Monthly Archives: April 2021

For most people, getting to the stars is nothing more than a dream. On April 28, 2001, Dennis Tito achieved that lifelong goal but he wasnt a typical astronaut. Tito, a wealthy businessman, paid US$20 million for a seat on a Russian Soyuz spacecraft to be the first tourist to visit the International Space Station. Only seven people have followed suit in the 20 years since, but that number is poised to double in the next 12 months alone.

NASA has long been hesitant to play host to space tourists, so Russia looking for sources of money post-Cold War in the 1990s and 2000s has been the only option available for those looking for this kind of extreme adventure. However, it seems the rise of private space companies is going to make it easier for regular people to experience space.

From my perspective as a space policy analyst, I see the beginning of an era in which more people can experience space. With companies like SpaceX and Blue Origin hoping to build a future for humanity in space, space tourism is a way to demonstrate both the safety and reliability of space travel to the general public.

The Development of Space Tourism

Flights to space like Dennis Titos are expensive for a reason. A rocket must burn a lot of costly fuel to travel high and fast enough to enter Earths orbit.

Another cheaper possibility is a suborbital launch, with the rocket going high enough to reach the edge of space and coming right back down. While passengers on a suborbital trip experience weightlessness and incredible views, these launches are more accessible.

The difficulty and expense of either option has meant that, traditionally, only nation-states have been able to explore space. This began to change in the 1990s as a series of entrepreneurs entered the space arena. Three companies led by billionaire CEOs have emerged as the major players: Virgin Galactic, Blue Origin and SpaceX. Though none have taken paying, private customers to space, all anticipate doing so in the very near future.

British billionaire Richard Branson has built his brand on not just business but also his love of adventure. In pursuing space tourism, Branson has brought both of those to bear. He established Virgin Galactic after buying SpaceShipOne - a company that won the Ansari X-Prize by building the first reusable spaceship. Since then, Virgin Galactic has sought to design, build and fly a larger SpaceShipTwo that can carry up to six passengers in a suborbital flight.

The going has been harder than anticipated. While Branson predicted opening the business to tourists in 2009, Virgin Galactic has encountered some significant hurdles including the death of a pilot in a crash in 2014. After the crash, engineers found significant problems with the design of the vehicle, which required modifications.

Elon Musk and Jeff Bezos, respective leaders of SpaceX and Blue Origin, began their own ventures in the early 2000s.

Musk, fearing that a catastrophe of some sort could leave Earth uninhabitable, was frustrated at the lack of progress in making humanity a multiplanetary species. He founded SpaceX in 2002 with the goal of first developing reusable launch technology to decrease the cost of getting to space. Since then, SpaceX has found success with its Falcon 9 rocket and Dragon spacecraft. SpaceXs ultimate goal is human settlement of Mars sending paying customers to space is an intermediate step. Musk says he hopes to show that space travel can be done easily and that tourism might provide a revenue stream to support development of the larger, Mars-focused Starship system.

Bezos, inspired by the vision of physicist Gerard ONeill, wants to expand humanity and industry not to Mars, but to space itself. Blue Origin, established in 2004, has proceeded slowly and quietly in also developing reusable rockets. Its New Shepard rocket, first successfully flown in 2015, will eventually offer tourists a suborbital trip to the edge of space, similar to Virgin Galactics. For Bezos, these launches represent an effort at making space travel routine, reliable and accessible to people as a first step to enabling further space exploration.

Outlook for the Future

Now, SpaceX is the only option for someone looking to go into space and orbit the Earth. It currently has two tourist launches planned. The first is scheduled for as early as September 2021, funded by billionaire businessman Jared Isaacman. The other trip, planned for 2022, is being organized by Axiom Space. These trips will be costly, at $55 million for the flight and a stay on the International Space Station. The high cost has led some to warn that space tourism and private access to space more broadly might reinforce inequality between rich and poor.

Blue Origins and Virgin Galactics suborbital trips are far more reasonable in cost, with both priced between $200,000 and $250,000. Blue Origin appears to be the nearest to allowing paying customers on board, saying after a recent launch that crewed missions would be happening soon. Virgin Galactic continues to test SpaceShipTwo, but no specific timetable has been announced for tourist flights.

Though these prices are high, it is worth considering that Dennis Titos $20 million ticket in 2001 could pay for 100 flights on Blue Origin soon. The experience of viewing the Earth from space, though, may prove to be priceless for a whole new generation of space explorers.

Wendy Whitman Cobbis a professor of strategy and security studies at theU.S. Air Force School of Advanced Air and Space Studies

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Space Tourism 20 Years in the Making Is Finally Ready for Launch - Nextgov

The closest star to Earth is Proxima Centauri. It is about 4.25 light-years away, or about 25 trillion miles (40 trillion km). The fastest ever spacecraft, the now- in-space Parker Solar Probe will reach a top speed of 450,000 mph. It would take just 20 seconds to go from Los Angeles to New York City at that speed, but it would take the solar probe about 6,633 years to reach Earths nearest neighboring solar system.

