Pegasus Interstellar Probe
In 2009 I initiated Project Icarus, an effort to design an interstellar rendezvous probe as an exercise in the application of extreme aerospace engineering. Over the years this has led to dozens of peer reviewed publications by members of the team. Recently we have began the process of bringing the project to a final close. We held our close-out symposium in September 2023 and we are now busy finishing up the final papers.
My own work, has focussed on a particular design called Pegasus, which is a four-engine parallel thrust system carrying a 150 tons science payload to orbit around one of the exoplanets of Centauri A/B. Travelling at a cruise velocity of 0.046c or 13,680 km/s it reaches the destination target in a trip time of just under 100 years.
Orthographic Depiction of the Pegasus Interstellar Spacecraft Concept Design
Designing fusion engines is difficult and as a team we have spent many hours thinking about the problem, on a project that has endured for 15 years. Although this is a purely theoretical exercise, we have been using our engineering and physics skills to produce concepts for machines that may one day become feasible. This has required a combination of existing technology integrated into near-future technology, through a process of extrapolation from current technology trends.
The Pegasus, uses an inertial confinement fusion engine driven by high energy laser beams. The fuel capsules are pretty big at 72 milli-grams and they are detonated at a frequency of 1,000 Hz. This produces a mass flow rate of 0.288 kg/s, thrust of 2.65 MN, jet power 12.21 TW and a specific power of 2.45 MW/kg. As I said, designing fusion engines for deep space exploration is hard and challenging.
Four Parallel Thrust Engines of the Pegasus Interstellar Spacecraft
The laser requirements for the propulsion system is 145 MJ operating with an efficiency of 36% and a peak power of 903,427 TW, with 50 separate beamlines firing down onto the target. Yet this is for an assumed energy gain of 23, which is not great but perhaps what might be expected from a commercial ground reactor that supplies energy to a national electrical grid. However, for this study I have assumed worst case conditions and I could have assumed much higher energy gains in order to get the total mass down. For example a Mars study called Vista previously assumed an energy gain of 1500. But I would just rather start from the bottom line definition and then allow others to improve on the model.
I have also been costing the probe, which includes the design and development phase, construction and production phase and the mission utilisation phase. Currently its coming in at around $150 Billion. The biggest factor in the Capital Expenditure Model (Capex) is the acquisition costs of obtaining helium-3 such as from gas giant mining, since the Pegasus requires 43,300 tons of Deuterium-Helium-3 fuel in equimolar mixture. I have also costed a program to lead up to the launch of Pegasus, to include lower energy flights into the Solar System with increasing reach and velocity. The total program is currently coming it at around $300 Billion, over a timespan of around 150 years. That is $2 Billion per year or $20 Billion per decade - smaller than the current NASA budget.
Pegasus Scientific Payload with Autonomous Artificial Intelligence Capability
The payload would be controlled by an artificial intelligence computer, and it would also carry an on-board self-repair factory and spare parts using large robotic arms similar to what is currently on the ISS. Once it arrived at the local planetary system it would deploy dozens of smaller spacecraft to include orbiters, atmospheric penetrators, surface landers and rovers, to permit a full scientific reconnaissance of the planetary system and all celestial objects. All of the papers for the project should be submitted to the Journal of the British Interplanetary Society during October/November 2024 so look out for their release in 2025. The key papers pertaining to Pegasus includes:
Project Icarus: The Pegasus Spacecraft Concept Design ICF Propulsion for an Interstellar Rendezvous Mission.
Project Icarus: The Pegasus Spacecraft Concept Design Engineering Systems Description.
Project Icarus: Strategic Roadmap Conclusions of the Starship Design Study.
Think of all the benefits that would come from the development of such a spacecraft. If humanity was to pull its resources and work towards such a visionary goal as interstellar spaceflight. How constructive would be the application of our energies and how creative would be the utilisation of our intellectual capacity as a species in search of knowledge.
The Pegasus is more than just an engineering machine. It represents hope itself. Hope that humanity can grow wings and become something greater than the quagmire of despair it has currently become as conflicts rage around the world. Think of all the jobs it would create. Consider all of the new technology spin-offs that would result from the construction of such a machine. How transformative those technologies could be on the human condition. The visionary inspiration that it would cause. The enhancement of our educational standards as young people found careers that would enable them to contribute to such an exciting initiative.
A Single Engine for the Pegasus Interstellar Spacecraft Concept Design
It is initiatives like this which I think is the solution to humanity’s problems. Nations need to find ways of co-operating together on large scale endeavours that can bring massive benefit to the contemporaneous society but also help to secure a prosperous future. This doesn’t just apply to space, but to exploration of the oceans, or inside the Earth, or the microbes under a microscope, or finding cures for diseases. Big project problems being attacked by the world’s best scientists working in co-operation as a common humanity.
History has often depicted a great hero on a horse coming to save a people. In England this is King Arthur, a leader in post-Roman Britain in battles against the Anglo-Saxons during the 5th and 6th centuries. There is also Queen Boudica of the ancient Iceni tribe who led an uprising against the conquering forces of the Roman empire around AD 60. A large statue of her stands on the banks of the River Thames in London today so British people never forget the value of their freedom and the boot of oppression and tyranny.
Pegasus had a rider too, his name was Bellerophon from ancient Greek mythology. He was the slayer of monsters and he killed the Chimera in the Illiad, the epic written by Homer about the battle of Troy. It was Bellerophon that captured and tamed the winged horse Pegasus. That is a metaphor for us in the current times, that in order to become a great civilization among the stars we must capture and tame the starship Pegasus. We must learn how to design it, and then to one day build it. This takes great perseverance, many years of effort and a degree of co-operation currently lacking from our world. I continue to hope that one day humanity will grow up and finally learn to take flight among the stars. For then we will be creating our own mythology as we embark on epic journeys in the Cosmos and beyond.
Pegasus Parallel Thrust Engines Lighting up under Acceleration
Pegasus arrives at Some Distant Exoplanets in Search of the Unknown
