Star Ark: A Living, Self-Sustaining Spaceship

Think of the ease. With a simple command of “Make it so” humans travelled from one star to the next in less time than for drinking a cup of coffee. At least that’s what happens in the time-restricted domain of television. In reality it’s not so easy. Nor does Rachel Armstrong misrepresent this point in her book of essays within “Star Ark – A Living Self-Sustaining Spaceship“; a book that brings some fundamental reality to star travel.

Yes, many people want to travel to other stars. We’re not ready for that. We’re still just planning on getting outside Earth’s protective atmosphere (again). Yet making preparations and doing judicious planning is the aim of this book. Wisely though, this book isn’t technical. It has no mention of specific impulse calculations or ion shields. Rather, this book takes a very liberal view of space travel and ponders deep questions such as whether the cosmos is an ecosystem.

Does our species have an appropriate culture for space travel? What exactly is a human? These concerns get raised in some very thought provoking sections. And given that the editor is an architect and one who apparently considers the emotional qualities of a structure as much as functional qualities, then this book’s presentation tends to be a little more on the philosophical side of things.

In particular, it looks at the benefits of living entities. For instance it notes that humans live in symbiotic relationships with a host of internal and external organisms. Most have already gone into space either within people who have traveled in space or possibly upon probes sent to other planets. So we aren’t the only species that’s traveled beyond Earth. But which beings are sufficient and necessary to keep humans alive for the generations needed to travel to another star? That question and many answers come up often.

As well, the essays get into bigger questions such as: What is life? Could the vessel be an organic construct? How might today’s humans evolve to tomorrow’s star travelers? Should humans travel in space and promote/continue panspermia? Yes, these questions and many more are raised in the essays collected within this book. And true to form for any book considering star travel, there aren’t any strict answers. There are however lots of ideas and concepts to better prepare humans.

Much of this book seems to center around the authors’ involvement with the Persephone project of Icarus Interstellar. Yet there’s very little description of either. However, the book does have wonderful descriptions of Biitschli experiments, explanations of living walls and critiques of theatrical productions.

There are a few fictional passages and some poetry. The long list of references indicates a broad knowledge of the technical issues, though the focus is on humanity and the living aspect. This focus flows through the essays, but having a collection of many authors makes for a disjointed flow. The writing styles are unique, the viewpoints are particular and the emphasis specialized for each. One common viewpoint does keep arising though. That is, we are already on a living spaceship; the Earth. Earth gives a unique platform for assessing the ability to travel to other stars. The essays state that it is or at least was a veritable, closed self-sustaining life support system. And, as seems to be the norm these days, the essays acknowledge that solutions for space travel would be just as good for people remaining behind upon Earth or travelling to the Moon or to Mars and so on. This care and concern for living organism keeps the book grounded, so to speak.

The all-encompassing-solution-finder may be a strength or a weakness to Rachel Armstrong’s collection within the book “Star Ark – A Living Self-Sustaining Spaceship”. As the book’s essays describe, humans have an incredible ability to think and act in abstract fashion. Just envisioning an attempt to send sentient beings to another star demonstrates this. But will we be able to enact this idea and what form might a star vessel take? Reading of this is easy. Will taking the necessary steps be just as easy?

The book is available here through Springer.
Learn more about the author, Rachel Armstrong, here.

Breakthrough Lofts the Smallest Satellites Ever, not Interstellar Yet, but a Step Forward

In 2015, Russian billionaire Yuri Milner established Breakthrough Initiatives, a non-profit organization dedicated to enhancing the search for extraterrestrial intelligence (SETI). In April of the following year, he and the organization be founded announced the creation of Breakthrough Starshot, a program to create a lightsail-driven “wafercraft” that would make the journey to the nearest star system – Alpha Centauri – within our lifetime.

This past June, the organization took a major step towards achieving this goal. After hitching a ride on some satellites being deployed to Low Earth Orbit (LEO), Breakthrough conducted a successful test flight of its first spacecraft. Known as “Sprites”, these are not only the smallest spacecraft ever launched, but prototypes for the eventual wafercraft Starshot hopes to send to Alpha Centauri.

The concept for a wafercraft is simple. By leveraging recent developments in computing and miniaturization, spacecraft that are the size of a credit card could be created. These would be capable of carrying all the necessary sensors, microprocessors and microthrusters, but would be so small and light that it would take much less energy to accelerate them to relativistic speeds – in the case of Starshot, up to 20% the speed of light.