If humanity ever wants to travel easily between stars, people will need to go faster than light. But so far, faster-than-light travel is possible only in science fiction.

In Issac Asimovs Foundation series, humanity can travel from planet to planet, star to star or across the universe using jump drives. As a kid, I read as many of those stories as I could get my hands on. I am now a theoretical physicist and study nanotechnology, but I am still fascinated by the ways humanity could one day travel in space.

Some characters like the astronauts in the movies Interstellar and Thor use wormholes to travel between solar systems in seconds. Another approach familiar to Star Trek fans is warp drive technology. Warp drives are theoretically possible if still far-fetched technology. Two recent papers made headlines in March when researchers claimed to have overcome one of the many challenges that stand between the theory of warp drives and reality.

But how do these theoretical warp drives really work? And will humans be making the jump to warp speed anytime soon?

Physicists current understanding of spacetime comes from Albert Einsteins theory of General Relativity. General Relativity states that space and time are fused and that nothing can travel faster than the speed of light. General relativity also describes how mass and energy warp spacetime hefty objects like stars and black holes curve spacetime around them. This curvature is what you feel as gravity and why many spacefaring heroes worry about getting stuck in or falling into a gravity well. Early science fiction writers John Campbell and Asimov saw this warping as a way to skirt the speed limit.

What if a starship could compress space in front of it while expanding spacetime behind it? Star Trek took this idea and named it the warp drive.

In 1994, Miguel Alcubierre, a Mexican theoretical physicist, showed that compressing spacetime in front of the spaceship while expanding it behind was mathematically possible within the laws of General Relativity. So, what does that mean? Imagine the distance between two points is 10 meters (33 feet). If you are standing at point A and can travel one meter per second, it would take 10 seconds to get to point B. However, lets say you could somehow compress the space between you and point B so that the interval is now just one meter. Then, moving through spacetime at your maximum speed of one meter per second, you would be able to reach point B in about one second. In theory, this approach does not contradict the laws of relativity since you are not moving faster than light in the space around you. Alcubierre showed that the warp drive from Star Trek was in fact theoretically possible.

Proxima Centauri here we come, right? Unfortunately, Alcubierres method of compressing spacetime had one problem: it requires negative energy or negative mass.

Alcubierres warp drive would work by creating a bubble of flat spacetime around the spaceship and curving spacetime around that bubble to reduce distances. The warp drive would require either negative mass a theorized type of matter or a ring of negative energy density to work. Physicists have never observed negative mass, so that leaves negative energy as the only option.

To create negative energy, a warp drive would use a huge amount of mass to create an imbalance between particles and antiparticles. For example, if an electron and an antielectron appear near the warp drive, one of the particles would get trapped by the mass and this results in an imbalance. This imbalance results in negative energy density. Alcubierres warp drive would use this negative energy to create the spacetime bubble.

But for a warp drive to generate enough negative energy, you would need a lot of matter. Alcubierre estimated that a warp drive with a 100-meter bubble would require the mass of the entire visible universe.

In 1999, physicist Chris Van Den Broeck showed that expanding the volume inside the bubble but keeping the surface area constant would reduce the energy requirements significantly, to just about the mass of the sun. A significant improvement, but still far beyond all practical possibilities.

Two recent papers one by Alexey Bobrick and Gianni Martire and another by Erik Lentz provide solutions that seem to bring warp drives closer to reality.

Bobrick and Martire realized that by modifying spacetime within the bubble in a certain way, they could remove the need to use negative energy. This solution, though, does not produce a warp drive that can go faster than light.

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Independently, Lentz also proposed a solution that does not require negative energy. He used a different geometric approach to solve the equations of General Relativity, and by doing so, he found that a warp drive wouldnt need to use negative energy. Lentzs solution would allow the bubble to travel faster than the speed of light.

It is essential to point out that these exciting developments are mathematical models. As a physicist, I wont fully trust models until we have experimental proof. Yet, the science of warp drives is coming into view. As a science fiction fan, I welcome all this innovative thinking. In the words of Captain Picard, things are only impossible until they are not.

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Warp drives: Physicists give chances of faster-than-light space travel a boost - The Conversation US

This article was originally published atThe Conversation.The publication contributed the article to Space.com'sExpert Voices: Op-Ed & Insights.

Sam Baron, Associate professor, Australian Catholic University

In 1994, physicist Miguel Alcubierreproposeda radical technology that would allow faster than light travel: thewarp drive, a hypothetical way to skirt around the universe's ultimate speed limit by bending the fabric of reality.

It was an intriguing idea even NASA has beenresearchingit at the Eagleworks laboratory but Alcubierres proposal contained problems that seemed insurmountable. Now, a recentpaperby US-based physicists Alexey Bobrick and Gianni Martire has resolved many of those issues andgeneratedalotofbuzz.

But while Bobrick and Martire have managed to substantially demystify warp technology, their work actually suggests that faster-than-light travel will remain out of reach for beings like us, at least for the time being.

