Mission Design for the CubeSat OUFTI-1

CHAPTER 5.MISSION ANALYSISIn figure 5.12 the true, eccentric and mean anomaly are represented: as theorbit is elliptic, they have different evolutions.Figure 5.12: OUFTI-1 orbit: true, eccentric and mean anomaly as a functionof time over a periodJust to have an idea of the possible circular orbit at 350 Km altitude, acomparison is reported in table 5.1.Table 5.1: Comparison between the two possible orbits350x1200 Km 350x350 KmSemi-major axis a (Km) 7153.14 6728.14Eccentricity e 0.0594 0Energy E(Km 2s 2 ))-27.8 -29.6(Perigee speed v Kmp(7.922 7.697sApogee spped v Km)a 7.034 7.697sPeriod T (min) 100.35 91.53The most important difference between the two orbit is the speed: in fact,in order to have a good communication, we would like to have a satellite passingover the ground station as slowly as possible. This reduces in fact the dopplereffect and, even more important, increases the time during which the satelliteis in the the ground station’s field of view.As the link budget guarantees a sufficient signal-to-noise level at 1200 Km altitude(seechapter 10), we prefer the elliptic orbit with the apogee over thenorthern hemisphere at the mission’s beginning.Galli Stefania 39 University of Liège