Artist’s illustration of a light-sail powered by a laser beam (red) generated on Earth’s surface. Credit: M. Weiss/CfA

As Pete Worden – Breakthrough Starshot’s executive director and the former director of NASA’s Ames Research Center – said in an interview with Scientific American:

“This is a very early version of what we would send to interstellar distances. In addition, this is another clear demonstration that it is possible for countries to work together to do great things in space. These are European spacecraft with U.S. nanosatellite payloads launching on an Indian booster—you can’t get much more international than that.”

Professor Abraham Loeb also has some choice words to mark this historic occasion. In addition to being the Frank B. Baird Jr. Professor of Science, the Chair of the Astronomy Department and the Director of the Institute for Theory and Computation at Harvard University, Prof. Loeb is also the chairman of the Breakthrough Starshot Advisory Committee. As he told Universe Today via email:

“The launch of the Sprite satellites marks the first demonstration that miniaturized electronics on small chips can be launched without damage, survive the harsh environment of space and communicate successfully with earth. The Starshot Initiative aims to launch similar chips attached to a lightweight sail that it being pushed by a laser beam to a fifth of the speed of light, so that its camera, communication and navigation devices (whose total weight is of order a gram) will reach the nearest planet outside the solar System within our generation.”

A prototype Sprite nanosatellite, showing its solar panel, microprocessors, sensors and transmitters. Credit: Zac Manchester

The craft were deployed on June 23rd, piggybacking on two satellites belonging to the multinational technology corporation OHB System AG. Much like the StarChips that Starshot is proposing, the Sprites represent a major step in the evolution of miniature spacecraft that can do the job of larger robotic explorers. They measure just 3.5 by 3.5 cm (1.378 x 1.378 inches) and weight only four grams (0.14 ounces), but still manage to pack solar panels, computers, sensors and radios into their tiny frames.

The Sprite were originally conceived by Zac Manchester, a postdoctorate researcher and aerospace engineer at Cornell University. Back in 2011, he launched a Kickstarter campaign (called “KickSat“) to raise funds to develop the concept, which was his way of bringing down the associated costs of spaceflight. The campaign was a huge success, with Manchester raising a total of $74,586 of his original goal of $30,000.

Now a member of Breakthrough Starshot (where he is in charge of Wafer design and optimization), Manchester oversaw the construction of the Sprites from the Sibley School of Mechanical and Aerospace Engineering at Cornell. As Professor Loeb explained:

“The Sprites project is led by Zac Manchester, a Harvard postdoc who started working on this during his PhD at Cornell. Sprites are chip-size satellites powered by sunlight, intended to be released in space to demonstrate a new technology of lightweight (gram-scale) spacecrafts that can communicated with Earth.”
Zac Manchester holding a prototype KickSat. Credit: Zac Manchester/kickstarer

The purpose of this mission was to test how well the Sprites’ electronics systems and radio communications performed in orbit. Upon deployment, the Sprites remained attached to these satellites (known as “Max Valier” and “Venta”) and began transmitting. Communications were then received from ground stations, which demonstrated that the Sprites’ novel radio communication architecture performed exactly as it was designed to.

With this test complete, Starshot now has confirmation that a waferocraft is capable of operating in space and communicating with ground-based controllers. In the coming months and years, the many scientists and engineers that are behind this program will no doubt seek to test other essential systems (such as the craft’s microthrusters and imagers) while also working on the various engineering concerns that an instellar mission would entail.

In the meantime, the Sprites are still transmitting and are in radio contact with ground stations located in California and New York (as well as radio enthusiasts around the world). For those looking to listen in on their communications, Prof. Loeb was kind enough to let us know what frequency they are transmitting on.

The radio frequency at which the Sprites that were just launched operate is 437.24 MHz, corresponding to a wavelength of roughly 69 cm,” he said. So if you’ve got a ham radio and feel like tuning in, this is where to set your dials!

And be sure to check out Zac Manchester’s Kickstarter video, which showcases the technology and inspiration for the KickSat:

Further: Breakthrough Initiatives

Could Space Travelers Melt As They Accelerate Through Deep Space?

Forty years ago, Canadian physicist Bill Unruh made a surprising prediction regarding quantum field theory. Known as the Unruh effect, his theory predicted that an accelerating observer would be bathed in blackbody radiation, whereas an inertial observer would be exposed to none. What better way to mark the 40th anniversary of this theory than to consider how it could affect human beings attempting relativistic space travel?

Such was the intent behind a new study by a team of researchers from Sao Paulo, Brazil. In essence, they consider how the Unruh effect could be confirmed using a simple experiment that relies on existing technology. Not only would this experiment prove once and for all if the Unruh effect is real, it could also help us plan for the day when interstellar travel becomes a reality.

