Why sub-orbital flights aren’t going to happen anytime soon

Virgin Galactic sub-orbital space plane

The hype over supersonic and sub-orbital flying has been going on for at least 30-40 years, the promise being that people will be able to go anywhere in the world in a matter of hours. The usual example being London-Sydney in a few hours.

But as Charlie Stross explains in this excellent article, hypersonic and sub-orbital travel will be prohibitively expensive however it is done.

Let’s start with a simple normative assumption; that sub-orbital spaceplanes are going to obey the laws of physics. One consequence of this is that the amount of energy it takes to get from A to B via hypersonic airliner is going to exceed the energy input it takes to cover the same distance using a subsonic jet, by quite a margin. Yes, we can save some fuel by travelling above the atmosphere and cutting air resistance, but it’s not a free lunch: you expend energy getting up to altitude and speed, and the fuel burn for going faster rises nonlinearly with speed. Concorde, flying trans-Atlantic at Mach 2.0, burned about the same amount of fuel as a Boeing 747 of similar vintage flying trans-Atlantic at Mach 0.85 … while carrying less than a quarter as many passengers.

Rockets aren’t a magic technology. Neither are hybrid hypersonic air-breathing gadgets like Reaction Engines’ Sabre engine. It’s going to be a wee bit expensive. But let’s suppose we can get the price down far enough that a seat in a Mach 5 to Mach 10 hypersonic or sub-orbital passenger aircraft is cost-competitive with a high-end first class seat on a subsonic jet. Surely the super-rich will all switch to hypersonic services in a shot, just as they used Concorde to commute between New York and London back before Airbus killed it off by cancelling support after the 30-year operational milestone?

Well, no.

Quite. How are you going to transport these (mega-rich) people from the hypersonic terminal somewhere far away from civilization to the city they want to travel to? And how are you going to intercept a hypersonic jet which has been commandeered by terrorists?

None of it makes economic or logistical sense.

Concorde, from Wikipedia

The biggest problem with Concorde was the sonic boom it generated, which meant that it could only travel across oceans supersonically, When it was over land, Concorde was sub-sonic and still managed to rattle windows below it because of the enormous noise it made.

Concorde was able to break the sound barrier during its flights and was therefore able to cause a sonic boom. Sonic booms were a problem in North Cornwall and North Devon as these areas were underneath the flight path of Concorde. Windows would rattle and in some cases the “torching” (pointing underneath roof slates) would be dislodged with the vibration. It was proposed that Concorde, before it was decommissioned, could open up new flight paths to Australia. However the plans were scrapped due to the fact that few other countries would allow Concorde to fly at supersonic speeds due to sonic booms being disruptive and potentially damaging.

But Charlie Stross’ article is an excellent counter-blast to the hype that we would ever want to travel sub-orbitally or hypersonically. It really is hard science fiction and we’ve been sold it since the space age.


Interstellar: A hard SF film that makes no sense

I hadn’t been to the movies in a while, but Christopher Nolan’s Interstellar was hyped up to be the best hard SF film since 2001: A Space Odyssey (and that film was religious philosophy in disguise to boot).

But the story makes no sense. The science makes no sense. Although the film makes generous use of Einstein’s special and general theories of relativity, what comes out makes no scientific sense.

I’m not the first to point out some of the things that are wrong with the science in Interstellar. Here’s some comments from Scientific American via Salon:

[Interstellar] paradoxically presents interstellar travel as both ridiculously easy yet impossibly hard.

This paradox stems from the film’s central plot device: a wormhole, a tunnel through spacetime that, if traversed, could allow for essentially instantaneous travel between far-distant points. Albert Einstein and his collaborator Nathan Rosen first popularized the idea in 1935, but wormholes have since found their greatest exposure in science fiction, since they in theory offer a way to shuttle fragile, corporeal characters around the cosmos at superluminal speeds. Place one end at, say, Saturn’s orbit, and another in the heart of the Andromeda Galaxy, and a chisel-cheeked hero like Matthew McConaughey can make an intergalactic crossing in a few moments that takes light itself—the fastest thing there is—a round trip of more than 5 million years. That’s the easy, appealing, compelling part.

