Bad Astronomy
The entire universe in blog form

Oct. 10 2016 9:00 AM

Would You Vote for Someone Who Thinks the Earth Is Flat?

Think about this for a moment: Would you vote for someone running for Congress—or to be president of the United States—who thought the Earth was flat?

And I don’t mean someone who’s just flirting with the idea, but someone who really, truly believes the Earth is a flat disk floating in space. Someone who refuses to accept any and all scientific evidence to the contrary no matter how obvious, someone who is proud of his belief, who campaigns on it, who actually holds hearings about it, condemning scientists and even threatening their careers because those scientists say the Earth is round. What would such a person do with legislative power over, say, NASA?

Can you imagine yourself voting for him?

Now imagine casting your ballot for a climate change denier. Someone like Rep. Lamar Smith (R-Texas) —who currently is the chairman of the House Committee on Science, Space, and Technology— or Sen. James Inhofe (R-Oklahoma), Donald Trump, Mike Pence, or practically every single sitting Congress member with an R for their political affiliation (although there is hope some bipartisan work can be done).

At this point in our understanding, I see very little difference between denying climate change versus someone who thinks the Earth is flat, or that the Moon landings were faked. All these people deny the overwhelming evidence and substitute their own fevered imaginations and biases for reality.

There will always be people like that, of course. Denialism will never die. But that doesn’t mean we have to give them power over us.

Many climate scientists feel the same way. Michael Mann and Stefan Rahmstorf, for example,  were interviewed for a video by Earth101 called “How Dead Is Denial?”, and they cut right to the chase:

I agree with Dr. Mann; there will always be people who will deny reality even when they’re standing chained to the railroad tracks with a train 10 meters away and bearing down on them at full speed. Especially for those who receive a whole lot of funding to stick their fingers in their ears and yell “LALALALALALALA” at the top of their lungs.

And when it comes to climate change, we’re chained on the tracks with them. We’ve been trying for years to get them to take their fingers out of their ears and open their eyes, and it’s long past time to admit this isn’t working. They refuse no matter what we do.

We need to cut ourselves free of them, and replace them with people who understand that we need to step off this track.

Vote. For yourself, for everyone you know, for future generations: Vote. If we want to stop the train, the first thing we must do is elect politicians who at the very least understand that it’s real, and that the danger we face is very real as well.

Tip o’ the voting booth lever to Michael Mann.

Oct. 8 2016 9:00 AM

Deep Sky Colors: A Gorgeous Astrophotography Book

I don’t plug stuff much on the blog for a lot of reasons, but one is that I only want to endorse things I truly, actually like. If I just shill for a bunch of stuff there’s not much reason to trust me, but if I save it for the really special stuff, well then, you’ll know it’s special.

This is special.

Rogelio Bernal Andreo’s book, Deep Sky Colors, is a ridiculously stunning collection of his astrophotographs. Andreo’s work is simply phenomenal, and basically you should just go and buy both that book and his other, Hawai’i Nights, because your brain will love you for it. Both are available on his website. You can even grab a free PDF of Hawai'i Nights, too.

When he asked me to write the foreword for Deep Sky Colors, I didn’t even hesitate. It was an easy decision, and easy to write: His photos have had quite the effect on me.

With his permission, I am posting what I wrote for the foreword. I’ll leave you with it, and with this: The holidays are coming. Wouldn’t it be nice to have at least some of the shopping done this soon?

I remember when I first saw one of Rogelio Bernal Andreo’s photographs.
It was in 2010. I don’t remember how I found him; probably someone sent me a link to his work. I write a lot about the beauty and majesty of the skies, and love to feature the work of so-called “amateur” astronomers, many of whom have a dedication to the sky and the talent to photograph it unsurpassed by anyone.
Over the years, the hardest part of writing about these photos is simply picking them; there are so many accomplished astrophotographers out there, and it gets to the point where I only want to feature something unusual — an odd framing of a familiar object, some deep sky galaxy usually unseen, or a balance of filters and exposures not generally used.
So I probably “ho-hummed” to myself as I clicked the link to Rogelio’s mosaic of Orion; after all, who hasn’t seen a million photos of this constellation?
When his photo came up on my screen, I may have choked on my morning coffee. It’s magnificent. And truly unique, showing a depth and beauty I had literally never seen before; the nebulosity strewn across the constellation sharp and colorful, every color balanced, the stars spread like jewels on polychrome velvet.
It was, quite simply, the most beautiful astrophotograph I had ever seen. That’s why I chose it as the Number 1 photo of 2010 on my blog. It really is that amazing.
In the time since then Rogelio has been kind enough to let me use his photos on my blog and in educational videos as well. They’ve improved my own work hugely. It’s surprising to me that a good, deep photo of the Virgo Cluster of galaxies is difficult to find online. When we needed one for the Crash Course Astronomy video series I turned to Rogelio, and sure enough he had the exact, perfect shot for it. He graciously allowed us to use several more as well, and the series was the better for it.
The ridiculously beautiful book that follows these words is a showcase of Rogelio’s work, and is a powerful reminder of how much beauty exists in the world and above it. It takes a sharp eye and imaginative brain to be able to display it as he does, and we get to enjoy all his hard work.
If there is a match made in heaven — or in the heavens — it’s Rogelio and the night sky. The photos in this book will prove it.

