## 2 Aims and Objectives
### Mission Statement and Payload  
The developed sub-systems will power a 3U CubeSat, with an experimental payload capable of measuring Earth's radiation imbalance using Vertically Aligned Nanotubes as a Radiometer assessment, commonly referred to as RAVAN by NASA. Measuring Earth's radiation imbalance is key to predicting climate change for the coming decades [9], data generated by the mission will be vital in influencing the reduction of pollution from manmade sources and helping Engineers/Geographers prepare for the warming effects potential impacts. The phenomenon of climate change is due to change in Earth's energy budget. This is a delicate balance between incoming solar energy entering Earth's atmosphere and opposing reflected solar and thermal radiation leaving the atmosphere [22]. A negative balance would have a cooling effect on the world's climate whereas a positive budget would cause energy accumulation raising the temperature within the atmosphere, a trend which is widely accepted by society. It is currently estimated that Earth's radiation imbalance is around 1 W/m\({}^{2}\) causing the warming effect [22]. This value is attained mainly using satellite observations and tracking ocean temperature values. It is also widely accepted that imbalance is driven by increased greenhouse gas emissions from human sources [9]. The value of incoming solar radiation is relatively stable, estimated at an average integrated value over the atmosphere of 340.20 \(\pm\) 0.12 W/m\({}^{2}\)[22]. The purpose of this experiment is therefore to measure the total outgoing radiation (TOR), this value alters significantly at different global regions. Recent satellite observations globally and mathematical models state the energy radiation imbalance can range from \(-\)2 to \(-\)7 W/m\({}^{2}\), showing a large variation to the estimated value of 1 W/m\({}^{2}\). The satellite equipment used to measure values of TOR is outdated and inaccurate. Recently developed RAVAN technology for nanosatellites can measure TOR to an accuracy of 0.5 W/m\({}^{2}\) providing a much more accurate estimation of globally altering TOR values [9]. This data is pivotal to tackling and monitoring the issue of global warming and acts as significant justification for the launch of this CubeSat. Ideally a constellation of nanosatellites orbiting Earth would build up an accurate global network of real time data for TOR values as shown in Figure 1. A constellation of satellite would be of huge expense; it is, therefore, required that the selected propulsion system is widely available and cost effective as estimates suggest at least 40 satellites would be needed. Figure 1: Proposed Constellation of CubeSats measuring Earth’s energy imbalance [9]. The CubeSat's orbit will be a near circular Sun-synchronous low Earth orbit at an altitude of 600 km, with an inclination of 98 degrees [9]. The RAVAN system measures Earth-leaving fluxes and incoming solar radiation mainly from the Sun's rays using two technologies. It utilizes vertically aligned Carbon nanotubes (VACNTs) to create a radiometer absorber. Carbon nanotubes have one of the lowest spectral responses over an extensive wavelength range known to man. This is combined with a gallium black body. This acts as a calibration device for the sensor [9]. Carbon Nanotubes are hollow cylinders constructed of graphene. When aligned in a forest configuration (See Figure 2) they become one of the blackest structures available to engineers. A forest is mostly an empty hollow space, acting as a photon trap. With regards to space exploration, they are compact, mechanically able to withstand stresses and do not produce gas meeting CubeSat specification launch requirements. The second significant component of the experimental payload is the Gallium black body calibrator. Two gallium bodies are attached to sensor head contamination covers (see Figure 3). These bodies are infra-red sources used in conjunction with deep space looks to determine a constant reference calibration value.