The hard part is that outside of decidedly speculative equations there is no evidence whatsoever that wormholes actually exist, let alone that we could ever manipulate or traverse them if they did. Based on the theoretical work of Thorne and others, making a wormhole stable enough to use would require the existence and manipulation of another entirely hypothetical thing for which we have very little actual evidence: “exotic” matter—that is, matter that possesses negative mass and energy. So, to get to the stars, all we have to do is just rely on not one but two distinct entities, both of which we do not know how to create or manipulate and which in fact may be only mathematical mirages, like the impossible staircases in an M. C. Escher lithograph. All other schemes for faster-than-light travel—warp drives, hyperspace jumps, and the like—also have similar reality-challenging requirements.

Suffice to say that the task of traveling faster than light is in all likelihood even harder than making an interstellar voyage within the firm constraints of well-understood physical laws. If you put your faith in wormholes and warp drives to take us to the stars, you might as well rely on the intercessions of gods, ghosts, and demons as well—they’ll probably help just as much, which is not at all. Wormholes and other faster-than-light travel schemes won’t take us to the stars anytime soon, if ever.

That isn’t the biggest problem for me. The greatest problem is that on the greatest canvas of all – the Universe and the laws of astrophysics, the message is trivially and cloyingly naïve: the love of between a father and his daughter transcends everything including the gravity of supermassive black holes, wormholes and even the simultaneity paradox.

It’s not that I didn’t care about the characters. It’s that the story has more holes than a hyperdimensional sieve – meaning that I lost belief in the human predicament of the characters.

There are articles pointing out a few plot holes including an article in “The Business Insider” which points out three, as well as astrophysicist Neil deGrasse Tyson on Twitter who points out quite a few more.

And then there’s Bad Astronomer Phil Plait who gives it the full treatment. For example:

Cooper [played by Mat McConaughey] successfully pilots the ship through the wormhole (which was lovely and quite well-done, even down to the much-used explanation of how wormholes work borrowed from A Wrinkle in Time), and on the other side he and his crew find the three-planet system, which is inexplicably orbiting a black hole. I sighed audibly at this part. Where do the planets get heat and light? You kinda need a star for that. Heat couldn’t be from the black hole itself, because later (inevitably) Cooper has to go inside the black hole, and he doesn’t get fried. So the planets inexplicably are habitable despite no nearby source of warmth.

I sighed audibly at this part. Where do the planets get heat and light? You kinda need astar for that.

The Planet That Wasn’t There

It turns out that one of the three planets orbits very close to the black hole, so close there will be severe relativistic effects. Relative to a distant observer, time slows down near a black hole (true), so one hour on the planet will equal seven years elapsing back on Earth. Right away, this is a big problem. To get that kind of time dilation (a factor of about 60,000), you need to be just over the surface of the black hole, and I mean just over the surface, practically skimming it. But because of the way black holes twist up space, the minimum stable orbit around a black hole must be at leastthree times the size of the black hole itself. Clocks would run a bit more slowly at that distance than for someone on Earth, but only by about 20 percent.


Also, there’s the problem of tides. One side of the planet is much closer to the black hole than the other side. Gravity changes with distance; the farther you are from the source, the weaker the gravity you feel. The change in the force of the black hole’s gravity across a planet’s diameter is very large, creating a tidal force that stretches the planet. That close to a black hole, the tidal force is huge, mind-(and planet-)bendingly huge. So huge, the planet would be torn to shreds, vaporized.

So if the planet doesn’t fall in, it’s crushed to literally vapor. Either way, there’s no planet.


The explorers go down and find it covered in water as well as suffering through periodic ginormous tidal waves sweeping around it. These are unexplained, and I assumed they were caused by tides from the black hole … but that doesn’t work either. That close to the black hole, this inexplicably unvaporized planet would be tidally locked, always showing one face toward the hole. There would be huge tidal bulges pointing toward and away from the hole, but they wouldn’t move relative to the surface of the planet. No waves.