Oct. 7 2016 9:00 AM

As Hurricane Matthew Hits Florida, What Will It Do to NASA?

Update, Oct. 9, 2016: As hoped, it looks like KSC got through Matthew with only relatively little damage. Eric Berger at Ars Technica has more details.

Update and correction, midnight: I've now heard the GOES-R satellite, mentioned below, was not mated to the rocket (note: that was my error, not of the sources below), and also that is in Titusville, across the Indian River and so technically not at the Cape, but instead a few kilometers away. We'll learn more once the all clear is given at KSC and people are allowed back.

Update, noon: I've heard from two sources that the GOES-R satellite is sitting inside an Atlas rocket at the Cape. It was protected by a hurricane enclosure, but I'm awaiting word it made it through OK. Ironically, it's a weather satellite.

Update at 11:30 a.m.: NASA is reporting that the hurricane center has passed north of Kennedy Space Center, and there is some damage but it's minimal. Phew! Here's the quote:

Hurricane Matthew has now passed offshore from Cape Canaveral and is north of Kennedy Space Center. The wind is starting to decline but remains near tropical storm strength. However, until the wind is consistently below 50 knots a crew cannot be sent outside to begin a more thorough look at KSC. That is expected sometime this afternoon. At this time there is observed to be limited roof damage to KSC facilities, water and electrical utilities services have been disrupted and there is scattered debris. Storm surge has been observed to be relatively minimal, limited to localized portions of the space center. The Damage Assessment and Recovery Team will be brought in for its formal assessment Saturday morning.

Original post, 9 a.m.: Hurricane Matthew is a monster. It went from a run of the mill tropical depression to a full blown hurricane in less than a day, strengthening explosively as it drew energy from deep, warm waters. It passed over Haiti, doing vast damage and killing more than 300 people, and now its sights are set on the east coast of Florida and points north.

I will not downplay this storm. With top wind speeds of more than 220 kph (140 mph) the damage it can do is not to be underestimated. Its path along the coast is guaranteed to do a lot of hurt.

Beside the obvious worries, I’ve seen a lot of questions and speculation on social media about what the hurricane might do to NASA’s Kennedy Space Center and launch facilities; while they aren’t on the direct path of the hurricane eye, it’ll pass close. As Eric Berger points out at Ars Technica, most of the buildings there are built to withstand hurricane winds of more than 160 kph, and some more. But Matthew has winds exceeding this, so it may very well damage the center.

The facility has been evacuated, with only a very thin skeleton crew on hand to ride it out. Mind you, several launch pads could be damaged as well. The working SpaceX pad was already damaged when a Falcon 9 rocket exploded while fueling in September. It’s unclear what the hurricane could add to it. I’ll note it’s safe to assume that all rockets and other equipment at the center have been secured.

As hard as it is, we’ll just have to wait and see what this thing does. Having lived through a few hurricanes, I’ll say it can be terrifying. I hope everyone reading this in that area stays safe and that our nation’s space assets are safe as well.

As an aside, I’ll note that this hurricane seems to have the fingerprints of global warming all over it. As climatologist Michael Mann notes the deeper layer of warm water fueling it is a product of extra warming going into the ocean, and there has been a trend of the most powerful recent storms getting stronger. I worry that as powerful as this hurricane is, we will probably see more like it in the coming years.

For more information, I recommend keeping an eye on Weather Underground, which is an excellent source of information. And again, folks: Be safe.

N.B. Before anyone accuses me of politicizing a tragedy, let me note that science is not in itself a political thing, but it certainly can be a pawn to it. Also note that it already has been politicized by the usual right-wing deniers like Matt Drudge and Rush Limbaugh, who, even for them, have stooped unusually low, including possibly putting lives at risk. My main concern now is with the immediate threat and the safety of people, property, and ecosystems; there will be time later to go into more depth about the causes of this storm.

Oct. 6 2016 9:00 AM

Blue Origin Tests Its Rocket Escape System in a VERY Dramatic Way

On Wednesday, Blue Origin had a helluva day.

After a handful of short holds, the company’s New Shepard rocket lifted off for the fifth time from the Texas desert proving grounds, heading up into space. Like the previous four test flights, this was to be a short suborbital hop: Straight up, pass the 100 kilometer line that demarcates the arbitrary but agreed-upon border of space, then back down to land vertically again.

But even for this rocket, this was no ordinary flight.

As I wrote earlier in September, this test flight had pretty good odds of being the last time we’d see this five-time booster intact. The reason was that the crew capsule’s emergency abort rocket was to be tested in flight. Roughly 45 seconds in, when New Shepard was undergoing maximum pressure as it rammed through Earth’s atmosphere, the powerful rocket motors along the bottom of the crew capsule would ignite, blasting it away from the booster underneath. This abort system is set up in case there’s a problem during the flight, and the crew needs to get away fast.

It was expected that this escape procedure might destroy the booster, kicking it sideways or otherwise putting huge stress on it. Full of fuel and off-balance, it might have exploded or fallen to the ground to explode there.

Instead, everything went pretty much perfectly. And it’s still incredibly dramatic! Watch (start at the 51:18 mark):

Holy wow! At T+45 seconds, the rockets kick in and the crew capsule roars away. Amazingly, the booster hardly even notices; it just keeps on thrusting up, up, and away. The crew capsule had a bit of a wild ride, oscillating almost upside down at one point after the rockets under it quit, but soon enough the drogue ’chutes popped out and it stabilized, and then the main ’chutes opened to give it a smooth ride down to the ground.

