Editing Project Daedalus (section)

==Concept==
Daedalus would be constructed in Earth orbit and have an initial mass of 54,000 [[tonnes]] including 50,000 tonnes of fuel and 500 tonnes of scientific payload. Daedalus was to be a two-stage spacecraft. The first stage would operate for two years, taking the spacecraft to 7.1% of [[light speed]] (0.071 ''c''), and then after it was jettisoned, the second stage would fire for 1.8 years, taking the spacecraft up to about 12% of light speed (0.12 ''c''), before being shut down for a 46-year cruise period. Due to the extreme temperature range of operation required, from near [[absolute zero]] to 1600 K, the [[Bell nozzle|engine bells]] and support structure would be made of [[molybdenum]] alloyed with [[titanium]], [[zirconium]], and [[carbon]], which retains strength even at [[cryogenic temperature]]s. A major stimulus for the project was [[Friedwardt Winterberg]]'s [[inertial confinement fusion]] drive concept,<ref name="study"/><ref>F. Winterberg, "Rocket propulsion by thermonuclear microbombs ignited with intense relativistic electron beams", Raumfahrtforschung 15, 208-217 (1971).</ref> for which he received the Hermann Oberth gold medal award.<ref>Winterberg is [[Hermann Oberth]] Gold Medalist, [https://dx.doi.org/10.1063/1.2995324 Physics Today, December 1979]</ref>

This velocity is well beyond the capabilities of [[chemical rocket]]s or even the type of [[nuclear pulse propulsion]] studied during [[Project Orion (nuclear propulsion)|Project Orion]]. According to Dr. [[Donald A. Martin|Tony Martin]], controlled-fusion engines and the [[Nuclear electric rocket|nuclear–electric systems]] have very low [[thrust]] because equipment to convert nuclear energy into electrical has a large mass which results in small [[acceleration]], taking a century to achieve the desired speed; thermodynamic nuclear engines of the [[NERVA]] type require a great quantity of fuel. [[Photon rocket]]s have to generate power at a rate of 3{{e|9}} W per kg of vehicle mass and require mirrors with [[Absorptance|absorptivity]] of less than 1 part in 10<sup>6</sup>. [[Interstellar ramjet]]'s problems are the tenuous interstellar medium with a density of about 1 atom/cm<sup>3</sup>, a large diameter funnel, and high power required for its electric field. Thus the only suitable propulsion method for the project was [[Nuclear pulse propulsion|thermonuclear pulse propulsion]].<ref>{{Cite web|url=http://daedalus-zvezdolet.narod.ru/doceng/07eng.doc|archiveurl=https://web.archive.org/web/20130628001133/http://daedalus-zvezdolet.narod.ru/doceng/07eng.doc|url-status=dead|title=Project Daedalus: The Propulsion System Part 1; Theoretical considerations and calculations. 2. Review of Advanced Propulsion Systems|archivedate=June 28, 2013}}</ref><ref>{{Cite journal|url=https://ui.adsabs.harvard.edu/abs/1978JBIS...31S...5B/abstract|title=Project Daedalus|first1=A.|last1=Bond|first2=A. R.|last2=Martin|date=January 1, 1978|journal=Journal of the British Interplanetary Society Supplement|volume=31|pages=S5–S7|bibcode=1978JBIS...31S...5B |via=NASA ADS}}</ref><ref>{{Cite web|url=http://geocities.com/televisioncity/2049/DAEDALUS.HTM|url-status=dead|archive-url=https://web.archive.org/web/20091026192110/http://geocities.com/televisioncity/2049/DAEDALUS.HTM|title=Project Daedalus – Origins|archive-date=26 October 2009|via=GeoCities}}</ref>

Daedalus would be propelled by a [[fusion rocket]] using pellets of a [[deuterium]]/[[helium-3]] mix that would be ignited in the reaction chamber by [[inertial confinement fusion|inertial confinement]] using [[electron beam]]s. The electron beam system would be powered by a set of [[induction coils]] trapping energy from the [[plasma (physics)|plasma]] exhaust stream. 250 pellets would be detonated per second, and the resulting plasma would be directed by a [[magnetic nozzle]]. The computed burn-up fraction for the fusion fuels was 0.175 and 0.133 producing exhaust velocities of 10,600&nbsp;km/s and 9,210&nbsp;km/s respectively. Due to scarcity of helium-3 on Earth, it was to be mined from the atmosphere of [[Jupiter]] by large [[hot-air balloon]] supported robotic factories over a 20-year period, or from a less distant source, such as the [[Moon]].<ref>[[Helium-3#Extraterrestrial abundance]]</ref>

The second stage would have two 5-metre [[optical telescope]]s and two 20-metre [[radio telescope]]s. About 25 years after launch these telescopes would begin examining the area around Barnard's Star to learn more about any accompanying planets. This information would be sent back to Earth, using the 40-metre diameter second stage [[Bell nozzle|engine bell]] as a communications dish, and targets of interest would be selected. Since the spacecraft would not decelerate, upon reaching Barnard's Star, Daedalus would carry 18 autonomous sub-probes that would be launched between 7.2 and 1.8 years before the main craft entered the target system. These sub-probes would be propelled by [[Nuclear electric rocket|nuclear-powered]] [[ion drive]]s and would carry cameras, [[spectrometer]]s, and other sensory equipment. The sub-probes would fly past their targets, still travelling at 12% of the speed of light, and transmit their findings back to the Daedalus' second stage, mothership, for relay back to Earth.

The ship's payload bay containing its sub-probes, telescopes, and other equipment would be protected from the [[interstellar medium]] during transit by a [[beryllium]] disc, up to 7&nbsp;mm thick, weighing up to 50 tonnes.  This erosion shield would be made from beryllium due to its lightness and high latent heat of vaporisation. Larger obstacles that might be encountered while passing through the target system would be dispersed by an artificially generated cloud of particles, ejected by support vehicles called dust bugs about 200&nbsp;km ahead of the vehicle. The spacecraft would carry a number of [[robot]] wardens capable of autonomously repairing damage or malfunctions.