Which of these burns is retrograde in bi-elliptic transfer?

First burn

Second burn

Third burn

Fourth burn

Correct Answer : Third burn

Explanation : The third burn is retrograde i.e. the burn is opposite to the direction of the motion. This is done to slow down the object and circularize the orbit by lowering the perigee to the final orbit’s radius.

Recently Updated in Spaceflight Mechanics Questions

Where does the smallest possible transfer ellipse occur for a Hohmann transfer?

Equator

Only apogee of the final orbit

Only perigee of the final orbit

Perigee and apogee of the final orbit

Correct Answer : Option (D) : Perigee and apogee of the final orbit

Explanation : When there is a Hohmann transfer, the smallest possible transfer ellipse occurs when the transfer takes place at either apogee of perigee of the final orbit which is at a point opposite to the terminating point.

When both initial and final orbits are circular, what is the maneuver known as?

Chase maneuver

Bi- elliptic transfer

Hohmann transfer

Phasing maneuver

Correct Answer : Option (C) : Hohmann transfer

Explanation : When the initial and final orbits are circular, the optimal maneuver is called a Hohmann transfer. This transfer consists of two tangential velocity impulses which I applied at the initial and final radius.

In which case is the minimum velocity impulse achieved for coplanar maneuver?

When impulse is applied radially

When impulse is applied at 45 deg

When impulse is applied tangential

When impulse is applied perpendicularly

Correct Answer : Option (C) : When impulse is applied tangential

Explanation : For a coplanar maneuver, multi-impulse maneuver is very efficient. The minimum velocity impulse is achieved when the impulse is applied in the same direction of initial and final velocity vector. This is known as tangential impulse.