Then, amazingly, the booster comes back and lands on its tail like it was no big deal at all! That was stunning to watch.

Moments after separation the capsule blasted away from the booster below on a tail of fire.

Blue Origin

It’s hard to overemphasize how important this was. For one thing, no other rocket on Earth has been launched into space and landed on its tail five times like this one. For another, there hasn’t been an emergency escape sequence like this tested since the Apollo days in the 1960s! For a third, this shows that Blue Origin can have an emergency escape and retrieve both parts of the rocket safely.

Altogether, that’s a pretty big deal. Blue Origin just showed the world that it can make big plans and execute them. I’ll note that until very recently they were very secretive about their work and even their launches, not releasing information until after the tests were done. Their holding live webcasts now shows just how confident they are on their path.

And their path is big. I wrote about Elon Musk and SpaceX’s plans to go to Mars just last week. But not long before that, Jeff Bezos released Blue Origin’s plans to build much bigger rockets. Their New Glenn rocket will be quite capable of achieving orbit. Note the names of the rockets: Alan Shepard was the first American in space, on a suborbital flight. John Glenn was the first American to orbit the Earth.

Bezos also said the next line of rockets after New Glenn will be the New Armstrong. I wonder what his plans are for that …?

Update, Oct. 6, 2016 at 17:30 UTC: Blue Origin CEO Jeff Bezos just tweeted about new footage showing the emergency escape in very slow motion. It's pretty cool; especially the booster emerging from the rocket plume steady as a rock:

Blue Origin is creating a new rocket engine, the BE-4, which is very powerful. Seven of these will power New Glenn, which will make it a rival of SpaceX's Falcon Heavy. Both companies have plans for bigger and more powerful rockets yet. Both have their sights set on getting out of Earth orbit, and into interplanetary space.

I’ve said this before, and I’ll say it again now: People say it’s a curse to live in exciting times. Those people are wrong.

Congratulations to the folks at Blue Origin! As you say: Gradatim Ferociter!

Oct. 5 2016 9:00 AM

Arctic Ice Reaches Second Lowest Extent on Record

Some records are best not broken. Especially when it’s the record for least amount of Arctic ice remaining after a summer of melting.

So it’s good that 2016 did not break that record. But when you look more carefully, you’ll find that’s hardly a relief.

The Earth’s boreal ice cap melts every summer as our planet’s North Pole tips toward the Sun in spring. The days get longer, the Sun gets higher, and the increased warmth melts the ice. This is a natural cycle and has been going on for a long time. In general, September of every year is when the ice reaches lowest amount.

This year, 2016, the ice reached its lowest extent* on Sept. 10. On that day, it had an extent of 4.14 million square kilometers, or about half the area of the contiguous United States. That’s very low. So low, in fact that it’s the second lowest extent ever measured, in a dead tie with 2007.

The all-time record low measured extent was in 2012, which was 3.41 million square km. But there are a couple of important things to note here.

One is that 2012 was very unusual. A dam made of ice in northern Canada broke, allowing warm water to mix with the Arctic ice, melting the ice far more than usual. That, at least in part, is what led to the record low extent of that year.

2016 had no such anomaly that is known. In other words, we just hit the second lowest amount of ice ever seen, and nothing unusual caused it.

Well, unless you don’t count fierce global warming as unusual. Sadly, it is the new normal.

sea ice extent graph
A plot of sea ice extent over time. The red line is 2016, and the dashed blue line is 2012. The black line is the average extent from 1981–2010, and the shaded gray area is two standard deviations from average—anything outside of this range is more likely to be statistically significant.


The other thing to note is that all these records have occurred very recently. That too is because our planet is heating up. Every year we get just a bit hotter, and more records fall (in fact, as you’d expect, far more high temperature records are broken than lows). The record in 2012 has stood because it was caused by global warming plus more rare events like the ice dam breaking. But every year we get a bit hotter, and soon we won’t need those unusual events to break 2012’s record.

So I don’t expect 2012 to hold on to its status much longer. Arctic ice is in a death spiral, and it won’t be long (even on a human timescale) before we get an ice-free summer. Most predictions put that event in the mid-2040s. Even now, enough ice melts every summer to allow ships to ply the Northwest Passage.

Mind you, the Arctic still did break a record this year: It had the lowest maximum extent back in March. Every year in winter the water freezes, reaching its maximum area in early spring. When you compare the area at maximum extent over the years, that’s dropping too.

Not only that, but as Tamino points out at the blog Open Mind, 2016 is on its way to having the lowest average annual extent ever measured as well. Having the smallest maximum and near-record minimum makes that one pretty easy to understand.

This is all important because the difference in temperature between the poles and the equator drives much of Earth’s weather patterns. Warm water from the equator flows toward the poles, cools, sinks down into the oceans, then flows back to the equator to start the cycle again. This conveyor belt of heat is thought to help power the jet stream. As the poles warm, the difference in temperature across the latitudes shrinks. This weakens the jet stream, letting cold air from the Arctic drop down, bringing those “polar vortices” and their frigid temperatures into the U.S.

So yes, you can get colder weather with more global warming. An ice-free Arctic means a lot more than just easy passage across the northern Canadian ocean. It means a destabilization of the delicate balance of our water, atmosphere, and land, disrupting everything.

