Frequently Asked Questions
Q: What is Icarus Interstellar?
A: Icarus Interstellar is a nonprofit foundation dedicated to achieving interstellar flight by the year 2100.
Q: Why did you choose fusion based propulsion for Project Icarus?
A: There are several reasons why we selected fusion. Firstly, this project was inspired by Daedalus, whose engine was a pulsed fusion propulsion design. Since Icarus is the successor to Project Dadealus, it made sense to utilize fusion for the bulk of the boost period. Add to this the fact that fusion is arguably a well-understood and mature field of research, and selecting this over less developed areas adds credibility to the design. About a million times more energy is liberated from fusion processes when compared to chemical reactions, and so when we finally learn to harness this energy effectively it will make an ideal energy source for interstellar travel.
Q: Do you anticipate a design quite different from Project Daedalus?
A: We plan to go through successive iterations of the Daedalus design, with the hope of ultimately coming up with a more optimized, and hopefully very different design to the original craft. Based on the progress of the team to date, and the vast leaps in scientific knowledge that we’ve seen since the 1970′s (when Daedalus was designed) we are cautiously optimistic that we will have a unique design solution, very different to Daedalus. It’s hard for us to say at this early stage what the design would physically look like, but it’s possible that we may be looking at a longer, thinner, design, to minimize the spacecrafts cross section, thereby reducing the number of impacts with interstellar dust. At reasonable fractions of the speed of light, even dust can be highly damaging to a space vehicle. We think that multi-staging is also very likely.
Q: What makes an interstellar mission more challenging than interplanetary flight, for example Pioneer or Voyager?
A: There are a multitude of challenges involved in interstellar travel of which propulsion, communications, shielding and autonomy are just a few.
Using current propulsion technology, travel to a nearby star would take close to 100,000 years. To make the trip on timescales of a human lifetime the rocket needs to travel much faster than current probes, at least 5% the speed of light, which is about a thousand times faster than Pioneer. It’s actually physically impossible to do this using chemical rockets, since you’d need more fuel than exists in the known universe. You can figure this remarkable result out quite simply using the Tsiolkovsky rocket equation. Consequently you need to use fuels that are capable of providing profoundly higher thrust efficiency. Fusion is ideal for this, but the propulsion technology is not yet well developed. In addition, fusion processes will typically involve the ejection of very high energy neutrons which need to be ‘thermalized’ (slowed down) to reduce their damaging effects on the spacecraft. Any neutron shield heats up quickly, so in addition to the shielding mass, you also need radiators to radiate the energy away, which also increases the mass of the craft.
The problem of communications over distances of light years is also particularly challenging. Since the signal strength drops off rapidly with increasing distance, you need a very powerful transmitter and potentially a large antenna, and so the Icarus would need to have a lot of power available just to transmit the information that it gathers back to Earth. High data transfer rates are difficult to achieve, so we may only manage a few kilobytes per second.
At such high speeds, collisions with interstellar dust becomes very dangerous, since the dust impacts the spacecraft with a huge amount of kinetic energy equivalent to several kilotons of TNT. For this reason one needs ingenious shielding solutions.
Add the fact that for an unmanned craft whose mission is likely to last decades, one needs a large amount of system autonomy and redundancy. If the craft travels five light years from Earth, for example, it means that any message informing mission control of some kind of system error would take five years to reach the scientists, and another five years for a solution to be received. Ten years is really too long to wait, so the craft needs a highly capable artificial intelligence, so that it can figure out solutions to problems with a high degree of autonomy.
Q: What are some of the technological challenges associated with traveling at significant fractions of the speed of light, 0.1c for example?
A: Traveling that fast implies a very short encounter time at the target solar system. One solution is to decelerate, but that increases the fuel mass required for the mission geometrically. For example, Daedalus was to carry 50,000 tonnes of fuel for its unmanned flyby. If Daedalus were to decelerate in the target system, its initial mass would have needed to be about 2.5 million tonnes. Another problem is the issue of collisions with interstellar dust particles, whose effects can be equivalent to small nuclear explosions on the craft’s skin.
Q: Do you envision some precursor missions before engaging in a full interstellar mission?
A: Absolutely. It makes sense to test the relevant technologies at successively further distances from Earth, for example, a mission to the Oort cloud, or the heliopause. These early precursors would provide critical information that would assist in the evolution of the final interstellar-worthy design.
Q: Why did you choose Alpha Centauri as your target system?
A: No target has yet been selected. We plan to maintain an ‘open door’ policy for as long as possible for Project Icarus, due to the rapid and exciting advances in exoplanet hunting. It is highly unlikely that a target star will be picked that is further than 15 light years from Earth. We favor a much closer star at this stage in the project.
Q: Do you know if there was a scientific case for Project Daedalus choosing Barnard’s star as its destination?
A: At the time of the Daedalus design, it was strongly believed that Barnard’s star contained a planetary system, hence that is why it was chosen as the destination. This was consistent with the scientific evidence of the time, but this has now been disproved.
Q: Can interstellar travel be justified by the scientific return?
A: Any interstellar mission would provide a wealth of scientific knowledge that would keep researchers busy for decades. A probe that was decelerated in some target system containing planets would provide more knowledge still. The scientific justifications for a mission are many-fold.
Q: When Daedalus was proposed, the expansion of humanity in space was widely accepted. How about now?
A: We live in a much more pessimistic time. How can you justify the costs associated an interstellar program? One of the closest asteroids to the Earth has an estimated mineral wealth of around $15 trillion (US). The amount of resources available in our own solar system are gargantuan, and enough to last Earth, and humanity, millennia. We think once we figure out economical ways to access space (Single Stage to Orbit Air-Breathing Rockets come to mind), and to mine the resources, convincing the public will be relatively easy.
Currently only a small fraction of the Earth enjoy wealth and a high standard of living. This prosperity is a direct function of the amount of resources and energy available to a population. We believe that mining the resources within our own solar system will assist in raising the living standards of all. By replacing scarcity with abundance we can reduce the costs of basic resources, and that will allow us to overcome a possible Malthusian catastrophe that awaits us if we don’t choose this path.
However, the big change in the public interest in space is likely to come in a decade or two, when we image the first Earth-like extrasolar planet. Knowing another world, like our Earth, is out there, and being able to actually see it, will generate a profound shift in how we perceive our place in the universe. We believe it will act as a profound catalyst in our desire to explore the universe. Other ‘game-changers’ would be evidence of life (perhaps intelligent) on extrasolar planets.
Q: I want to get involved with this project somehow. Who do I contact?
A: As our nonprofit organization grows, we are always on the lookout for talented and dedicated volunteers to help across a range of areas, including:
- Research and Development
- Popular science writing
- Art, CGI and animation
- Public speaking
- Organization and management
- Business development
- Accounting and administration
- Web development and SEO
If you want to help us in some way, then please email us at firstname.lastname@example.org and start exploring how you can be a part of our endeavor to launch a starship by 2100.