There is, however, a silver lining: warp technology may have radical applications beyond space travel.

Related: 'Impossible' EmDrive Space Thruster May Really Be Impossible

The story of warp drives starts with Einstein's crowning achievement: general relativity. The equations of general relativity capture the way in which spacetime the very fabric of reality bends in response to the presence of matter and energy which, in turn, explains how matter and energy move.

General relativity places two constraints on interstellar travel. First, nothing can be accelerated past the speed of light (around 300,000 km per second). Even travelling at this dizzying speed it would still take us four years to arrive at Proxima Centauri, the nearest star to our Sun.

Second, the clock on a spaceship travelling close to the speed of light would slow down relative to a clock on Earth (this is known as time dilation). Assuming a constant state of acceleration, this makes it possible to travel the stars. One can reach a distant star that is 150 light-years away within one's lifetime. The catch, however, is that upon ones return more than 300 years will have passed on Earth.

Related: Warp Speed and the hype of hyperspace

This is where Alcubierre came in. He argued that the mathematics of general relativity allowed for "warp bubbles" regions where matter and energy were arranged in such a way as to bend spacetime in front of the bubble and expand it to the rear in a way that allowed a flat area inside the bubble to travel faster than light.

Read more:Don't stop me now! Superluminal travel in Einstein's universe

To get a sense of what "flat" means in this context, note that spacetime is sort of like a rubber mat. The mat curves in the presence of matter and energy (think of putting a bowling ball on the mat). Gravity is nothing more than the tendency objects have to roll into the the dents created by things like stars and planets. A flat region is like a part of the mat with nothing on it.

Such a drive would also avoid the uncomfortable consequences of time dilation. One could potentially make a round trip into deep space and still be greeted by ones nearest and dearest at home.

How does Alcubierre's device work? Here discussion often relies on analogies, because the maths is so complex.

Imagine a rug with a cup on it. You're on the rug and you want to get to the cup. You could move across the rug, or tug the rug toward you. The warp drive is like tugging on spacetime to bring your destination closer.

But analogies have their limits: a warp drive doesn't really drag your destination toward you. It contracts spacetime to make your path shorter. Theres just less rug between you and the cup when you switch the drive on.

Alcubierres suggestion, while mathematically rigorous, is difficult to understand at an intuitive level. Bobrick and Martire's work is set to change all that.

Bobrick and Martire show that any warp drive must be a shell of material in a constant state of motion, enclosing a flat region of spacetime. The energy of the shell modifies the properties of the spacetime region inside it.

This might not sound like much of a discovery, but until now it was unclear what warp drives might be, physically speaking. Their work tells us that a warp drive is, somewhat surprisingly, like a car. A car is also a shell of energy (in the form of matter) that encloses a flat region of spacetime. The difference is that getting inside a car does not make you age faster. That, however, is the kind of thing a warp drive might do.

Using their simple description, Bobrick and Martire demonstrate a method for using Einsteins general relativity equations to find spacetimes that allow for arrangements of matter and energy that would act as warp bubbles. This gives us a mathematical key for finding and classifying warp technologies.

Their work manages to address one of the core problems for warp drives. To make the equations balance, Alcubierres device runs on negative energy but we are yet to discover any viable sources of negative energy in the real world.

Worse, the negative energy requirements of Alcubierres device are immense. By some estimates, the entire energy in the known universe would be needed (though later work brings the number down a bit).

Bobrick and Martire show a warp drive could be made from positive energy (i.e. normal energy) or from a mixture of negative and positive energy. That said, the energy requirements would still be immense.

If Bobrick and Martire are right, then a warp drive is just like any other object in motion. It would be subject to the universal speed limit enforced by general relativity after all, and it would need some kind of conventional propulsion system to make it accelerate.

The news gets worse. Many kinds of warp drive can only modify the spacetime inside in a certain way: by slowing down the clock of the passenger in exactly the way that makes a trip into deep space a problem.

Bobrick and Martire do show that some warp drives could travel faster than light, but only if they are created already travelling at that speed which is no help for any ordinary human hoping for a bit of interstellar tourism.

Remember that a warp drive can modify the region of flat spacetime it encloses. It can, in particular, speed up or slow down a clock inside the drive.

Consider what it would mean to have such an object available. Want to put someone with a terminal illness on ice? Stick them in a warp drive and slow their clock down. From their perspective, a few years will pass, while a hundred years will pass on Earth time enough to find a cure.

Read more:The art and beauty of general relativity

Want to grow your crops overnight? Stick them in a warp drive and speed the clock up. A few days will pass for you, and a few weeks will pass for your seedlings.

There are even more exotic possibilities: by rotating the spacetime inside a drive one may be able to produce a battery capable of holding huge amounts of energy.

Faster-than-light travel remains a distant dream. But warp technology would be revolutionary in its own right.

This article is republished fromThe Conversationunder a Creative Commons license. Read theoriginal article.

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New warp drive research dashes faster than light travel dreams, but reveals stranger possibilities - Space.com