As I now point out every time I write an article like this, not all is lost. But we cannot do anything until we get politicians to at the very least recognize the danger we are in. Too many do not, flatly denying the science acknowledged and understood by the vast majority of climatologists.

The first step we need to take is vote those people out. Your voice matters. Vote.

*“Extent” is technical term that is more or less equal to the area covered by ice; scientists divide the Arctic into bins, and a given bin is said to have ice if more than 15 percent of it is frozen.

Oct. 4 2016 9:00 AM

How Big Can a Black Hole Get?

Black holes are everywhere in the Universe. A typical galaxy might have millions of stellar-mass black holes, ones created when a massive star explodes (this is usually the kind you think of when you think “black hole”).

But some black holes are true monsters, with millions or even billions of times the Sun’s mass. We think that every large galaxy has one of these supermassive black holes in its core. Study after study has shown that these black holes have a symbiotic relationship with their host galaxies, too, growing along with them as each formed billions of years ago.

We know galaxies can get pretty big. It has to make you wonder: How big can these black holes get?

It’s a good question, and surprisingly hard to answer. Although there are a number of ways to “weigh” a black hole (really, measure its mass), but given the sheer number of galaxies out there these methods can be hard to implement on a large scale (I almost wrote “mass produced basis” but figured that’s pushing the pun too much). Despite that, we've found a few really big ones, and that can help us figure out what the upper limit to their size might be.

Now mind you, theoretically there isn’t an upper limit to them. You could, if you had godlike powers, collect every single bit of matter in the Universe, cram it into one spot, and have a truly and literally cosmic black hole with a sextillion times the Sun’s mass. More or less.

But realistically, that’s not possible. Matter is distributed throughout the Universe in the form of stars, gas, dark matter, and so on. The biggest black holes that actually exist today would probably need to be born big, and then grow over time. So the more practical question is, what’s the biggest black hole practically possible right now?

Some astronomers looked into this, and found what may be the answer: The most massive black holes likely to exist in the Universe today are about 10 billion times the mass of the Sun.

That’s still pretty dang massive. The supermassive black hole in the center of the Milky Way, our home galaxy, is around 4 million solar masses, so these monsters (called ultramassive black holes, or UMBHs) could be more than 2,000 times more massive!

How can such beasts exist?

dark matter
In the early Universe, dark matter collected along huge filaments hundreds of milions of light-years long, as depicted in this astrophysical simulation.

Masaki et al.

To answer that, the astronomers looked at how black holes form in the first place, and how they could grow. In the early Universe, when it was less than a billion or so years old, things were different. Galaxies were in their earliest stages of formation, and the Universe was mostly gas and dark matter. The dark matter was distributed along huge filaments, and its gravity pulled normal matter toward it. These were the early structures, the scaffolding, upon which galaxies would form.

… and big black holes, too. Under these conditions, there are two ways supermassive black holes could’ve formed. The first is that the gas collected into huge stars, far larger than can exist today, with more than 100 or possibly even 1,000 times the mass of the Sun. These stars can’t exist today; the presence of heavy elements makes the stars too hot, and anything more than 100 or so times the Sun’s mass gets so energetic it would tear itself apart. But in the early Universe those heavy elements weren’t created yet (they form inside massive stars, as it happens), and all that was around was hydrogen, helium, and a smidgen of lithium. These primordial stars would’ve lived very short lives, blown up, and then formed huge black holes when their cores collapsed. Over time, these first black holes would draw in matter around then, growing huge.

The second way huge early black holes could form was using dark matter as a funnel. Those huge filaments of dark matter would channel normal matter down into tight knots of material. The flow could’ve been so fast that there simply wasn’t time to form a star first; instead the matter collapsed directly into a black hole. In this sense, the black holes were formed from “seeds”; a black hole was born and then grew rapidly.

Both scenarios—stars and seeds—are physically possible, and can produce a black hole with a billion times the Sun’s mass in a billion years after the Big Bang.

binary black holes
Artwork depicting two giant black holes orbiting each other, on a slow death spiral that will end in their merging into one bigger black hole.

P. Marenfeld and NOAO/AURA/NSF.

But that’s just the start. To get as big as we see them today, they have to grow. They can do that by simply eating more material (the dark matter that fed them initially can help there). But remember, not long after they were born these black holes had galaxies growing around them. Given longer timescales, galaxies can collide and merge. When they do, the black holes in their centers can merge as well. In clusters of galaxies, there can be thousands of galaxies all bound together by their gravity. Given reasonable growth rates, the theoretical models predict black holes can grow to 10 billion times the mass of the Sun over the age of the Universe.

And that’s how we could get ultramassive black holes today. Still, that’s theory. What about observations?

To check these numbers, the astronomers in the new study compared what they expect to see today versus what’s actually observed in galaxies. How do you measure a black hole? Indirectly: As black holes feed on matter, the material forms a swirling disk around it. This gets very hot, and glows. If the temperature reaches millions of degrees (which, terrifyingly, it can and does) it will emit X-rays, and those can be seen out to huge distances.

We see lots of these “active galaxies” in the early Universe, and they were pouring out X-rays, meaning their central black holes were feeding voraciously. During that time they were very efficient at gaining mass, and could grow huge. But how huge? And how many huge ones do we expect to see today?

