Preparing for the unexpected: a second way to sample a moon

No one has ever visited the moons of Mars. Exactly what these two small worlds are like is therefore a mystery. This presents our Martian Moon eXploration (MMX) Mission with a major challenge: successfully gathering a sample of soil from unknown terrain and returning it to Earth.

Group photo from the visit to HBR (left: HBR, right: JAXA)

To tackle this situation, our engineering team has examined observational data of the two moons, and experimented with different sized grains and textures of sand. We saw these tests in action in our blog post on July 19th, where the spacecraft’s corer was being designed to bore into the surface of the moon.

However, space exploration rarely goes 100% as expected. Our sampling system must therefore be designed to cope with a surprising find. For example, imagine a situation where only a small layer of loose soil sits on the moon’s surface above a much harder bedrock. The spacecraft’s corer would be unable to pierce the hard ground, making it much more difficult to collect a soil sample. Just in case this occurs, we are determined to be prepared. What is needed is an additional method to gather a sample.

In April 2016, we talked to Honeybee Robotics (HBR) in California, USA. HBR are the designers of the sample technology used in a number of NASA missions. Based on their abundant experience, it was decided that a pneumatic system, which uses an air gun to puff pressurised gas, could push soil into the sample container even in the presence of a hard bedrock. With the design teams now straddling two countries, the new challenge became to design a straight-forward installation and sample collection method.

From input/output nozzles to In-N-Out Burger.

For about a year, HBR and JAXA explored how to install a pneumatic sampler. In August 16 – 17th 2017, we visited HBR to discuss the installation onboard the MMX spacecraft face-to-face. We realised that the installation could be simplified by modifying the design to allow equipment to be shared with our main sampling system. With this in place, we were next able to establish a robust system for operation!

HBR is an energetic company with excellent young technicians. They noted that the sample size could be increased by careful design of the nozzle on the pneumatic sampler. The optimal shape of this inlet and outlet is found by performing multiple experiments. During our visit, we were invited to the appropriately named hamburger chain, ‘In-N-Out Burger’. We will definitely do our best to gather a large sample from the Martian moons, as the popular ’In-N-Out Burger’ gathers a large number of customers!

(Based on the article in Japanese by Yasutaka Satou from the Department of Space Flight Systems at ISAS/JAXA)