To put it in layman’s terms, Einstein’s Theory of Relativity states that time and space are dependent upon the inertial reference frame of the observer. Consistent with this is the theory that if an observer is traveling at a constant speed through empty vacuum, they will find that the temperature of said vacuum is absolute zero. But if they were to begin to accelerate, the temperature of the empty space would become hotter.

According to the theory of the Unruh effect, accelerating particles are subject to increased radiation. Credit: NASA/Sonoma State University/Aurore Simonnet

This is what William Unruh – a theorist from the University of British Columbia (UBC), Vancouver – asserted in 1976. According to his theory, an observer accelerating through space would be subject to a “thermal bath” – i.e. photons and other particles – which would intensify the more they accelerated. Unfortunately, no one has ever been able to measure this effect, since no spacecraft exists that can achieve the kind of speeds necessary.

For the sake of their study – which was recently published in the journal Physical Review Letters under the title “Virtual observation of the Unruh effect” – the research team proposed a simple experiment to test for the Unruh effect. Led by Gabriel Cozzella of the Institute of Theoretical Physics (IFT) at Sao Paulo State University, they claim that this experiment would settle the issue by measuring an already-understood electromagnetic phenomenon.

Essentially, they argue that it would be possible to detect the Unruh effect by measuring what is known as Larmor radiation. This refers to the electromagnetic energy that is radiated away from charged particles (such as electrons, protons or ions) when they accelerate. As they state in their study:

“A more promising strategy consists of seeking for fingerprints of the Unruh effect in the radiation emitted by accelerated charges. Accelerated charges should back react due to radiation emission, quivering accordingly. Such a quivering would be naturally interpreted by Rindler observers as a consequence of the charge interaction with the photons of the Unruh thermal bath.”

Diagram of the experiment to test the Unruh effect, where electrons are injected into a magnetic field and subjected to lateral and vertical pulls. Credit: Cozzella, Gabriel (et al.)

As they describe in their paper, this would consist of monitoring the light emitted by electrons within two separate reference frames. In the first, known as the “accelerating frame”, electrons are fired laterally across a magnetic field, which would cause the electrons to move in a circular pattern. In the second, the “laboratory frame”, a vertical field is applied to accelerate the electrons upwards, causing them to follow a corkscrew-like path.

In the accelerating frame, Cozzella and his colleagues assume that the electrons would encounter the “fog of photons”, where they both radiate and emit them. In the laboratory frame, the electrons would heat up once vertical acceleration was applied, causing them to show an excess of long-wavelength photons. However, this would be dependent on the “fog” existing in the accelerated frame to begin with.

In short, this experiment offers a simple test which could determine whether or not the Unruh effect exists, which is something that has been in dispute ever since it was proposed. One of the beauties of the proposed experiment is that it could be conducted using particle accelerators and electromagnets that are currently available.

On the other side of the debate are those who claim that the Unruh effect is due to a mathematical error made by Unruh and his colleagues. For those individuals, this experiment is useful because it would effectively debunk this theory. Regardless, Cozzella and his team are confident their proposed experiment will yield positive results.

Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity’s first interstellar voyage. Credit: breakthroughinitiatives.org

“We have proposed a simple experiment where the presence of the Unruh thermal bath is codified in the Larmor radiation emitted from an accelerated charge,” they state. “Then, we carried out a straightforward classical-electrodynamics calculation (checked by a quantum-field-theory one) to confirm it by ourselves. Unless one challenges classical electrodynamics, our results must be virtually considered as an observation of the Unruh effect.”

If the experiments should prove successful, and the Unruh effect is proven to exist, it would certainly have consequences for any future deep-space missions that rely on advanced propulsion systems. Between Project Starshot, and any proposed mission that would involve sending a crew to another star system, the added effects of a “fog of photons” and a “thermal bath” will need to be factored in.

Further Reading: arXiv, ScienceMag

Forget Mars, Now You Can Kickstart an Antimatter Propulsion System to Another Star!

When it comes to the future of space exploration, one of the biggest questions is, “how and when will we travel to the nearest star?” And while space agencies have been pondering this question and coming up with proposals for decades, none of them have advanced beyond the theory stage. For the most part, their efforts has been focused on possible missions to Mars and the outer Solar System.

But there are some people, like Dr. Gerald Jackson, who are working towards making an interstellar mission possible in the near future. He and his research team, which have been funded by NASA in the past, are looking to create an antimatter engine that will be capable of reaching (or exceeding) 5% the speed of light. Towards this end, they have launched a Kickstarter campaign to fund their efforts.

