During the 1970s members of the British Interplanetary Society embarked on a landmark theoretical engineering design study to send a probe to Barnard's star. Project Daedalus was a two-stage vehicle employing electron beam driven inertial confinement fusion engines to reach its target destination. This paper sets out the proposal for a successor interstellar design study called Project Icarus. This is an attempt to redesign the Daedalus vehicle with similar terms of reference. The aim of this study is to evolve an improved engineering design and move us closer to achieving interstellar exploration. Although this paper does not discuss prematurely what design modification are likely to occur some indications are given from the nature of the discussions. This paper is a submission of the Project Icarus Study Group.
Deep Dive into PROJECT ICARUS: Son of Daedalus, Flying Closer to Another Star.
During the 1970s members of the British Interplanetary Society embarked on a landmark theoretical engineering design study to send a probe to Barnard’s star. Project Daedalus was a two-stage vehicle employing electron beam driven inertial confinement fusion engines to reach its target destination. This paper sets out the proposal for a successor interstellar design study called Project Icarus. This is an attempt to redesign the Daedalus vehicle with similar terms of reference. The aim of this study is to evolve an improved engineering design and move us closer to achieving interstellar exploration. Although this paper does not discuss prematurely what design modification are likely to occur some indications are given from the nature of the discussions. This paper is a submission of the Project Icarus Study Group.
Sending robotic probes to solar systems other than our own is a vastly different technical challenge when compared against interplanetary exploration. The nearest stars are over four light years away or a distance of ≈ 272, 000 Astronomical Units (AU). For this reason, history has shown a reluctance to accept the prospects for interstellar travel as realistic. Since 1999 however, astronomical observations of other stars have identified over 400 extra-solar planets, primarily using the radial velocity method [1][2][3]. This has led to the growing possibility that within decades astronomers may identify a habitable world which could, in theory, be one day explored by humans. The technical challenge remains however -even when you know where you want to go how do you get there?
There have been numerous theoretical studies into different propulsion schemes one may use to cross the vast distance of space. A quick review of the various concepts will immediately show that many of those schemes are ruled out. This includes chemical, electric and nuclear fission [4]. This is largely due to either a lack of specific impulse or a lack of thrust to give high exhaust velocity. A high exhaust velocity would be necessary to reach the speeds that are required to travel to another star within the time span of a human lifetime -one of the Terms of Reference of the Icarus mission to be discussed later in this paper. Fuels with comparatively low levels of energy available, for liberation in the form of thrust, would also require a high mass ratio placing constraints on how far the spacecraft can go. [5] Although there are exotic concepts for interstellar travel such as warp drive and wormholes, these are currently considered to be purely speculative [6,7] . Concepts such as antimatter have been investigated but the technology is currently too immature to harness for a spacecraft [8]. Employing the energy from the Sun in solar sail driven vehicles is credible but has the problem that solar intensity reduces inversely with the distance squared. This can be compensated for by using large collimated laser beams [9], but this technology has not been demonstrated for such an application. In the search for fuels which are energetic, provide for low mass ratios, low Thrust/weight ratio for high exhaust velocities, designers are led to consider nuclear pulse engines, in particular with a fusion based fuel.
The idea of using nuclear pulse propulsion was first proposed by Stanislaw Ulam in 1947 and subsequently resulted in an engineering study led by Ted Taylor [10]. This was to employ nuclear pulse technology to propel a vehicle by capturing the blast products of a nuclear explosion on the rear of a giant pusher plate, transferring momentum to the spacecraft and its occupants, cushioned from the blast by several shock absorbers. This eventually led to the Project Orion engineering study with around $11 million being spent over a period of 7 years. The design was for a mission which would take only approx140 years to reach Alpha Centauri with 1 ‘unit of propellant’ being exploded every 3 seconds to push the spacecraft at 1g acceleration to ≈ 3% of light speed [11]. However, with the arrival of various test ban treaties external nuclear pulse was shelved to the archives. Despite this, Project Orion remains the first comprehensive interstellar spacecraft design which was credible.
In 1971 Friedwardt Winterberg explored the concept of using Marx generators to power electron particle beams [12]. This idea was picked up by members of the British Interplanetary Society (BIS) who were considering embarking on an engineering design study to demonstrate that interstellar travel was, at least, possible with current, or near future, technology. Then in January 1973 members of the BIS first met to discuss the challenges of interstellar propulsion and the idea of Project Daedalus was born. Led by Alan Bond, Tony Martin and Bob Parkinson, members came together to create what has become one of the most comprehensive interstellar engineering studies ever undertaken. Project Daedalus had three stated guidelines:
The spacecraft must use current or near future technology.
The spacecraft must reach its destination within a human lifetime.
The spacecraft must be designed to allow for a variety of target stars.
The members of the Daedalus study group were all volunteers but with a solid knowledge of engineering and science. The final design was published in 1978 [13] and was a two-stage spacecraft nearly 200m in length powered by electron driven D/He 3 fusion reactions, eventually accelerating up to 12% of light speed to arrive at its target destination Barnards star 5.9 light years away in under 50 years. The Daedalus first stage had a structural mass of 1, 690 tonnes with 46, 000 tonnes of propellant in six tanks and it would burn for 2.05 years before jettisoning it. The second stage had a structural mass of 980 tonnes with 4,000 tonnes of p
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