Earth Delivery of a Small NEO with an Ion Beam Shepherd

The possibility of capturing a small Near Earth Asteroid (NEA) and deliver it to the vicinity of the Earth has been recently explored by different authors. The key advantage would be to allow a cheap and quick access to the NEA for science, resource utilization and other purposes. Among the different challenges related to this operation stands the difficulty of robotically capturing the object, whose composition and dynamical state could be problematic. In order to simplify the capture operation we propose the use of a collimated ion beam ejected from a hovering spacecraft in order to maneuver the object without direct physical contact. The feasibility of a possible asteroid retrieval mission is evaluated.

Relative Dynamics and Control of an Ion Beam Shepherd Satellite

The ion beam shepherd (IBS) is a recently proposed concept for modifying the orbit and/or attitude of a generic orbiting body in a contactless manner, which makes it a candidate technology for active space debris removal. In this paper we deal with the problem of controlling the relative position of a shepherd satellite coorbiting at small separation distance with a target debris. After deriving the orbit relative motion equations including the effect of the ion beam perturbation we study the system stability and propose different control strategies.

The SIROCO Asteroid Deflection Demonstrator

There is evidence of past Near-Earth-Objects (NEOs) impacts on Earth and several studies indicating that even relatively small objects are capable of causing large local damage, either directly or in combination with other phenomena, e.g. tsunamis. This paper describes a space mission concept to demonstrate some of the key technologies to rendezvous with an asteroid and accurately measure its trajectory during and after a deflection maneuver. The mission, called SIROCO, makes use of the recently proposed ion beam shepherd (IBS) concept where a stream of accelerated plasma ions is directed against the surface of a small NEO resulting in a net transmitted deflection force. We show that by carefully selecting the target NEO a measurable deflection can be obtained in a few weeks of continuous thrust with a small spacecraft and state of the art electric propulsion hardware.

1794, Catalogus eorum qui in Universitate Harvardiana, Cantabrigiae, in republica Massachusettensi, ab anno MDCXLII, ad annum MDCCXCIV. Alicujus gradû laureâ donati sunt.

Modern hardcover binding around original handsewn paper binding. Missing title page and first page of text. Key to abbreviations titled "Explination" on flyleaf with abbreviations for Massachusetts, New Hampshire, Connecticut, Rhode Island, Long Island, New York, Martha's Vineyard, New Jersey, Pensylvania [sic], Virginia, South Carolina, Georgia, West Indies, Great Britain, Episcopalian, and Baptist. Heavily annotated with residence locations. Asterisks added next to the names of alumni who died after the Catalogue's publication, generally in 1795. Also includes a tipped-in page at front of volume with the names of thirteen alumni of various classes from 1650 through 1756, in one hand, a note "Joseph Lovett was of Beverly, and a minister in a town of Connecticut the name of which I do not recollect. JW" in a different hand, and a final note "I believe there was a Lovett at Norwich" in the original hand.

Letter from Artemas Ward to Benjamin Stone, 1787 July 18

Artemas Ward wrote this letter to Benjamin Stone on July 18, 1787, expressing his concern about the expense of his son, Henry Dana Ward's, imminent studies at Harvard. Ward complains to Stone about his own debts and the failure of the government to honor their financial obligations to him, and he also expresses hope that the President of Harvard will allow his son to spend part of his time "keeping a school" during his freshman and sophomore years, thus earning an income sufficient to pay for his studies. Ward also suggests that it might be preferable that his son board with a respectable family, rather than live at the College.