As advanced propulsion concepts go, antimatter has quite a lot going for it. As propulsion goes, it has the highest specific energy of any known method, 100 times more than fission/fusion reactions, and 10 billion times more than chemical propellants. It is also the most fuel-efficient, requiring mere milligrams of antimatter to produce the same amount of energy as tons of chemical fuel.

In 2002, he co-founded a limited-liability company (HBar Technologies) for the sake of developing commercial markets for antimatter. In 2002, NASA’s Institute for Advanced Concepts (NIAC) awarded Dr. Jackson and his company $75,000 to develop a mission concept that could traverse 250 AUs of space within 10 years time, and with a fuel supply of 10 kg.

These specifications essentially called for the creation of an antimatter rocket that could travel as far as the heliopause within a decade’s time. The result was a propulsion concept that relied on a beam that would fire focused antiprotons onto a sail to generate propulsion. This sail would measure 5 meters in diameter and be composed of a carbon backing on one side and uranium foil on the other (measuring 15 and 296 microns thick, respectively).

The solar system and its nearby galactic neighborhood are illustrated here on a logarithmic scale extending (from < 1 to) 1 million Astornomical Units (AU). Credit: NASA/JPL
Illustration of the solar system and its nearby galactic neighborhood on a logarithmic scale extending (from < 1 to) 1 million AU. Credit: NASA/JPL

When a pulse of antiprotons is annihilated against a small section of the uranium side, the resulting fission causes momentum. As Dr. Jackson explained to Universe Today via email:

“Note that antiprotons have a negative electrical charge, similar to an electron. When the antiprotons enter the sail, they displace an electron orbiting an uranium nucleus. Because antiprotons and electrons do not share any quantum numbers, the antiproton immediately cascades down into the atomic ground state, causing a high probability of interaction between the antiproton and either a proton or neutron within the nucleus.

“On average, a fission event results in the creation of two daughter nuclei of roughly equal mass. These daughters travel in opposite directions with a kinetic energy of 1 MeV per proton or neutron. Because the daughters are charged, the one travelling further into the sail is absorbed and transfers is forward momentum. The other daughter flies into space with an exhaust velocity of 4.6% of lightspeed. This selective transfer of momentum is thrust.”

Unfortunately, due to the budget environment of the time, the NIAC was forced to cancel its funding after a second round had been granted. Because of this, Dr. Jackson and his colleagues are now seeking public support so that they may finish their work on the experimental sail and prepare it for exposure to an antiproton beam.

Diagram showing Hbar's concept for a antimatter-driven propulsion system. Credit: antimatterdrive.org
Diagram showing Hbar’s concept for a antimatter-driven propulsion system. Credit: antimatterdrive.org

Much like Project Starshot (whom they acknowledge on their campaign page), Jackson and his team are looking to produce an interstellar mission proposal that does not involve shortcuts (i.e. warp drive, wormholes, star gates, etc.). Starshot, as you may recall, calls for a wafer craft and a laser-driven lightsail that would be capable of reaching speeds of up to 20% the speed of light, thus making the journey to Alpha Centauri in 20 years.

In the same vein, a antiproton-driven sail that could reach speeds of 5% the speed of light or more would be capable of making it to Alpha Centauri (or Proxima Centauri) in about 90 years time. All the while, the science behind it would remain within the realm of established physics, being consistent with Newton’s Laws of Motion and Einstein’s Theory of Special Relativity.

“The revolutionary aspect of the antimatter-driven sail is that the antimatter is not the fuel, but rather the spark plug that initiates fission reactions,” said Jackson. “Because the fission reactions can produce thrust without heavy shielding or other structures, the mass of the propulsion system can be comparable to the mass of the instrument package.”

Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity's first interstellar voyage. Credit: breakthroughinitiatives.org
Project Starshot, an initiative sponsored by the Breakthrough Foundation, is another concept for making humanity’s first interstellar voyage. Credit: breakthroughinitiatives.org

To see their project through, Jackson and his colleagues are hoping to raise $200,000. Should they prove successful, they hope to mount follow-up campaigns to finance a series of validation experiments, storage demonstrations, and mission details. In the end, their goal is nothing less than making antimatter propulsion a reality, which they hope will one day lead interstellar mission.

“We expect that these campaigns will provide the data needed to convince people to fund full scale antimatter production and an actual mission to a nearby solar system,” Jackson added. “The goal of those early interstellar missions is to provide information about these other solar systems, such as whether they are habitable or inhabited.  If the latter, we will want to study or interact with those life forms in follow-on missions.  If habitable and not inhabited, we need sufficient information to assure the success of a manned migratory mission.”

