To the Moon on a Shoestring Part 1
Euroluna is financed privately with small funds. We have not received any external financial support. Therefore we have made an effort to keep all investments low. This has resulted in a design that uses both new technologies and old technologies in a new way.
Components are largely based on the Cubesat family and an ion thruster is being used for propulsion. A special strategy for landing on the Moon is under development.
Special software of own design is being used for simulation of trajectories and energy consumption.
Since the cost of launching the spacecraft is largely proportional to the amount of mass of the spacecraft, the spacecraft is light and small. We are aiming for a mass of less than 3.5 kg including the Google Xprize payload.
This puts some constraints on the technology that can be used for propulsion. Chemical thrust was considered but discarded because of the high fuel consumption. Instead electrical propulsion using ion thrust has been chosen.
However, ion thrusters have low thrust. Presently the thrust is in the order of 1 mNewton which means that obtaining the required 3-4 km/s deltaV to get to the Moon takes time. The most economical way in terms of fuel is to only engage the thruster when Romit is close to Earth generating ellipses with eccentricities approaching 1. By this method we can keep fuel consumption as low as 200 grams.
The low weight and cost budgets also dictate that we use very simple means of orientation. We have restricted ourselves to three types of observations.
1. The Earth's magnetic field.
2. Sight (analysis of pictures).
3. The angle to the Sun.
We also have a clock and a number of Moon and Earth ephemerides aboard.
All the observation types have limitations. The current dipole model of the Earth's magnetic field is only good within 3 Earth radii, and the analysis of pictures and the angle to the Sun can only deliver a couple of degrees accuracy.
The best measuring device is the clock, by which we can measure the times when the spacecraft enters and leaves the shade of the Earth and the Moon, and correlate them with the planned trajectory.
In the next blog entry I will go into more detail with the planning of the trajectory.