There have been surveys of black holes in galaxies taken, and, for example, one of them found a handful of UMBHs out of the thousands of galaxies they looked at. It turns out that’s a problem: Assuming that brighter galaxies means more big black holes, the astronomers doing the new study predicted there should be thousands.

Obviously, something was wrong. They think that their assumption that you can simply extrapolate brightness to black hole growth doesn’t work on the high end. One explanation is that we know black holes are sloppy eaters. The tremendous amount of light the disk emits can blow a vast wind of particles outward, and that can choke off the flow of matter inward. If black holes try to eat too fast, their food dries up!

When they accounted for that, the astronomers found their numbers aligning better with observations. Interestingly, those observations indicate that the most massive black holes we see today really are about 10 billion solar masses, about what the models predicted.

How many of them do we see? Running the numbers, they predict there should be one UMBH in a volume of space encompassing 3x1026 cubic light years: a cube about 700 million light-years across one side.

That’s a ridiculously staggeringly huge volume of space, which means there aren’t too many of these monsters. There are roughly a million galaxies within this distance of us, and odds are only one has a UMBH in it.

Still, we should see a few of these monsters if we probe the Universe more deeply. That work is being done now, looking at the biggest and brightest galaxies we can, and no doubt will continue for a long time. Investigating the biggest black holes in the cosmos is enduring work. There are a lot of them to find, and they’re probably really far away.

And it’s important work, too. If the Universe limits the sizes of things, then there’s a reason for it. Maybe there wasn’t time for black holes to grow any bigger. Maybe their overall growth rate is limited. Maybe bigger ones exist and they’re so rare we haven’t seen them yet.

All of these facts tell us about the conditions in the early Universe, and how it’s changed since then to today. And all of that plays its role in the bigger picture of science itself: trying to understand how we got here, and why the Universe is the way it is. I find it positively enthralling that we can ponder and attempt to solve such problems.

And being able to think of the biggest black holes in the Universe as puzzle pieces in this bigger picture is pretty cool, too.

Oh, one final note: These UMBHs are the size they are now because the Universe is only about 14 billion years old. But time goes on, and over the next few trillion, quadrillion, and octillion years—even more—eventually these black holes will consume most everything in their galaxies, and grow huger still. They’ll outlast the stars, and possibly even matter itself! In a future so distant the numbers are almost meaningless, they will be the only large objects in the entire cosmos … and even they will eventually die. I talk about this in Crash Course Astronomy: Deep Time. If there’s a life lesson in there, feel free to ponder it.

Tip o’ the accretion disk to Randall Munroe, who mentioned this study in a What if? comic about, of all things, fireflies.

Oct. 3 2016 9:00 AM

Goodnight, Rosetta

On Friday, the Rosetta mission came to a close. At 11:19 UTC, the radio signal received at Earth from the spacecraft was cut off when the orbiter became a lander, slowly impacting and coming to rest on the surface of a comet.

At that moment, it became more than it once was; it became a part of the comet it had been chasing since it was launched on March 2, 2004.

It was August 2014 when Rosetta first approached and made rendezvous with 67P/Churyumov-Gerasimenko, a chunk of ice and rock and gravel and dust orbiting the Sun every 6½. The wonders of the comet had already been streaming in; even from a distance Rosetta found it not to be a single monolithic object, but two distinct lobes connected by a narrow neck.

Cliffs and rocks seen by Rosetta on its way down, still 16 kilometers above the surface.


But the discoveries came crashing in. The comet had no impact sites, none. The surface must be incredibly young, or else it would have accumulated impact craters over the eons. While expected—comets were known to have volatile surfaces that change over short time periods, even by human standards—the surface was still odd and magnificent, like sculpted half-frozen whipped cream.

Active pits were seen where water ice, heated by the Sun, turned into a gas and blew away. Aeolian features were also photographed, shapes carved and sculpted by the whisper of gas escaping from the comet’s interior. Smooth regions were found where finer grains of material flowed down in the comet’s gravity, despite its pull being so weak you could launch yourself into interplanetary space with a single good jump.

One of my favorite mysteries—why so many objects like asteroids and comets are not single objects but instead double-lobed—may have finally been solved using Rosetta’s observations. The pieces collided slowly, sticking together. Over time, sunlight causes the comet to rotate more rapidly until the pieces fly apart, but their gravity draws them together again, starting the process all over once more. It’s a poetic and lovely dance that may be common in small bodies.

landing sequence
A sequence of images Rosetta took as it approached the comet showing its landing site.


And then there was Philae, the plucky, anthropomorphized lander that failed in its primary mission to land on a comet safely, but still managed to squeak out some science even after bouncing several times on the surface and landing sideways wedged up against a towering rock face. It managed to send back some data despite its predicament, and we learned yet even more about the comet. Where it landed exactly was unknown until just a few weeks ago, when high-resolution images finally were able to show its last resting place.

And now Rosetta has come to join it. The decision to land the orbiter on the comet is not an easy one, but it makes sense. The funding used to run it can be used for other missions, and its success had already led to it being given a lengthy mission extension. Moreover, the comet orbits the Sun on an ellipse, and it’s well away from us now, the signal weaker. Also, from its view the Sun and Earth would be close together in the sky, making communicating with it difficult for many weeks at a time.

There comes a time in every mission when it must be ended, and we move on to what’s next. It can be bittersweet, and this is no exception. Rosetta was a triumph, blazing new ground and overcoming adversity to succeed. It’s a monument to what we can do when we work together and really try.