As of the penning of this article, Jackson and his colleagues have raised $672 of their $200,000 goal. However, the campaign launched only a few days ago and will remain open for another 25 days. For those interesting in following their progress, or have an interest in donating to their cause, check out the links below.

Is Alpha Centauri The Best Place To Look For Aliens?

For generations, human beings have fantasized about the possibility of finding extra-terrestrial life. And with our ongoing research efforts to discover new and exciting extrasolar planets (aka. exoplanets) in distant star systems, the possibility of actually visiting one of these worlds has received a real shot in the arm. Unfortunately, given the astronomical distances involved, not to mention the cost of mounting an expedition, doing so presents numerous significant challenges.

However, Russian billionaire Yuri Milner and the Breakthrough Foundation – an international organization committed to exploration and scientific research –  is determined to mount an interstellar mission to Alpha Centauri, our closest stellar neighbor, in the coming years. With the backing of such big name sponsors as Mark Zuckerberg and Stephen Hawking, his latest initiative (named “Project Starshot“) aims to send a tiny spacecraft to the Alpha Centauri system to search for planets and signs of life.

Continue reading “Is Alpha Centauri The Best Place To Look For Aliens?”

The Physics Behind “Interstellar’s” Visual Effects Was So Good, it Led to a Scientific Discovery

While he was working on the film Interstellar, executive producer Kip Thorne was tasked with creating the black hole that would be central to the plot. As a theoretical physicist, he also wanted to create something that was truly realistic and as close to the real thing as movie-goers would ever see.

On the other hand, Christopher Nolan – the film’s director – wanted to create something that would be a visually-mesmerizing experience. As you can see from the image above, they certainly succeeded as far as the aesthetics were concerned. But even more impressive was how the creation of this fictitious black hole led to an actual scientific discovery.

Continue reading “The Physics Behind “Interstellar’s” Visual Effects Was So Good, it Led to a Scientific Discovery”

Mr. Fusion? Compact Fusion Reactor Will be Available in 5 Years Says Lockheed-Martin

The Farnsworth Fusor; Pons and Fleishmann. It seems the trail to fusion energy has long gone cold — stone cold, that is, and not cold as in cold fusion. Despite the promise of fusion providing a sustainable and safe energy source, fusion reactors are not a dime a dozen and they won’t be replacing coal fired power plants any time soon. Or will they? Lockheed-Martin Skunk Works announced a prototype compact fusion reactor that could be ready within five years. This revelation has raised eyebrows and sparked moments of enthusiasm.

But, let’s considers this story and where it all fits in both the history and future.

For every Skunk Works project that has made the runway such as the Stealth Fighter or SR-71 Blackbird, there are untold others that never see the light of day. This adds to the surprise and mystery of Lockheed-Martin’s willingness to release images and a detailed narrative describing a compact fusion reactor project. The impact that such a device would have on humanity can be imagined … and at the same time one imagines how much is unimaginable.

Lockheed-Martin engineers in the Skunkworks prepare a vessel, one component of an apparatus that they announced will lead to nuclear fusion in a truck-sized reactor within 5 years. An international effort is underway in Europe to create the worlds first practical tokamak fusion reactor, a much larger and costlier design that has never achieved the long sought "breakeven" point. (Photo Credit: Lockheed-Martin)
Lockheed-Martin engineers in the Skunkworks prepare a vessel, one component of an apparatus that they announced will lead to nuclear fusion in a truck-sized reactor within 5 years. An international effort is underway in Europe to create the world’s first practical tokamak fusion reactor, a much larger and costlier design that has never achieved the long sought “breakeven” point. (Photo Credit: Lockheed-Martin)

The program manager of the Skunk Works’ compact fusion reactor experiment is Tom Maguire. Maguire and his team places emphasis on the turn-around time for modifying and testing the compact fusion device. With the confidence they are expressing in their design and the ability to quickly build, test and modify, they are claiming only five years will be needed to reach a prototype.

What exactly the prototype represents was left unexplained, however. Maguire continues by saying that in 10 years, the device will be seen in military applications and in 20 years it will be delivered to the world as a replacement for the dirty energy sources that are in use today. Military apps at 10 years means that the device will be too expensive initially for civilian operations but such military use would improve performance and lower costs which could lead to the 20 year milestone moment if all goes as planned.

