Journey between the stars: The recipe to make Interstellar travel a reality


As scientists from Project Icarus work on ideas to make interstellar travel a reality Paul French asks: how on Earth are they going to do it?

In 1973 the British Interplanetary Society launched Project Daedalus, aiming to establish whether interstellar travel might be possible. Five years later, the project team concluded that it would be feasible, by using current or credible extrapolations of existing technology, to launch an interstellar probe that could reach another solar system on timescales of a normal human lifetime.

Now the society, in collaboration with the US non-profit Icarus Interstellar, is reaching the end of another project, known as Icarus, which has sought to build on the work of Daedalus and bring interstellar travel closer to reality.


Travelling across light years

The main challenge facing the Icarus team is obvious: with the nearest star system, Alpha Centauri, more than four light years away, how can you build something that will get there within the life span of the people involved in the project?

“One of the biggest challenges is creating the energy required,” says Icarus project leader Rob Swinney. “The nearest star is four light years away. If you could travel at the speed of light it would take four years to get there, but to even go at even a fraction of that speed takes a phenomenal amount of energy.

“Chemical rocket powered engines don’t cut it so the Project Icarus team has been looking into designing an unmanned probe that would use fusion technology. That would allow us to go at ten percent of the speed of light, which would mean we could get to the Alpha Centauri in 44 years. Fusion reactors don’t exist yet but the science is well understood and the engineering solution is probably only decades away.”

Project Icarus was launched by the British Interplanetary Society in 2009 in conjunction with the Tau Zero Foundation. For the first couple of years, the conglomeration of over 30 scientists and engineers investigated the problems associated with interstellar travel.

“Since then we’ve been working on creating a credible design for an unmanned craft that can overcome those problems,” explains Swinney. “At the moment we have four different possible designs and two possible engine types. We’re currently trying to narrow it down to one design.”

“One of the biggest challenges is creating the energy required”

The need for speed

Back in the 1970s the Project Daedalus team identified inertial confined fusion (ICF) as the best way of propelling their probe quickly enough to negate the issues of time and distance to the nearest star. The Icarus team has sought to build on and refine this approach.

“The Daedalus ICF design basically involves using an electron beam to hit a pellet of fuel and a magnetic field to draw it out of the exhaust,” Swinney explains. “The Daedalus team discarded lasers because the technology wasn’t that advanced then, but it has come on in leaps and bounds since. That’s why we’ve decided to base our designs around laser ignition. So you’d put fuel pellets into the reaction chamber, hit them with a laser and use superconductors to create a strong magnetic field to force the plasma out of the exhaust. Some of the energy is then captured to ‘bootstrap’ the next cycle.”

The other potential engine design the researchers are looking into uses a Z-pinch concept. Swinney explains: When a lightning rod on a building is hit by a lightning strike and a large current is discharged, you’d expect it to be smashed. However, the huge current creates a magnetic field around the rod that creates an inward force so strong it actually crushes the rod. We’re looking into whether we could use that force to squeeze a plasma stream enough to fuse the fuel rather than the pellets and laser.”

Payload problems

On a project as complex as Icarus it is almost inevitable that as one door opens, another closes. Managing to solve the issue of creating enough energy to send the probe interstellar at a reasonable speed creates a range of other headaches.

“Another major problem is the mass of the probe,” says Swinney. “The Daedalus probe had an all up mass of over 54,000 tonnes with a payload of 450 tonnes and we want to make Icarus smaller but if anything it is likely to be bigger with a smaller payload.

“A reason for this is that Daedalus was a fly-through probe. Our intention is to decelerate Icarus into orbit around the target star, which requires even more fuel and adds even more mass onto the probe.”


Handling the heat

For engines to work effectively they must create an enormous amount of heat. This is a hard enough problem to solve for conventional spacecraft, says Swinney, let alone one creating enough energy to fly interstellar missions.

