Introduction

• Space exploration and discovery inspires us

• We want and need more of that!

• The high cost is slowing down space exploration

• The challenge to identify the most “valuable” samples to return from the Moon in order to reduce cost … that spoke to us

Overview

• An effective solution is to ensure astronauts land in precisely the location of the most “valuable” samples

• This requires systematic robotic sampling across each large area of “potential value” in order to confirm that value and locate the point of highest value for human landings

Sample pattern - 2 Km intervals: https://gyazo.com/712a1cc4f639372baac7f98564fc1785

How do you do this robotically and keep costs down?

Criteria for low cost

• To bring many samples at low cost to the Lunar Gateway you need:

• Complete reusability

• And a concept to minimize Delta V requirements for each sample

• Smallest feasible size of each sample

• Moving the lowest mass of machinery down the Moon’s gravity well and out again

• Take this to the extreme and you don’t want to move any machinery down to the surface.You only want to bring the samples up to orbit without moving anything down to the surface

Reach down to the surface

• All we need to do is reach down to the surface from orbit and that is more realistic than it sounds

An object is in orbit as long as its center of mass is in orbit.

An object in a 10 Km high orbit only needs to reach down and up 10 Km at the same time to access the surface

https://gyazo.com/d776ff249ad22719a27ce9445413c4b2

Rotate the sampler

• You might say yes but … the sampler is moving horizontally in orbit as well.

The ends of the arms ascend and descend vertically and touch the surface with zero velocity. The path of one arm tip is traced in red: https://gyazo.com/4af5911a9f1469a99f896a2edf4a840e

Low mass arms

• It turns out that commercially available Kevlar thread 20 Km long has enough tensile strength to support this rotation and has a mass of only about 1 Kg

Mission Concept

• A very small space Tug would depart from the Lunar Gateway with the 1 Kg spool of Kevlar and motors to spin up and extend the thread

• The Tug maneuvers to an elliptical orbit with a low point 10 Km directly over the sampling location.The spool is then spun up to extend the thread 10 Km in opposite directions at 1 rev/minute

• The lower arm will contact the surface at zero horizontal velocity, coming in completely vertical, slowing down and re-ascending at 23 G’s. An extremely small sample will be collected on the coated tip

• The Tug will wind the thread in and return to the Lunar Gateway where the sample is collected

Concept benefits

• Low Delta V expenditure

• Complete reusability

• The ability to sample any surface location reachable from the Lunar Gateway

• The vertical approach profile allows sampling of any terrain whether that be highlands or within steep walled craters

Challenges remaining

• Orbit insertion accuracy within 10’s of meters altitude over the target

• Rotational velocity and phase angle control to sample the surface within 100 meters of the target

• Dynamic behaviour of the thread being spun up/down while being reeled out/in