Their system uses magnetic confinement, the same basic principle behind the tokamak toroidal plasma confinement system that has received the greatest attention and government funding for over 50 years.

The ITER Tokamak Fusion Reactor is expected to begin operational testing in 2020 and begin producing deuterium-tritium fusion reactions in 2027. (Credits: ITER, Illus. T.Reyes)
The ITER Tokamak Fusion Reactor is expected to begin operational testing in 2020 and begin producing deuterium-tritium fusion reactions in 2027. (Credits: ITER, Illus. T.Reyes)

The International Thermonuclear Experimental Reactor (ITER) is currently under construction in Europe under the assumption that it will be the first net energy producing fusion generator ever. It is funded by the European Union, India, Japan, People’s Republic of China, Russia, South Korea and the United States. But there are cost over-runs and its price has gone from $5 billion to $50 billion.

ITER is scheduled to begin initial testing in 2019 about the time Lockheed-Martin’s compact fusion reactor prototype is expected. If Lockheed-Martin succeeds in their quest, they will effectively have skunked ITER and laid to waste a $50 billion international effort at likely 1/1000th the cost.

There are a few reasons Lockheed-Martin has gone out on a limb. Consider the potential. One ton of Uranium used in Fission reactors has as much energy as 1,500 tons of coal. But fission reactors produce radioactive waste and are a finite resource without breeder reactors, themselves a nuclear proliferation risk. Fusion produces 3 to 4 times more energy per reaction than fission. Additionally, the fuel — isotopes of hydrogen — is available from sea water — which is nearly limitless — and the byproducts are far less radioactive than with fission. Fusion generators once developed could provide our energy needs for millions of years.

More pragmatically, corporations promote their R&D. They are in a constant state of competition. They present a profile that ranges from the practical to the cutting edge to instill confidence in their Washington coffers. Furthermore, their competitors have high profile individuals and projects. A fusion project demonstrates that Lockheed-Martin is doing more than creating better mouse-traps.

To date, no nuclear fusion reactor has achieved breakeven. This is when the fusion device outputs as much energy as is input to operate it. Magnetic confinement such as the various tokamak designs, Lawrence Livermore’s laser-based inertial confinement method, and even the simple Philo Farnsworth Fusor can all claim to be generating energy from fusion reactions. They are just all spending more energy than their devices output.

An example of a homemade Fusor. Originally invented in the 1960s by the inventor of the television, Philo Farnsworth. (Credit: Wikipedia, W.Jack)
An example of a homemade Fusor. Originally invented in the 1960s by the inventor of the television, Philo Farnsworth. (Credit: Wikipedia, W.Jack)

The fusor, invented in the 1960s by Farnsworth and Hirsh, is a electrostatic plasma confinement system. It uses electric fields to confine and accelerate ions through a central point at which some ions will collide with sufficient energy to fuse. Although the voltage needed is readily achieved by amateurs – about 4000 volts – not uncommon in household devices, no fusor has reached breakeven and theoretically never will. The challenge to reaching breakeven involves not just energy/temperature but also plasma densities. Replicating conditions that exist in the core of stars in a controllable way is not easy. Nevertheless, there is a robust community of “fusioneers” around the world and linked by the internet.

Mr Fusion, the compact fusion reactor that drove the 21st Century version of the DeLorian in Back to the Future. The movie trilogy grossed $1 billion at the box office. Mr Fusion could apparently function off of any water bearing material. (Credit: Universal Pictures)
Mr Fusion, the compact fusion reactor that drove the 21st Century version of the DeLorean in Back to the Future. The movie trilogy grossed $1 billion at the box office. Mr Fusion could apparently function off of any water bearing material. (Credit: Universal Pictures)

It remains to be seen who, what and when a viable fusion reactor will be demonstrated. With Lockheed-Martin’s latest announcement, once again, fusion energy is “just around the corner.” But many skeptics remain who will quickly state that commercial fusion energy remains 50 years in the future. So long as Maguire’s team meets milestones with expected performance improvements, their work will go on. The potential of fusion energy remains too great to dismiss categorically.

Source: Lockheed-Martin Products Page, Compact Fusion

When Will We Become Interstellar?

Dr. Ian O’Neill is one of the coolest scientists we know, so we sat him down at the YouTube spaces and asked him a real zinger – when will we humans become an interstellar race, like the ones we’re used to seeing on Star Trek? Here’s what he had to say to us!
Continue reading “When Will We Become Interstellar?”

