Combined techniques system engineering

At the price of system complexity, it may be that a combination of techniques offers the most mass-efficient, robust or cost-effective solution (rarely the latter, since complexity usually introduces cost). For example, rather than have a lander descend the last 100 m under retropropulsion, it may make more sense to free-fall from that altitude (requiring less fuel) and instead tolerate a higher touchdown velocity by using some sort of impact attenuator. Similarly, (in the case of landing in an atmosphere), a large parachute may permit a low vertical velocity and thus obviate the need for the terminal braking or airbags that might be needed by a system with a smaller parachute. On the other hand, a larger chute may lead to unacceptable landing dispersions due to greater wind drift during its slower descent.

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