OK, fine, let me give just one more: the ultimate black hole. For the climax of the movie, Cooper has to fall into it. We see a ring of material around the black hole, presumably the accretion disk: a flat, swirling disk of material that is about to fall into the hole. Because of the incredible forces involved, accretion disks are extremely hot, like millions of degrees hot. They are so brilliant, they can be seen millions of light-years away and blast out enough radiation to completely destroy any normal material.

Yet Cooper flies over one like he’s flying over Saturn’s rings (literally; it was a visual callback to an earlier scene in the movie when they actually fly past Saturn’s rings). In reality, his ship would be flash-heated to a bazillion degrees and he would be nothing more than a thin and very flat stream of subatomic particles. All right all right all right?

Also, for some reason, we don’t see the accretion disk moving; it’s static, frozen, when in reality it would be whirling madly around the black hole. And, due to the tides I mentioned earlier, as Cooper fell in he would’ve been torn apart.

I don’t know about you but the hull of the spaceship (whose constituent parts can inexplicably land and take-off multiple times from alien planets but need an enormous chemically fired, multi-stage rocket to get to orbit from Earth) was clearly made of unobtanium.

But this is a film which heavily used ideas on black holes by theoretical physicist Kip Thorne, but I found myself thinking other heretical thoughts:

  • Are wormholes so massless that they can appear near Saturn and not have any measurable effect on the planet, its rings or it’s numerous moons?
  • The film’s central paradox is that the black hole/wormhole construction was revealed in the film to be caused by future humans – so where did they get the technology to do this from? Other future humans? It’s worse than the chicken-and-egg paradox, isn’t it?
  • How did a black hole and up having three Earth-like planets in the habitable zone? Does a black hole have a habitable zone?
  • If the character Cooper falls into a black hole, won’t he take an infinite amount of time as seen by Brand [Ann Hathaway] to cross the event horizon? I know that sometimes people can wait for love, but not literally forever.

The name of the black hole, Gargantua, is clearly from Kip Thorne’s book “Black Holes and Time Warps: Einstein’s outrageous legacy”, where the supermassive black hole that Thorne discusses is also called Gargantua (weighing in at 15 trillion  solar masses).

But then I formed an even more heretical thought:

  • What if black holes don’t exist?

I mean, although compact massive objects (much more massive than any neutron star) have definitely been described (including one at the centre of our own Milky Way galaxy), none of the other predictions of black hole theory have ever been observed – an event horizon, or the effects of the extreme frame-dragging of spacetime by a rotating black hole, for example.

I find myself looking at Schwarzschild’s solution for a spherically symmetric mass

{d \tau}^{2}=\left(1 - \frac{2M}{r} \right) dt^2 - \left(1-\frac{2M}{r}\right)^{-1} dr^2 - r^2 \left(d\theta^2 + \sin^2\theta \, d\varphi^2\right)

and I wonder whether we’ve missed something…

Mars One: Target without a mission

marsonelogoVia Slashdot, a very long (for the Internet) article on Mars One, the Dutch-based marketing campaign that says its going to send people to Mars starting in 2025.

It’s one thing to get 200,000 people to apply for a one-way trip to a dead planet, but quite another to actually come up with a full mission plan of how exactly you get people to the surface of Mars and have them live the rest of their lives there.

The details of Mars One’s mission remain vague. [Norbert] Kraft [Mars One’s Chief Medical Officer] tells me that any technical questions have to be directed to Arno Wielders [Mars One CEO], who rebuffs requests for an interview, replying through the press office that he is too busy. Instead, I am directed to the website. On a page titled “The Technology,” it states very optimistically: “No new technology developments are required to establish a human settlement on Mars. Mars One has visited major aerospace companies around the world to discuss the requirements, budget, and timelines with their engineers and business developers. The current mission plan was composed on the basis of feedback received in these meetings.”