Navigating the Solar System Using Pulsars as GPS

Picture the scene: It’s the not too distant future and humanity has started to construct colonies and habitats all across our solar system. We’re gearing up to take that next big step into the unknown – actually leaving the cozy protection of the Sun’s heliosphere and venturing into interstellar space. Before this future can happen, however, there’s an important thing which is often overlooked in discussions on this subject.

Navigation.

Just as sailors once used the stars to navigate the sea, space travelers may be able to use the stars to navigate the solar system. Except that this time, the stars we’d use will be dead ones. A specific class of neutron stars known as pulsars, defined by the repeated pulses of radiation they emit. The trick, according to a recent paper, may be to use pulsars as a form of interplanetary – and possibly even interstellar – GPS.

Theories and ideas on spacecraft engines are plentiful. Foundations such as Icarus Interstellar keenly advocate the development of new propulsion systems, with some systems such as the VASIMR thrusters appearing rather promising. Meanwhile, fusion rockets are expected to be able to take passengers on a round trip from Earth to Mars in just 30 days, and researchers elsewhere are working on real life warp drives, not unlike the ones we all know and love from the movies.

Interplanetary GPS

For Voyager 2, out on the edge of our Solar system, conventional navigation methods don't work too well. Credit: NASA
For Voyager 2, out on the edge of our Solar system, conventional navigation methods don’t work too well. Credit: NASA

But navigation is just as important. After all, space is mind-meltingly vast and mostly empty. The prospect of getting lost out in the emptiness is, frankly, terrifying.

To date, this hasn’t really been a problem, particularly seeing as we’ve only sent a small handful of craft past Mars. As a result, we currently use a messy mishmash of techniques to keep track of spacecraft from here on Earth – essentially tracking them with telescopes while relying heavily on their planned trajectory. This is also only as accurate as our instruments here on Earth are, meaning that as a craft gets more distant, our idea of where exactly it is becomes increasingly less accurate.

This is all well and good when we only have a few craft to track, but when space travel becomes more easily attainable and human passengers are involved, routing everything through Earth will start to become more and more difficult. This is particularly the case if we’re planning on leaving the confines of our home star – Voyager 2 is presently over 14 light hours away, meaning that Earth-based transmissions take over half a day to reach it.

Navigating Earth with modern technology is quite simple thanks to the array of GPS satellites we have in orbit around our world. Those satellites are constantly transitting signals which are, in turn, received by the GPS unit you may have on your car dashboard or in your pocket. As with all other electromagnetic transmissions, those signals travel at the speed of light, giving a slight delay between when they were transmitted and when they’re received. By using the signals from 4 or more satellites and timing those delays, a GPS unit can pinpoint your location on the surface of Earth with remarkable accuracy.

The Icarus Pathfinder starship passing by Neptune. Credit: Adrian Mann
The Icarus Pathfinder starship passing by Neptune. Credit: Adrian Mann

The pulsar navigation system proposed by Werner Becker, Mike Bernhardt, and Axel Jessner at the Max Planck Institute, works in a very similar way, using the pulses emitted by pulsars. By knowing the initial position and velocity of your spacecraft, recording those pulses, and treating the Sun as a fixed reference point, you can calculate your exact location inside the solar system.

Considering the Sun to be fixed this way is technically referred to as an inertial reference frame, and if you compensate for the motion of the Sun through our galaxy, the system still works perfectly well when leaving the Solar system! All you need is to keep track of a minimum of 3 pulsars (ideally 10, for the most accurate results), and you can pinpoint your location with surprising accuracy!

Interestingly enough, the idea of using pulsars as navigation beacons dates all the way back to 1974, notably not long after Carl Sagan had used pulsars to show Earth’s location on the plaques attached to the Pioneer 10 and 11 space probes. If Project Daedalus had ever been constructed, it might have been equipped with a system not unlike the one described here.

Packing for long haul

Becker and his colleagues looked at the different types of pulsar visible in the sky, and picked out a type known as rotation-powered pulsars as the best type to use for a galactic positioning system. In particular, a sub-type of these known as millisecond pulsars are ideal. Being older than most pulsars they have weak magnetic fields, meaning they take a long time to slow down their spin rates – helpful as strongly magnetised pulsars can sometimes change their rotation speed without warning.

An x-ray image of the Vela pulsar, one of the brightest known millisecond pulsars. Credit: NASA/CXC/PSU/G.Pavlov et al.
An x-ray image of the Vela pulsar, one of the brightest known millisecond pulsars. Credit: NASA/CXC/PSU/G.Pavlov et al.

With countless pulsars to choose from, the question turns to how you might equip your spacecraft to track them. Pulsars are easiest to spot in either x-rays or radio waves, so there’s a little choice as to which may be better to use. Essentially, it all turns out to be a question of how large your spacecraft is.

