motion. The speed reducer must be flipped from its current orientation in order for it to be oiled (oil would spill out in its current configuration): this will induce some other geometric changes too.

​A preliminary design for a mechanism to insert the canister into the Orbiting Sample (OS) for the Lander portion of the Mars Sample Return (MSR) mission was proposed and implemented. Although there was success in testing, there are many areas of potential improvement to be explored. Furthermore, in order to complete the full specifications of the canister insertion, a 100 Newton-meter motor must be integrated for securing the canister in the OS and automatic motor control ought to be incorporated.

Final Assembly