“Heat is hard to get rid of in the vacuum of space but you need to do it if you don’t want to fry your equipment,” he explains. “Most spacecraft currently use radiators to radiate energy into space but that would be harder for us if we’re using fusion reactors because they’ll generate even more heat. Adding in more radiators to deal with this could add significant weight to the probe.

“One theory we’re exploring to overcome this is to use liquid droplet radiation. Essentially we’d pump liquid drops into space, collect them once they’ve cooled and re-use them as part of the cooling process.”

“Heat is hard to get rid of in the vacuum of space”

Shields up

There are lots of tiny dust particles far out in space. As high-speed collisions could potentially prove fatal, shielding is an important aspect of any interstellar probe design.

“If you were to hit dust particles whilst travelling at ten percent of the speed of light, they could easily destroy your machine,” says Swinney. “Project Daedalus looked into the idea of firing particles out the front of the probe that could vaporise the dust. However, they also designed a shield to go on the front of their probe and we concluded that it would be enough to protect it, so will incorporate that into our design.”

Navigating deep space

Navigation is surprisingly simple for solar system missions. NASA has a deep space network that allows spacecraft to know how far from Earth they are, and also uses star sensors for attitude control. However, all that will go out the widow once you exit the solar system.

“Navigation will be different,” says Swinney. “The nearest star is beyond the deep space network and it will be harder to navigate because the local stars that appeared fixed before will move. However, with some clever algorithms we think we’ll be able to take this into account and build a system that can find its way around.”


Signal lost

If you’ve ever complained about a mobile phone signal in a remote part of the world, spare a thought for a probe designed to go interstellar. At four lights years from Earth, how do you hope to beam a signal back?

“Transmission rates get slower and slower for probes in the outer solar system,” says Swinney. “The problem for us is once you get out to the nearest star, how do you transmit back to Earth?”One idea we’re looking at is gravitational lensing. Basically, you can use a heavy object to bend light and see things further away.

“The sun has its own gravitational lensing point. We think we may be able to use it to magnify a transmitter and boost it back to the deep space network. That could be one of the first precursor missions – to send a probe out to the sun’s gravitational bending point and see if it works.”

“Transmission rates get slower and slower for probes in the outer solar system”

Looking to the future

Project Icarus has inspired further study into interstellar travel. Icarus Interstellar is a non-profit organisation launched in the US to help manage Project Icarus and other related projects and in 2012, the US Defense Advanced Research Projects Agency funded the 100 Year Star Ship project with the intention of making the capability for human interstellar flight a reality within 100 years.

“There’s now a community across the world looking into this,” says Swinney. “I suspect that there will be half a dozen or so problems that will drop out of Icarus. We’d then hope to influence people with money like the national agencies into investing in some precursor missions that could help to solve those problems.”

Fusion technology is decades away, but sending a probe could happen sooner than we think. The Japanese Space Agency, for instance, is currently flying a probe around the solar system using solar sails, which are covered in reflective material and use the sun’s light for propulsion.

“The problem with fusion is the amount of fuel,” Swinney explains. “Solar sails could take away that problem but the force they produce is tiny so another thing we’re looking into is the possibility of a beam-driven sail. It might be possible for small payloads and that technology is much closer than fusion. If you could combine it with a nuclear-electric engine it might be possible to send a probe within the next ten years.”

So, will people one day be able to travel between the stars? “Personally, I think they will,” Swiney says. “We’re not that far away from living and working in the solar system. I think from there we’ll progress further out. We underestimate how much we can achieve. Just over a hundred years ago we were building planes out of old bicycle parts but 60 years later we put a man on the moon.”

Images courtesy of Icarus Interstellar by Nick Stevens/Robert van der Veeke/Adrian Mann

Asteroids: The Next Frontier of Mining?


More than 1,500 asteroids are in near reach of the Earth and are packed full of valuable resources from water to platinum.

If we were able to access them, they might help us top up declining supplies on Earth. Charlotte Richardson Andrews asks asteroid explorers how far their projects have progressed

“I think we are living in the most exciting time period in the history of our species”, says Chris Lewicki, president and chief engineer of Seattle-based Planetary Resources. “We have the opportunity to become a multi-planetary species and that’s exciting.”