Pretty much every proposal I find on the FAQ, from the landing unit to the living unit to the astronauts’ suits, is currently theoretical. Which is somewhat putting the cart before the horse, only the cart is a pencil drawing of a toy wheelbarrow. Here’s what it says, for instance, about how they will actually get people there: “Mars One anticipates using SpaceX Falcon Heavy, an upgraded version of the Falcon 9, which is in use by SpaceX currently. The Falcon Heavy is slated to undergo test flights in 2014, granting ample time for fine-tuning prior to the Mars One missions.”

This summer, a SpaceX Falcon 9 rocket prototype broke apart over Texas after “an anomaly forced the destruction on the craft.” A month later NASA lost a Russian-built rocket on launch bound for resupply of the International Space Station, its fireball in the night sky over Wallops Flight Facility visible for miles around. Two weeks ago, Virgin Galactic’s SpaceshipTwo exploded during a test flight over the Mojave, killing one pilot and injuring another. It’s a fraught moment even for private space missions far less theoretical than Mars One.

Quite. Even missions to Low Earth Orbit (LEO) or even to the edge of space are fraught with high risk, but they are nothing compared to going to Mars.

There have been 43 unmanned missions to Mars so far. Twenty one have failed.

And here’s the kicker medical problem

The longest any person has spent in space was the 14 months cosmonaut Valeri Polyakov lived on the now-decommissioned Mir Space Station; another cosmonaut,Valentin Lebedev, spent 211 days in orbit in 1982, during which the elevated radiation levels resulted in his losing his eyesight to cataracts. The flight to Mars is projected to take between seven and nine months.

So we’d have blind or nearly blind people on the surface of Mars? Terrific. Do we send guide dogs?

And there’s so much to look forward to.

Sleep patterns are badly disturbed by space travel, and more than half of astronauts on long-haul missions take sedatives to help them sleep. Fatigue and lethargy result in impaired cognitive functions and an increase in critical errors, which is why astronauts only have 6.5 “fit” work hours per day.

A lack of energy can be exacerbated by the limited diet astronauts must subsist on. Once their initial supplies ran out, Mars colonists would eat only food they could grow themselves, a plant-based diet, augmented by legumes and maybe insects.

I don’t know about you, but if I were to expect to be eating like that for the rest of my life, perhaps I should be eating like that now, just to see if I can stomach it or even survive on it?

Depression, anxiety, listlessness, hallucinations, and chronic stress have all been reported in live missions and training simulations. As have communication breakdowns and conflict among crews and between mission command.

And these breakdowns have been between military personnel who know they will be returning to Earth to face authority. What of the one-way Mars colonists? How long before they work out that there is no-one to stop one person killing all of the others? Or a multiple murder-suicide?

A well-known effect on astronauts out on long missions is the dip at the halfway point, when the excitement has worn off and the return home seems unbearably distant. There is no way to know how a human mind will encounter passing the threshold of no return, when the Earth recedes from sight, and the pitch black enormity of deep space and the impossibility of ever turning back sinks in.

I suspect that the excitement will abate by Day 3, after the transfer orbit burn. Watching the Earth move away perceptably day-by-day and communications with Earth get delayed more and more by the distance and the immutable speed of light will have a big effect on the crew.

Advice to Mars One: pack a lot of tranquilizers and anti-psychotic medications. This is going to be a long trip.

Eventually the four Mars One colonists will arrive on an inhospitable alien world, with only themselves for company for two years, until another flight with four colonists is hoped to arrive if they, too, survive the perilous trip through the vacuum of space. They will never speak to anyone but one another in real time ever again; the delay in relaying communications between Mars and Earth is 20 minutes, minimum.

But that assumes we can get them to the surface alive.

Apart from the ability to launch them to LEO safely, and then send them on a Hohmann transfer orbit safely (a task that the author of “The Martian” got spectacularly wrong – more on that in a later post), there is the key unanswered question of how to get human beings, not robots, to the surface of Mars without killing them.

The article glosses over that part, but in the scheme of things, getting humans from Mars Orbit to the surface is about the hardest engineering task ever considered.

