Use of Spacecraft Swarms to Characterise Asteroids during Flyby

Of the more than 700,000 asteroids known today, only 12 have been visited by spacecraft. This means that many assumptions about their characteristics remain unverified. Various swarms of spacecraft have been suggested for characterising asteroids. The development of these spacecraft swarms could improve the versatility of these missions and increase the number of asteroids visited. In this thesis, two novel swarm flyby strategies are created that build upon previous spacecraft swarm development. The first of these strategies uses the relative dynamics of a swarm to estimate an asteroid’s mass. Analytic equations are created and verified using numerical analysis for this estimation. It is found that this technique can be implemented for asteroids more massive than 1×〖10〗^18 kilograms, roughly the size of 21 Lutetia. A swarm of three or more spacecraft can also allow for the passing distance of spacecraft from the asteroid to be estimated simultaneously. However, this can result in errors greater than 10% if flyby conditions are not carefully controlled. It is also found that the relative dynamics between swarm spacecraft allow for the absolute swarm orientation to be determined, although this option is unattractive when mission operations are considered. The second strategy sees a swarm of spacecraft in orbit around the Earth waiting for an asteroid to pass close before moving out to meet it. Data from 2016 is used to find how many were accessible to the swarm using analytic orbit analysis. The probability that a spacecraft would lie at a position on the holding orbit where it could reach an asteroid for a given ΔV is used to make a decision on whether to transfer. From this data, up to five asteroids could be visited from High Earth Orbit with a ΔV of less than 1 km/s per asteroid. More asteroids are likely to become accessible using this method if new observation techniques are employed. The use of swarm spacecraft to estimate asteroid mass reduces dependence on Deep Space Network antennas. A swarm can make its estimation using a limited number of sensors, although they must be repeated across several spacecraft. Finally, a large number of asteroids can be visited each year if a swarm of spacecraft is placed in Earth orbit and used to visit close-passing asteroids