As a tribute to that, the folks at ESA made this lovely animation to celebrate the last moments of the mission:

Make sure you watch it to the very end; it doesn’t stop when you first think it does.

… and if you’re wondering what the reference there is at the very end, it’s referring to this phenomenal, wondrous video: “Ambition.”

This is the true legacy of Rosetta, the first mission to dare land on a comet and follow it around the Sun. The science it returned was why we sent it. But the inspiration it instills in us will stir generations of explorers to come.

Per inspiratione, ad astra.

For more about Rosetta, Philae, sand 67P, here are some articles I wrote over the years:

Oct. 1 2016 9:00 AM

Chairman of Illusions

Richard Wiseman is a psychologist and master of illusion. He delights in fooling your sense of perspective, memory, and overall perception. And he’s at it again, creating a lovely variation on a classic Beuchet chair illusion.

Some people say that Richard Wiseman and I look a lot alike. I’ll admit I occasionally refer to him as my evil twin, but then again sometimes I really don’t see it. After all, I’m apparently much, much taller than he is.

Richard Wiseman chair illusion
He's a man outstanding in his chair.

Richard Wiseman

This sort of forced perspective is fun to read about. It’s a variation of the Ames room, a specially designed distorted room that is set up in a way to look normal but distorting objects in it. A lot of “Mystery Spot” type tourist traps use it.

I wrote about another variation of this sort of thing a while back, for a video that tricks you in more ways than one:

It’s so easy to fool our brains! Remember, what you see is not always what you get. And when you hear someone making an extraordinary claim, saying, “I know what I saw!” you can bet they really don’t.

Sept. 30 2016 9:00 AM

Sentinel-1A Satellite Slammed by Space Debris

Space debris is a growing problem. Space is big—as many of us like to say, that’s why we call it “space”—but over time collisions are inevitable. This can have catastrophic consequences, including the loss of a satellite … and if the collision is violent enough it can create even more debris, increasing the hazard over time.*

Large collisions are very rare, because big objects are few. But there are vastly more smaller objects in space than big ones, making smaller collisions more common. In fact, on Aug. 23, the European Space Agency satellite Sentinel-1A suffered an impact from a small object, probably just a few millimeters across, which slammed into one of its solar panels and left a visible dent nearly a half meter across.

The impact was noticed immediately by ground controllers; the amount of electricity from the panels getting to the spacecraft dropped by a few percent, the orientation of the spacecraft suddenly shifted, and the orbit changed a slight amount as well. An impact was suspected, and images taken by onboard cameras quickly confirmed the collision.

The damage is minimal, so the spacecraft is fine (the amount of power loss is small, onboard attitude control fixed the orientation, and the orbit is adjusted every week anyway). It’s no surprise the solar panel was hit, because they are the largest component of the spacecraft and present the biggest target. Had the main spacecraft been hit, though, it could have resulted in serious damage.

before and after
Before and after shot shows the damage to the panel.


One thing that’s not clear is if the impactor was actual space debris (that is, human-made debris from another spacecraft) or a micrometeorite from deep space. Micrometeorites travel much more rapidly (more than 20 km/s versus perhaps 12 for space debris), so a smaller bit can make a bigger hole. According to the telemetry and the images, the impactor came in from the direction the spacecraft is moving. That strongly implies it was space debris in a similar polar orbit to Sentinel-1A; micrometeorites can come in from any direction and so an alignment with the satellite’s orbit would be highly unlikely.

I’ll note that space debris larger than a few centimeters across is tracked from the ground, but something the size of a grain of sand or a small pebble is far too small to be detected. That makes them very dangerous, but it’s not clear what can be done about them. There are plans to clean up larger debris, but smaller debris remains an issue.

It’s interesting that images were taken of the damage. Sentinel-1A is equipped with cameras, but they were only used to observe the solar panels unfolding after the satellite was first launched, and then they were turned off. They were turned back on after the impact to see if any damage was visible. It wouldn’t surprise me if more satellites were equipped this way in the future. There have been many cases where debris collisions have been suspected to cause satellite anomalies, but without pictures it’s hard to be sure.

The good news is that Sentinel-1A is OK. In fact the very next day after the collision it was used to survey Italy from space after a massive earthquake struck that country, and the observations are helping scientists understand the ground movement after the event.

Engineers and space scientists take the problem of debris collisions seriously, though it may be a while before real solutions are evident. Until then, the best we can do is hope our birds don’t get hit. I’m just glad Sentinel-1A survived its encounter.

*See the documentary Gravity, Bullock, S. and Clooney., G, 2013

Sept. 29 2016 9:05 AM

Elon Musk Wants to Put a Million People on Mars

It’s no secret that Elon Musk wants to go to Mars. This week, he showed how he—and a lot more people—just might do it.

At the International Astronautical Congress in Mexico on Tuesday—and after teasing it for many months—he finally revealed his vision for the future of SpaceX, and possibly humanity.* It involves a big rocket, a big spaceship, a big fleet, and big money.

Perhaps you sense a theme here. Bigness.

He calls it the Interplanetary Transport System, or ITS, and he’s not thinking small: He claims this plan can lead to a city on Mars of 1 million people or more, and it could be well on its way in less than a century. It’ll take thousands upon thousands of individual rocket flights.