Chris Hadfield, a Canadian astronaut who went to LEO says this (and this blog completely agrees with him):

“Going to Mars is hard,” Hadfield adds.As John Young, one of the most accomplished astronauts in history, said, ‘Mars is a lot further away than almost everybody thinks. Both physically and in time.’”

Astronaut Chris Hadfield (Alexander Nemenov/AFP/Getty Images)

Hadfield says that Mars One fails at even the most basic starting point of any manned space mission: If there are no specifications for the craft that will carry the crew, if you don’t know the very dimensions of the capsule they will be traveling in, you can’t begin to select the people who will be living and working inside of it.

“I really counsel every single one of the people who is interested in Mars One, whenever they ask me about it, to start asking the hard questions now. I want to see the technical specifications of the vehicle that is orbiting Earth. I want to know: How does a space suit on Mars work? Show me how it is pressurized, and how it is cooled. What’s the glove design? None of that stuff can be bought off the rack. It does not exist. You can’t just go to SpaceMart and buy those things.”

But that is exactly what Mars One is claiming to be able to do. All of its requirements for travel and living on Mars, it claims, are already here – whatever others like MIT and NASA or astronauts like Hadfield may say.

Hadfield continues:

“Thirteen years ago we started living on the space station, so when we left Earth, we basically started colonizing space as a planet. And then the next steps out were the moon, asteroids, and then eventually Mars. We absolutely need to do it on the moon for a few generations, learn how to do all of those things — how do you completely recycle your water? How do you completely recycle your oxygen system? How do you protect yourselves from radiation? How do you not go crazy? How do you set up the politics of the place and the command structure, so that when we get it wrong we won’t all die? How do we figure all that out?

I think a permanent moon base would definitely be do-able as a multi-national partnership. The moon is no more than 2.6 seconds in light travel time away from the Earth, and takes no more than 3-4 days to reach, and has the advantage of lower gravity and doesn’t have the disadvantage of a thin atmosphere.

The moon has also barely been surveyed for minerals, meteor impacts and ancient vulcanism. It has caves and lava tubes to explore as well.

The longest single excursion to the moon’s surface was 7 hours and 37 minutes by Eugene Cernan and Harrison Schmidt in Apollo 17 back in 1972. And they were on the Moon’s surface for just over 3 (Earth) days. Just imagine what a few weeks or months would do to the study of lunar geology, as well as understanding how to put an extraterrestrial base together and keeping humans alive and functioning for months at a time?

Since a long-term Mars base would be underground (because of the radiation), why not learn about how to do that on the Moon? You’d need a lot of power (a nuclear reactor would do) and a lot of robotic digging equipment.

Here’s an idea: try sending a nuclear-powered submarine to the moon. That would be almost exactly what you’d need to do if you want people to live there long-term, or on Mars.

But Mars One is little more than an aspiration and a website. Read the whole article. It’s not got the money and even if it had the money, it has no clue how to send people into low earth orbit, let alone any further.

…that from everything I can find, Mars One doesn’t appear to be in any way qualified to carry off the biggest, most complex, most audacious, and most dangerous exploration mission in all of human history. That they don’t have the money to do it. That 200,000 people didn’t actually apply. That, with all the good faith one can muster, I wouldn’t classify it exactly as a scam—but that it seems to be, at best, an amazingly hubristic fantasy: an absolute faith in the free market, in technology, in the media, in money, to be able to somehow, magically, do what thousands of highly qualified people in government agencies have so far not yet been able to do over decades of diligently trying, making slow headway through individually hard-won breakthroughs, working in relative anonymity pursuing their life’s work.

That’s what I call hard science fiction.

Another flying car prototype from Aeromobil

For as long as there has been a car stuck in traffic, there has been a wish for the flying car. Most never get off the ground (literally as well as financially).

And they are all prototypes.

This one actually works. And its from a company called Aeromobil in Slovakia.


It’s 6 meters long, so not something that can be parked in a normal carpark. But it does fly.

My worry is that any sort of prang in traffic on the ground would be a total insurance writeoff. How would you unbend the tail section?