The private, commercial company is at the forefront of the burgeoning asteroid mining industry, which seeks to mine near-earth asteroids (NEAs) for precious metals and other valuable materials. Planetary Resources enjoy the backing of Hollywood director James Cameron and Google executives Larry Page and Eric Schmidt and has made leaps since its launch in 2010.

The company currently operates as a team of 40, with a number of NASA scientists and engineers among their ranks. “Small teams are now able to do what it used to take whole governments to do,” says Lewicki.

“One engineer who’s coming out of an undergraduate university program with a desktop computer and a set of commercially available tools really has as much design capability and computing power as an entire department at NASA had in the 1960s.”


Getting into space

The team is currently busy at work at Planetary Resources’ new facilities, building prospecting spacecraft. Developing and producing its own technology in-house is both economic and savvy for a moderately small company with big aims, says Lewicki. “This is a way for us to make quick progress, to keep up with new tech trends as they emerge and also to dramatically reduce the cost of exploring deep space.”

The company’s current project is the partially crowd-funded Arkyrd, which will be launched this autumn from the International Space Station.

“It’ll be our first satellite,” explains Lewicki. “It’ll demonstrate a lot of the core technologies that we intend to use in the commercial exploration of asteroids. We’ve done a lot of stuff here on earth, but getting into space still has a long queue; we’re coming to the front of that line.”


Readying its engines at the front of this line is NASA. In less than two years’ time, the agency will launch its Origins, Spectral Interpretation, Resource Identification, Security and Regolith Explorer (OSIRIS-REx) mission. If successful, OSIRIS-REx will be the first US mission to carry samples gathered from an asteroid back to Earth.

It’s something Planetary Resources hopes to have achieved in the next decade, says Lewicki, adding: “We’re familiar with the mission, and many of the team members. The Japanese are also launching a mission, the Hayabusa 2, to an asteroid later this year. The data these missions gather will be very useful for commercial exploration.”

“The company’s current project will be launched this autumn from the ISS”

Growing interest in commercial exploration of NEAs has prompted studies into how financially lucrative asteroid mining might be for companies such as Planetary Resources and the newer Deep Space Industries, which appeared in 2013.

A recent study by Harvard astrophysicist Dr Martin Elvis suggests that just ten NEAs might be suitable for commercial-scale mining – a potentially disappointing summary. But Lewicki, who is in regular contact with Dr. Elvis, says the assessment’s conclusion is essentially a very conservative, worst-case scenario.

“Martin was looking at the metallic asteroids in particular, which make up just a few percent of the solar system’s asteroids,” he points out. “Our interest is in the carbonaceous ones, which make up almost 20% of the solar system, so we’re much more optimistic about things.”

The target of the OSIRIS-Rex mission, asteroid Bennu, is one such carbonaceous asteroid. NASA’s spacecraft will launch in September 2016 and arrive at Bennu in October 2018 to study the asteroid and collect samples before returning to earth in 2023.


While Planetary Resources is interested in mining for profit, the motives behind NASA’s OSIRIS-Rex mission are primarily scientific. Since asteroids are relics from our solar system’s formation, NASA believes analysis of the samples will give the scientific community – and the wider world – invaluable insights into how the planets formed and how life as we know it originated.

The agency also believes its spacecraft will be able to accurately measure how the tiny push from sunlight alters the orbit of Bennu, helping astronomers to better predict this influence on the path of any asteroid that might present the risk of impacting Earth.

“NASA’s spacecraft will arrive at Bennu in October 2018 to study the asteroid”

Leaps in technology

Asteroid exploration technology is developing at a rapid pace, says Lewicki, including telescopes that allow us to identify what type of materials an asteroid may contain without ever leaving Earth.

