Lunar Mission One

Craft Lander

While our actual space craft will be designed in detail later in the project, we already know what it will need to do, and therefore in principle what it will look like, what it will contain and how it will operate.

Standing about three metres high and weighing about two thirds of a ton before payload or fuel, the Lunar Mission One lander will be launched into space by a medium lift rocket such as a SpaceX Falcon 9. It will be designed to get the mission equipment safely to the Moon, correcting its trajectory at several points before carrying out a staged descent sequence for a precise soft landing. It will feature a built-in propulsion system with one or four main engines, slowing the lander from lunar orbit until final cut-off just above the lunar surface, complemented by several smaller thrusters to point it in the right direction.

The South Pole of the Moon is very rocky and the lander will need advanced navigation techniques to home in to a small landing site about the size of a football stadium.

Equipment and solar power

Once on the surface, the spacecraft will need a range of equipment to support the objectives of the mission. Aside from the drilling system to create the borehole (see below for further details), this will include a jointed robotic arm for handling functions such as manipulating the extracted lunar core samples, and a number of science instruments to analyse the samples and to monitor seismic activity and other local parameters. In all, including the drilling equipment, the lander has to carry about 135Kg of payload, adding about an extra fifth to its weight.

Approximately 0.5-1KW is needed to power the lander’s equipment (less than a domestic kettle!). This will be delivered from solar cells fixed to the sides of the lander. Given the angle of the Moon’s rotation, landing on the rim of a crater (such as the South Pole’s Shackleton Crater) will give the drilling platform the best exposure to constant sunlight throughout its mission.

Drilling on the Moon

In the South Polar Region where Lunar Mission One plans to land, the top 10 metres or so is expected to be made up of a fine-grained surface deposit reworked by constant bombardment of meteorites and smaller particles. Below that is thought to be made up of rocks thrown up by large asteroid impacts with parts fused together by pressure and heat.

Aside from the geology, which is like nothing on earth, there are a broad range of technical constraints and challenges to drilling beneath the surface of the Moon: these include a low mass drill (around 10kg); the absence of cooling liquid; the extreme cold below the surface; the remoteness of the location; and the limited power and forced periods of inactivity during the dark lunar winter.

The drilling operations for Lunar Mission One will use a development of the latest wireline drilling technology in which the complete drill assembly is lowered into the hole by an attached cable. It will anchor itself to the side of the borehole, creating a force for a bottom drill extension to cut a 5cm diameter hole, around a 2.5cm diameter cylindrical core at the centre of the hole. Every 15 cm or so, taking typically an hour to drill, the cable will lift the drill assembly with its core sample to the surface for scientific analysis. The drill will then be returned down the hole to repeat the cycle. A casing or stub tube may be inserted to ensure the stability of the borehole near the surface.

This kind of drill has been prototyped successfully in the USA. To reach operational standards for a real mission, further development work is needed, especially in the design and material of the cutting element, known as the “bit”, and in the remote control software that enables the operators back on Earth to visualise what is going on. These developments are very likely to lead to spin-out benefits for reducing the risks and dangers of remote drilling on Earth.

Once the hole has been drilled to the target depth, the drill assembly will be used to put in place long term borehole monitoring equipment. It will also deliver the time capsules containing the public archive and millions of individual digital memory boxes to the base of the borehole – which will then be plugged.