It is beautiful though…

Suborbital flights fall to earth with SpaceShipTwo

In the past two days we have seen the tragic loss of Virgin Galactic’s SpaceShipTwo and the beginnings of the realization that what SpaceShipTwo represents is hubris for the extremely wealthy.

SpaceShipTwo crash debris photo courtesy of The Register

In an article by Wired, called “Space Tourism isn’t worth dying for” we have acknowledgement that space travel is at the very limits of technology:

A brave test pilot is dead and another one critically injured—in the service of a millionaire boondoggle thrill ride.

To be clear: I like spaceships. A lot. I went to the first landing of the space shuttle post-Challenger disaster. I went to the Mojave for the first test flight of SpaceShipOne, nominally to cover it but really just to gaze in wonder. I root for SpaceX, and felt real disappointment at Orbital Sciences’ Antares disaster this week.

But in the wake of this tragedy out at Mojave—not even the first time a SpaceShipTwo test has killed someone—we’re going to hear a lot about exploration, about pioneers and frontiers. People are going to talk about Giant Leaps for Mankind and Boldly Going Where No One Has Gone Before. And we should call bullshit on that.

SpaceShipTwo—at least, the version that has the Virgin Galactic livery painted on its tail—is not a Federation starship. It’s not a vehicle for the exploration of frontiers. This would be true even if Virgin Galactic did more than barely brush up against the bottom of space. Virgin Galactic is building the world’s most expensive roller coaster, the aerospace version of Beluga caviar. It’s a thing for rich people to do: pay $250,000 to not feel the weight of the world.

People get rich; they spend money. Sometimes it’s vulgar, but it’s the system we all seem to accept. When it costs the lives of the workers building that system, we should stop accepting it.

That fourth paragraph is the truth – that Virgin Galactic’s suborbital space flights are literally a mega-expensive rollercoaster that goes nowhere but endangers lives for no purpose at all.

It doesn’t even go anywhere: you take off from New Mexico and land in New Mexico (when they are supposed to be doing this commercially)

Graphic courtesy of The Guardian Media Group

But then of course in the very same article we move from the sublime to the ridiculous with Elon Musk’s vision for SpaceX:

That’s why a space program designed to get humanity off our native planet makes sense—but only a specific kind. Eventually this planet is going to be unlivable, either because of something we humans do to it or something natural. Asteroids have wiped Earth clean before, and presumably they’ll do it again. It’d be good to not be here when it happens. Elon Musk has made that part of his explicit rationale for SpaceX, his rocket company. Going to space is wondrous, difficult, and a testament to the human spirit. It’s also utterly, cynically practical. That’s being a pioneer.

Now that’s what I call a statement of “hard science fiction” at its finest – a testament to the power of science fiction narratives to override any sense or scientific credibility. Especially when those grandiose schemes come from a billionaire with vaulting ambitions and lots of spare money.

Space travel with our current levels of technology is a continuous battle for survival in a Universe hostile to life in all its forms. And we simply don’t have the answers to a lot of key questions about survival without contact with the Earth’s biosphere.

Even if we get to Mars, as I’ve already pointed out, we would be trying to colonize a dead planet which has toxic soils, a thin unbreathable atmosphere and deadly solar radiation. A desperate battle for survival from the moment of takeoff and for the rest of those colonists’ lives and for what reason? What overriding purpose? Would anyone want to have children in such a place?

For those who still think big, why not study the experience of the Viking colonists of Greenland, who migrated in the 10th and 11th Century and then slowly died a horrible lingering decline of near starvation for perhaps 150 years. First the harbours were blocked as sea ice clogged them as the climate turned colder, then the crops failed as the growing season became ever shorter until eventually they ate their way through their remaining cattle until they had nothing left. There were no trees so they couldn’t build ships. They were cut off and forgotten by their originating cultures.

Only more recently, has the recent warming of the 20th Century revealed the frozen remains of what were once homes and stables. It’s still colder there than it was in the 11th Century.

Want to colonize Mars? Try colonizing  Greenland or Antarctica without help or hope of rescue. Then get back to me on what a wonderful experience it was.