Human Beings and Automatons

J.S. Mill has formulated a classical statement of the "argument from analogy� concerning knowledge of other minds: "I must either believe them [other human beings] to be alive, or to be automatons� (Mill 1872, 244). It is possible that Wittgenstein had this in mind when writing the following: "I believe he is suffering.�—Do I also believe that he isn"t an automaton? It would go against the grain to use the word in both connexions. (Or is it like this: I believe he is suffering, but am certain the he is not an automaton? Nonsense!) Suppose I say of a friend: "He isn"t an automaton�.—What information is conveyed by this, and to whom would it be information? To a human being who meets him in ordinary circumstances? What information could it give him? (At the very most that this man always behaves like a human being, and not occasionally like a machine.) "I believe he is not an automaton�, just like that, so far makes no sense. My attitude towards him is an attitude towards a soul [eine Einstellung zur Seele]. I am not of the opinion that he has a soul. (PI p. 178) Here Wittgenstein contrasts opinion (Meinung) and attitude (Einstellung). How should this contrast be understood? On a view such as Mill"s, to regard someone as a conscious being is to hold certain beliefs about him, beliefs that can perhaps ultimately be grounded in a theory of some sort. To have an "attitude towards a soul� is, on the contrary, to see a person"s gestures and facial expressions as "filled with meaning�. We have an attitude towards a soul when confronted with a person, which means that we react to his presence and behaviour in a certain way

Feedback stabilization of displaced periodic orbits : Application to binary asteroid

This paper investigates displaced periodic orbits at linear order in the circular restricted Earth-Moon system (CRTBP), where the third massless body utilizes a hybrid of solar sail and a solar electric propulsion (SEP). A feedback linearization control scheme is implemented to perform stabilization and trajectory tracking for the nonlinear system. Attention is now directed to binary asteroid systems as an application of the restricted problem. The idea of combining a solar sail with an SEP auxiliary system to obtain a hybrid sail system is important especially due to the challenges of performing complex trajectories

On the stability of approximate displaced lunar orbits

In a prior study, a methodology was developed for computing approximate large displaced orbits in the Earth-Moon circular restricted three-body problem (CRTBP) by the Moon-Sail two-body problem. It was found that far from the L(1) and L(2) points, the approximate two-body analysis for large accelerations matches well with the dynamics of displaced orbits in relation to the three-body problem. In the present study, the linear stability characteristics of the families of approximate periodic orbits are investigated

Displaced solar sail orbits : dynamics and applications

We consider displaced periodic orbits at linear order in the circular restricted Earth-Moon system, where the third massless body is a solar sail. These highly non-Keplerian orbits are achieved using an extremely small sail acceleration. Prior results have been developed by using an optimal choice of the sail pitch angle, which maximises the out-of-plane displacement. In this paper we will use solar sail propulsion to provide station-keeping at periodic orbits around the libration points using small variations in the sail's orientation. By introducing a first-order approximation, periodic orbits are derived analytically at linear order. These approximate analytical solutions are utilized in a numerical search to determine displaced periodic orbits in the full nonlinear model. Applications include continuous line-of-sight communications with the lunar poles

On the stability of displaced two-body lunar orbits

In a prior study, a methodology was developed for computing approximate large displaced orbits in the Earth-Moon circular restricted three-body problem (CRTBP)by the Moon-Sail two-body problem. It was found that far from the L1 and L2 points, the approximate two-body analysis for large accelerations matches well with the dynamics of displaced orbits in relation to the three-body problem. In the present study, the linear stability characteristics of the families of approximate periodic orbits are investigated