Building Blocks for a Generation Ship

Project Hyperion is working on the first ever design of a manned interstellar vessel. Recently, the team thought about how to leverage on existing heritage for the spacecraft’s subsystems. In particular, two major elements of a crewed spacecraft were of particular interest: the propulsion system and the habitat. A preliminary analysis has already been done by the team about two years ago [1].

In a first step, all the options for the propulsion system and the habitat were enumerated. The following criteria were used to select a particular option:

– Level of detail of heritage design

– Applicability to a manned interstellar mission

– Credibility of the heritage design

Options for the propulsion system included Daedalus, Project Icarus’ Ghost Ship, as well as laser sails [2, 3]. For the habitat, various O’Neill colony designs, the Stanford Torus, as well as the 1976 MIT space colony design and the National Space Society’s Kalpana One colony were considered [4-6]. Based on these criteria, the current Project Icarus, Ghost Team’s design was chosen for the propulsion system and the Stanford Torus design for the habitat. The Stanford Torus is the result of a 1975 NASA Summer Study, conducted under participation of such illustrious personalities as Gerard O’Neill and Eric Drexler [5]. The Torus has the capability to sustain the lives of 10,000 to 14,000 inhabitants. This number is in accordance with the recent results obtained by Cameron Smith for the minimum size of a generation ship’s population [7]. However, in order to make the habitat “interstellar-ready”, various modifications are necessary:

– The colony cannot be illuminated by Sunlight and has to be modified to an internal light source

– Radiation shielding has to be modified in order to shield against the increased galactic cosmic rays (GCRs) in interstellar space; extremely energetic particles, which have their origin in violent cosmic events, such as supernovae

– Shielding against interstellar matter has to be provided

– An internal power source is needed, as Sunlight is not available in interstellar space

The Ghost Team’s design has to be modified as well:

– Due to the vastly increased payload (the science payload of the Ghost Ship was 150 tonnes), much more fuel has to be carried on board

– Magsail deceleration is probably not optimal for lower traveling speeds of ~2%c

The team is currently dealing with the following design decisions:

– Radiation shielding options, based on using fusion propellant

– Propulsion system configurations, such as bundling several engines

– Developing a simulation for the mission sequence

– Assess the depth of modifications necessary for the propulsion system and habitat

The Project Hyperion team will present its results of this heritage-based study in the course of 2014. A first result of a high-level analysis can be seen in the image at the top of this article.

 

[1] Hein, A. M., Pak, M., Pütz, D., Bühler, C., & Reiss, P. (2012). World Ships—Architectures & Feasibility RevisitedJournal of the British Interplanetary Society65(4), 119.

[2] Bond, A., & Martin, A. R. (1978). Project Daedalus. Journal of the British Interplanetary Society31, 5.

[3] http://test.icarusinterstellar.org/project-icarus-workshop-update-34-the-ghost-ship/

[4] O’Neill, G. K. (1977). The High Frontier Human Colonies in Space, William Morrow and Company. Inc., New York.

[5] Johnson, Holbrow (1977). “Space Settlements: A Design Study”. National Aeronautics and Space Administration.

[6] Bajoria, A., Arora, N., & Globus, A. (2006). Kalpana One: A New Space Colony Design. In Earth & Space 2006@ sEngineering, Construction, and Operations in Challenging Environment (pp. 1-8). ASCE.

[7] Smith, C. M. (2014). Estimation of a genetically viable population for multigenerational interstellar voyaging: Review and data for project Hyperion.Acta Astronautica97, 16-29.