# 23

Questions d'entretien pour Internship Flight Dynamics Internship partagées par les candidats

## Principales questions d'entretien

Trier: Pertinence|Populaires|Date
On a demandé à un Flight Dynamics Engineer - Mission Analysis...24 mars 2022

### Two satellites are orbiting the Earth in a circular orbit; they are rigidly linked by a tether which is always pointing in the radial direction. What happens as soon as the tether is cut?

1 réponses

The initial motion is circular with angular velocity w0 corresponding to the height of the centre of mass of the two spacecraft. So the satellite above is moving with v_up above the circular velocity for its altitude, while satellite below with v_down below the corresponding circular velocity. As soon as the link is removed, the two satellites are found on their respective apseline (velocity purely transverse), but since v_up &gt; v_circ_up the satellite above is at its perigee, while since v_down &lt; v_circ_down the satellite below is at its apogee. The satellite will move in elliptical orbits which never intersect. Moins

### Given the time history of the range and range-rate of a deep-space spacecraft measured by a ground station, sketch a procedure to infer its right ascension and declination.

1 réponses

The range-rate measure is affected by the GS velocity which produces a Doppler effect, making the range-rate measure oscillate (even if the actual range-rate is constant). The amplitude of the range-rate oscillation is linked to the cosine of the declination (maximum for delta=0, i.e. satellite on Equator), while the right ascension corresponds to that of the GS when the oscillation is null (or +- 90° with respect to the maxima/minima of the oscillation). Moins

### Given three vectors, provide a procedure to define the plane passing through their endpoints.

1 réponses

Take the difference between two couples, then compute the cross product (normal to the plane). One of the three points + this normal vector completely defines the plane. Moins

### You know the position of a spacecraft CoM with respect to a ground station, and also the position of a camera in a spacecraft-fixed reference frame. You also know the attitude of the spacecraft. State which operations are needed to compute the camera position in the reference frame of the ground station.

1 réponses

Composition of a vector rotation (camera relative position rotated in the GS reference frame) and a vector translation (sum camera position with the position of the CoM). Moins

### Cannot remember exactly but do know it was a behavioral interview process.

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