**4. Overall mission specification**

The Mars entry flight is described assuming a point mass model, starting from a low circular orbit. The orbit condition implies the equilibrium between centrifugal and gravity force, see **Figure 2**, given by *Fc* <sup>¼</sup> *mv*<sup>2</sup> *<sup>r</sup>* and *Fg* <sup>¼</sup> *<sup>G</sup> MMarsm <sup>r</sup>*<sup>2</sup> :

$$G\frac{M\_{\text{Mars}}m}{r^2} = \frac{mv^2}{r} \tag{1}$$

where *<sup>r</sup>* <sup>¼</sup> *RMars* <sup>þ</sup> *<sup>h</sup>*<sup>0</sup> and *<sup>G</sup>* <sup>¼</sup> <sup>6</sup>*:*<sup>673</sup> � <sup>10</sup>�<sup>11</sup> *Nm*<sup>2</sup> *kg* , being *RMars* the planet radius and h0 = 120 km the entry altitude.

Using the geometric data for the vehicle, the initial entry speed from Eq. (1) can be obtained:

$$V(t\_0) = \sqrt{\frac{G \bullet M\_{\text{Mars}}}{R\_{\text{Mars}} + h\_0}} = 3484 m/s \tag{2}$$

Initial flight path angle *γ*<sup>0</sup> is an important design parameter for entry vehicles. For the sake of simplicity, the other initial conditions are chosen as follows:

$$\chi(t\_0) = \mathbf{0} \; rad; \theta(t\_0) = \mathbf{0} \; rad \varphi; (t\_0) = \mathbf{0} \; rad \tag{3}$$

It is supposed that below *M*<sup>∞</sup> ¼ 2 a supersonic inflatable decelerator performs the final deceleration to the terminal landing speed and a paraglider allows the touchdown.