What he and his company are planning is not in any way easy, and as he himself pointed out with characteristic understatement in a press conference after the announcement, “A lot of things have to go right.”

Yes indeed. So what exactly has to go right to put humanity on the Red Planet?

The Hardware

The plan is to use an enormous rocket, comfortably larger than the Saturn V that sent humans to the Moon, topped with a spaceship that can hold as many as 100 people. It will go to orbit, be refueled using multiple launches, blast its way to Mars, enter the atmosphere using aerodynamic braking to slow, then eventually land on its tail.

SpaceX put together a pretty dramatic animation of the basic flight:

Watching that I felt like I was seeing an updated version of movies I used to watch as a kid. But having thought it over, I have to say that what Musk is planning is doable. Yes, seriously. The engineering challenge is formidable, but technically possible.

There are four critical engineering steps needed to make all this a reality: The rocket must be fully reusable, the spaceship (the section that will actually go to Mars with people and supplies) must be refilled with fuel and oxygen on orbit, the right propellant must be used, and there must be a means of making that propellant on Mars itself.

None of these is easy. Not by a long shot. But they are possible.

comparing ITS to Saturn V
Comparing the ITS to the Saturn V. Yeah, it's big.


First, the rocket. The as-yet unnamed booster is beefy. It’ll be 122 meters tall and about 12 meters wide (the Saturn V was 111 x 10 meters in size). That’s big. But it’s the thrust that shocked me: It’s planned to have a staggering 13,000 tons (29 million pounds) of thrust. The Saturn V—still to this day the most powerful rocket ever launched—had a thrust of 3,500 tons (7.5 million pounds). The SpaceX booster will have a thrust 3.5 times as much as that.

Thrust is one way to characterize how much stuff you can throw into space. This booster will be able to throw a lot. It should lift about 500 tons into Earth orbit, which is a huge payload. The heaviest payload the Space Shuttle took to orbit, the Chandra Observatory, had a mass of about five tons.*

That huge thrust is good, because the Mars spaceship will be huge, too. Measuring about 50 meters long and 19 meters wide, it’ll be so heavy that even the enormous booster won’t be able to put it into orbit by itself. After the booster drops away, the spaceship (again, also as-yet unnamed) will use its own engines to get the rest of the way to orbit, using most of its fuel doing so.

Artwork of the ITS spaceship refueling with a tanker in orbit.


That means the spaceship will have to be refueled. Or, as Musk put it, “refilled”; it’ll need fuel and oxygen used to burn the fuel. That’ll need more rocket launches, which in turn means the booster must be reusable. Like the Falcon 9 first stage, which has now been successfully relanded a half-dozen times; after boosting the spaceship as fast and high as it can, the giant rocket will turn around, slow, descend, and then land itself back at Cape Canaveral in Florida. Musk notes that they’re getting pretty good at this with the Falcon 9, and each landing is more accurate.

The ITS booster could be back on the pad after as little as 20 minutes. It’ll be inspected, and if it’s good to go a tanker full of fuel and oxidizer will be mated to it. The tanker is basically the same design as the spaceship itself (redundant designs save a lot of money and time to develop). It’ll launch into orbit, meet up with the spaceship, mate, and transfer the fuel. This may have to be done several times to give the ship enough fuel to get to Mars.

Once that’s all done, the spaceship leaves Earth orbit, accelerates to interplanetary speed, coasts for a few months, then arrives at Mars. Like the Space Shuttle Orbiters, it will slam into the Mars atmosphere and use drag to slow it down—parachutes for a ship this size are impractical—and then use its engines to land on its tail, just like in those old movies.

entry to Mars
Slowing down using the thin atmosphere of Mars will be a rough ride, but the only way to decelerate enough to land.


But we’re not quite done. To make the spaceship fully reusable (to save on cost per flight), it will need to tank back up and return to Earth (perhaps with people and supplies if needed). To do that, it’ll need to make its own fuel.

This part of the plan is probably the hardest, technologically speaking. The rocket and spaceship will use a new engine SpaceX calls Raptor (the first test model has already been built and underwent a test firing just the other day). It will be more powerful than the Merlins currently used by the Falcon 9, and will use extremely cold liquid methane for fuel. This has some advantages over current fuels; while tricky to design the engine, it does allow for more thrust  and a bigger rocket, but most importantly it can be made on Mars! There’s lots of water there in the form of ice, and carbon dioxide in the atmosphere. Using various methods, these can be processed into methane to make more fuel.

So there you go. Easy peasy, right?

Welllll …

Some Issues

There are some issues with this. For one, we’re not really sure how to make the fuel on Mars, or how much it will cost. The chemistry of it is understood, but in practical terms the ice has to be mined, purified, and processed, and all that has to be done in quantity. That’ll take a lot of machinery, and a whole lot of robust engineering to make sure it works right. Repairs will be difficult until the base becomes sufficient.

Nothing this large has ever been attempted before, either. Despite recent setbacks, SpaceX has been doing pretty well with the Falcon 9, and has learned a lot about bringing boosters back, making reusable vehicles, and the like.

But there’s a helluva long way to go to get to the point where this huge rocket can be built. They need to learn how to do autonomous docking in space (that’ll be tested next year with the Dragon capsule berthing to the space station). They need to relaunch a used booster, and not just once, but multiple times. And of course, SpaceX still hasn’t sent any humans to space.