Smaller vehicles, more akin to modern spacecraft, would be best off using x-rays to track pulsars. X-ray mirrors, like the ones used in certain orbiting space telescopes are compact and lightweight, meaning that a few could be added for a navigation system without increasing the overall mass of the craft all that much. They may have the minor disadvantage that they may be easily damaged by an x-ray source which is too bright, this wouldn’t be a problem except under some unfortunate circumstances.

On the other hand, if you’re piloting a large space ship between planets or even stars, you would likely be better using radio waves. In radio frequencies, we know a lot more about the way in which pulsars work, as well as being able to measure them with a higher degree of accuracy. The only drawback there is that the radio telescopes you’d need to install on your ship would require an area of at least 150 m². But then, if you happened to be flying a starship, that kind of size probably wouldn’t make much difference.

It’s interesting to bear in mind the way that astronomers frequently use the analogy of pulsars being “like lighthouses” when explaining why they appear to pulse. If we someday find ourselves using them as actual navigation aids, that analogy may take on a whole new meaning!

You can read the team’s paper here.

The Icarus Starfinder, shown leaving the Solar system. Ships like this may be equipped with a pulsar navigation system. Credit: Adrian Mann
The Icarus Starfinder, shown leaving the Solar system. Ships like this may be equipped with a pulsar navigation system. Credit: Adrian Mann

Images are used here with kind permission from Adrian Mann of Icarus Interstellar, whose full gallery is viewable online at bisbos.com

What is Interstellar Space?

Glittering Metropolis of Stars

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The boundary of what is known, that place known as the great frontier, has always intrigued and enticed us. The mystery of the unknown, the potential for discovery, the fear, the uncertainty; that place that exists just beyond the edge has got it all! At one time, planet Earth contained many such places for explorers, vagabonds and conquerors. But unfortunately, we’ve run out of spaces to label “here be dragons” here at home. Now, humanity must look to the stars to find such places again. These areas, the vast stretches of space that fall between the illuminated regions where stars sit, is what is known as Interstellar Space. It can be the space between stars but also can refer to the space between galaxies.

On the whole, this area of space is defined by its emptiness. That is, there are no stars or planetary bodies in these regions that we know of. That does not mean, however, that there is absolutely nothing there. In fact, interstellar areas do contain quantities of gas, dust, and radiation. In the first two cases, this is what is known as interstellar medium (or ISM), the matter that fills interstellar space and blends smoothly into the surrounding intergalactic space. The energy that occupies the same volume, in the form of electromagnetic radiation, is known as the interstellar radiation field. On the whole, the ISM is thought to be made up primarily of plasma (aka. ionized hydrogen gas) because its temperature appears to be high by terrestrial standards.

The nature of the interstellar medium has received the attention of astronomers and scientists over the centuries. The term first appeared in print in the 17th century in the works of Sir Francis Bacon and Robert Boyle, both of whom were referring to the spaces that fell between stars. Before the development of electromagnetic theory, early physicists believed that space must be filled with an invisible “aether” in order for light to pass through it. It was not until the 20th century though that deep photographic imaging and spectroscopy that scientists were able to postulate that matter and gas existed in these regions. The discovery of cosmic waves in 1912 was a further boon, leading to the theory that interstellar space was pervaded by them. With the advent of ultraviolet, x-ray, microwave, and gamma ray detectors, scientists have been able to “see” these kinds of energy at work in interstellar space and confirm their existence.

Many satellites have been launched with the intention of sending back information from interstellar space. These include the Voyager 1 and 2 spacecraft which have cleared the known boundaries of the Solar System and passed into the heliopause. They are expected to continue to operate for the next 25 to 30 years, sending back data on magnetic fields and interstellar particles.

We have written many articles about interstellar space for Universe Today. Here’s an article about deep space, and here’s an article about interstellar space travel.

If you’d like more information on the Interstellar Space, here’s a link to Voyager’s Interstellar Mission Page, and here’s the homepage for Interstellar Science.

We’ve recorded an episode of Astronomy Cast all about Interstellar Travel. Listen here, Episode 145: Interstellar Travel.

Sources:
http://en.wikipedia.org/wiki/Interstellar_space#Interstellar
http://en.wikipedia.org/wiki/Interstellar_medium
http://www.seasky.org/solar-system/interstellar-space.html
http://en.wikipedia.org/wiki/Electromagnetic_radiation
http://en.wikipedia.org/wiki/Heliopause#Heliopause