## 6 Conclusions and Future Work  
This paper follows the Electric Sail Mission Expedition (ESME) [42] as the second in a series on E-sail demonstration in the solar wind. We have proposed a 2 km tether charged at 20 kV to achieve the propulsive E-sail force of 1 mN by placing a 15 kg 2 \(\times\) 4 U cubesat in lunar orbit. The E-sail force can be estimated by generating the thrust and the torque in two experimental modes. When the E-sail spin plane is perpendicular to the solar wind and charged either when moving towards or away from the Sun, within three days, we can create the change in orbital period of 100 s, which should be estimated with the ranging experiment. We can also observe the E-sail tether coming motion with the tether camera. The tether motion can be used to estimate the E-sail force and to characterise E-sail behaviour. When the E-sail spin plane is parallel to the solar wind and charged either when rotating towards or away from the Sun, we can achieve the change in angular velocity of more than 1 deg /s. Langmuir probes are proposed to characterise the E-sail plasma environment. This paper proposes novel navigation and communication solutions without access to space agencies' deep space networks. Future work includes a detailed analysis of all aspects of the ESTCube-LuNa. A summary of our proposed method is as follows:  
1. Integrate the ESME thrust and spacecraft attitude dynamics with DOCKS in order to simulate generic E-sail experiments and missions with a high-fidelity numerical orbit propagator. 2. Integrate the ESME tether dynamics with high-fidelity attitude control for tether deployment. 3. Refine the escape manoeuvre and develop other trajectory options by integrating realistic spin plane change abilities: either with E-sail or with thrusters on a remote unit. 4. Develop ESTCube-LuNa trajectory options with a fixed spin plane. 5. Refine the design of experiments, payloads and estimate the E-sail tether length with real-life experiments: how much tether can be hosted on a reel with an automated tether factory? 6. Develop deep space communication and ranging nanospacecraft solutions for which there are no European transponders. 7. Develop navigation and attitude determination systems and algorithms. 8. Develop attitude control systems and algorithms. Figure 14: The ESTCube-LuNa real-time 3D (RT3D) navigation concept in Unreal Engine 5 with textures from the Solar System Scope [61]. The image on the left shows the Moon; on the right, the Sun and the Earth, as imaged by two out of five 120\({}^{\circ}\) FoV cameras. By imaging three celestial objects, triangulation can be used to determine the ESTCube-LuNa position in lunar orbit, as described in Section 5.5.2. Continue developing the real-time 3D modelling environment. * Develop a remote unit technology concept for a potential ESTCube lunar escape mission concept with optimal thruster placement for E-sail spin plane control. We see this as the primary showstopper for implementing the lunar escape manoeuvre, as proposed in Section 4 with modelling details described in the work of [PERSON] et al. [42]. In terms of launching ESTCube-LuNa, the European Union's IOD/IOV programme, as well as the European Space Agency's \"Small Missions for Exploration-Destination the Moon\", suggests Ariane 6. While the ESA call is not suitable for the ESTCube-LuNa concept, the IOD/IOV programme has already supported the ESTCube-2 LEO launch and can potentially support the ESTCube-LuNa launch, given funding opportunities from elsewhere. The specific orbit depends on a specific rideshare opportunity, with which the potential ESTCube-LuNa mission would need to be aligned. Conceptualization, A.S., M.F.P., J.D., P.J., M.T., N.I., G.P., M.B. ([PERSON]), M.D., J.K., J.V., P.H., J.S., E.B., M.A., H.T., K.A. ([PERSON]), A.V., L.N., M.B. ([PERSON]), G.M., P.T., I.I. and M.P. ; Methodology, A.S., M.F.P., P.J., N.I., A.R., K.A. ([PERSON]), A.M., N.O., K.M.M., S.K., G.P., M.B. ([PERSON]), M.D., I.O., J.K., T.E., V.A., J.V., P.H., K.K., J.S., E.B., M.A., H.T., K.A.