I’m not saying any of those are show stoppers. Just that this is a long, long road, and SpaceX is just now pulling onto it.

Still, I have some bigger concerns. For example, a trip to Mars using the ITS will take roughly 80 to 140 days (Mars has an elliptical orbit, so sometimes the dance of the planets brings it closer to Earth than other times, so this is an average). This raises the danger of radiation. Normally this isn’t all that big a deal; in interplanetary space, levels are low. But if there’s a solar storm like a flare, this can send deadly waves of subatomic particles racing into space. If such an event occurs, astronauts will have to be protected.

Musk was remarkably cavalier about this, saying it’s not that big a deal. I disagree; it’s something engineers will have to plan for, especially given the sheer number of flights planned. Over 10,000 trips, the odds of a ship getting hit are very high indeed. Water is an excellent shield, and the ships will need plenty of it, so designing the transport to use it that way would be beneficial.

There’s also the issue of recycling air and water, and how that many people will get along for the months of hopefully uneventful travel through interplanetary space.

Also, it’s not clear to me what will happen when the first ships get to Mars. They’ll need protection from dust storms, from radiation, and also just a place to live. I know that this isn’t the kind of thing this presentation was meant to cover in detail, but some mention would’ve been nice to hear. If Musk really wants a million people to live on Mars, those first few will need shelter.

Mars Needs Money

Also, how this enormous undertaking will be financed is a bit hazy. Musk said that SpaceX is funding this right now, spending a few tens of millions of dollars per year on research. The Raptor engines have been funded privately, though recently the Air Force kicked in some dough). Eventually, once the final designs of the Falcon 9 are implemented, the company will spend more resources on it. They still need to get the Falcon Heavy off the ground as well, which hopefully will happen next year.

Raptor test
An actual photo of the recent test firing of the powerful Raptor engine.


The costs of developing and launching the ITS are formidable: It’ll cost more than $500 million just to manufacture a single rocket, spaceship, and tanker. Even if it’s reused many times, this is still a lot of cash, especially when you remember that Musk wants to launch thousands of these things.

SpaceX obviously can’t do it alone, and Musk said he hopes NASA and private companies can pitch in. There is some reason to do so; the engineering will be very useful and easy to spin off, and NASA is very interested in data SpaceX generates. The company is making money on contracts now, and heavy lift vehicles like the Falcon Heavy and the ITS booster could turn a profit for the company.

I strongly suspect that the ITS will cost far less than NASA’s Space Launch System, too, which will cost more than $1 billion per flight (and is not reusable). SLS hasn’t been built or launched yet, so we’ll have to see how it will compare to ITS. Musk hopes to complete the initial development of the first ITS booster in 2020, and send people to Mars in about 10 years or so.

That’s possible. SpaceX has plans to send an uncrewed Dragon capsule to Mars in 2018, though realistically, given inevitable delays, they may have to wait until the 2020 apparition to launch (the same year NASA will send the Mars 2020 rover there, too). Musk wants to send people to Mars by 2024 as well.

But we’re talking a lot of money, at least a $10 billion investment before money starts to be made back. Musk talked about the cost per person to go to Mars as a way to judge the efficacy of this, and more than once talked about people “buying a ticket” for $100,000 to $200,000. It’s possible he might sell some, given that it could be a round trip, but I’m not sure people will pony up that kind of money to go live on Mars until it’s a viable habitat.

So, Will This Work or Not?

So what’s the bottom line? Is this possible?

The answer is yes, it’s certainly possible. But is it doable?

That one I’m not sure about. I think it very well may be, but again fortune will have to smile down a lot on Musk and SpaceX.

Still. Musk has pulled a rabbit out of his space helmet more than once in the past. SpaceX was nearly bankrupt when it finally got a Falcon 1 rocket off the ground, and showed it could go to space. The loss of a vehicle in 2015 slowed but did not stop them, and neither will the more recent Falcon 9 loss. SpaceX has built up quite a bit of momentum, and the Falcon 9 is still operating at a more than 90 percent success rate. And their ability to develop their own engines and bring a booster back from space is very, very impressive (Blue Origin is doing this as well).

While I can’t say for 100 percent sure we’ll be seeing people going to Mars on a rocket with SpaceX’s logo on the side using the ITS … I wouldn’t bet against Musk.

Approaching Mars
How long before 100 people at a time will get a view like this?



And finally, there’s one more question: Why do this? What motivates Musk?

As he said at the announcement:

It would be an incredible adventure. I think it would be the most inspiring thing that I can possibly imagine. And life needs to be more than just solving problems every day. You need to wake up and be excited about the future. And be inspired, and want to live.

I agree. And while some people have quoted him as saying he “wants to die on Mars,” when I talked to him in 2015 about this he waved off this as a bit of headline link bait. Then why go, I asked him.

“Humans need to be a multiplanet species,” he replied.

I agree with that as well. It’ll happen, inevitably, if we choose to make it happen. Musk has made his choice. I hope it pays off. It very well might.

*Correction, Sept. 29, 2016: This post originally misidentified the International Astronautical Congress as the International Aeronautical Conference.

*Update, Sept. 30, 2016: The mass of the observatory was about five tons, but it also had a rocket booster attached that brought the total payload mass to more than 20 tons. Not incidentally, the shuttle Orbiters had masses of roughly 80 tons as well.