Brighter, stony S-type asteroids contain a significant amount of metal – mostly iron, nickel and cobalt. They also contain a fair amount of trace elements such as gold, platinum and rhodium. Metallic M-class asteroids are rare and contain about ten times more metal than C-type asteroids, which are dark, carbon-rich and abundant in water sources.

Planetary Resources is primarily interested in C-types, says Lewicki. “C-types are maybe the oldest, most primitive types in the solar system. They can contain hydrogen, oxygen, nitrogen and even carbon. Those four elements are the building blocks of a number of things like water, methane and ammonia,” he explains.

“We can even take the hydrogen and oxygen and combine them to create rocket fuel. As a material that costs $50m for every ton sent into space, it’s extremely valuable if we can get it in space instead of having to transport it from earth, which continues to be a very expensive thing to do.”


While Earth-orbit telescopes can provide useful data, the OSIRIS-REx spacecraft is equipped with instruments that map an asteroid’s composition from a much closer vantage point, allowing the team to accurately identify and select the best sample sites.

These instruments include three spectrometers that determine an asteroid’s composition by analysing the light they reflect, emit and absorb, in ranges that the human eye is incapable of detecting, such as X-ray and infrared.

Increasingly sophisticated technology has seen our knowledge of asteroids grow exponentially in the last 15 years, points out. “Over 90% of the asteroids current being tracked have been discovered since the year 2000, and 2,000 more have been discovered since we announced the company,” says Lewicki. “There has even been confirmation of hydrogen, or hydroxyls, on asteroids in the main belt – specifically asteroid 24 Themis.”

Other advances made in recent years include the mapping of certain asteroids and even a better understanding of the science behind how asteroids are held together. “It really is an area where there has been a tremendous amount of progress is being made,” says Lewicki.

“Over 90% of the asteroids current being tracked have been discovered since the year 2000”

Regulators need to catch up

This progress has prompted the US Government to begin drafting HR 5063, otherwise known as the American Space Technology for Exploring Resource Opportunities In Deep Space (ASTEROIDS) Act. The legislation aims to promote private exploration, protect commercial rights over mined materials and regulate this burgeoning, potentially lucrative industry.

While the ethics of asteroid mining may be debatable – with critics claiming more effective on-Earth recycling systems could negate the need to mine for supposedly unsustainable resources ¬– the bill will comply with international obligations set out in the 1967 Outer Space Treaty, which bans states from making a claim to ownership of any celestial body.

With companies such as Planetary Resources and Deep Space industries vying for these resources, how will the act legislate in regards to commercial competition? “This is something that will be debated as the act itself is discussed in congress,” says Lewicki. “The regulatory environment is something that is yet to be created and defined.”

Legislation may have to be rapid to match the ever-advancing field of NEA exploration.

“The Outer Space Treaty bans states from making a claim to ownership of any celestial body”

Human vs robotic asteroid miners

While NASA has been focusing its attention on the human exploration of asteroids, Planetary Resources is more invested in the robotic, remotely controlled breed of space age explorer.

“We’re used to having humans involved in opening up these frontiers, but technology has gotten to a point where we can teleoperate [robotic miners].” Lewicki cites self-driving vehicles, autonomous drones and the rovers that have been traversing Mars’ surface for the past 20 years as positive examples of this.

“We’re making advances in this area of science all the time, and we’re now in a position where we can undertake asteroid mining robotically,” he adds.

“Technology has gotten to a point where we can teleoperate robotic miners”

“It means we don’t have human lives on the line, and it drastically reduces the need for the multi-billion dollar budgets required to support human exploration.”

While NASA has a tax-funded pot to draw on, Planetary Resources is a smaller operation, relying on the support of affluent, high profile backers.

But the fact that the company raised $1.5m for the Arkyd via Kickstarter last year – promising backers access to the Arkyd that will allow them to photograph asteroids, stars and even project selfies from orbit – shows that it can also draw on support from a public who understand that asteroid mining is no longer confined to science fiction.

People shouldn’t ask ‘if’ when it comes to asteroid mining anymore, says Lewicki, but rather ‘when’.

Images courtesy of Nasa