If you’ve seen at least one other episode of the Guide to Space, you know I’m obsessed about the Fermi Paradox. This idea that the Universe is big and old, and should be teeming with life. And yet, we have no evidence that it exists out there. We wonder, where are all the aliens?
Ah well, maybe we’re in a cosmic zoo, or maybe the Universe is just too big, or the laws of physics prevent any kind of meaningful travel or communications. Fine. I doubt it, but fine.
As we’ve demonstrated here in our own corner of the galaxy, it’s not our weak fleshy bodies that will be doing the hard work of exploring the Solar System, and eventually the galaxy, it’ll be the robots.
So a better question might be, where are all the robots? At the time that I’m writing this video, we’re in October of 2016. If you’re watching this on a video device years in the future, the robot uprising and apocalypse hasn’t happened yet.
The most sophisticated walking robots can barely lurch around and they’re laughably slow, 3D fabrication is an inefficient process, and our artificial intelligence devices are pretty dumb, barely able to understand when I ask for directions.
But even so, our robots have helped us explore the Solar System, and helped us see things with cameras that our fleshy meat eyeballs may never experience. Robots from Earth have orbited asteroids, visited comets, observed Mars from orbit and the ground, and even flown past Pluto.
In the coming decades, many new robotic missions will continue this era of exploration, maybe floating in the cloud tops of Venus, sailing the hydrocarbon seas of Titan, flying in the skies of Mars, or exploring the vast oceans under the ice of Europa.
It makes sense then, for us to eventually get around to sending a robotic spacecraft to another star. Based on our current technology, it’ll be incredibly complicated and expensive, but there’s nothing in the laws of physics that prevents it.
And if we’re going to send a robot to another star system, we might as well make it a factory, capable of creating another version of itself. Find an asteroid with all the raw materials to make more robot factories, and send them off to other stars, where they can make more copies, and so on, and so on.
What I’m describing is the concept of a von Neumann probe, named after the mathematician John von Neumann. He was investigating the implications of self-replicating robots in the 1940s, and imagined non-biological “Universal Assembler”, devices that could make copies of themselves.
Von Neumann didn’t apply the idea to spacecraft, but others like George “Spheres” Dyson understood that out in space, there was a nearly limitless amount of raw materials for spacecraft to build copies of themselves.
Even though the Milky Way measures 120,000 light-years across and contains 100 to 400 billion stars, self-replicating robot factories traveling at just 10% the speed of light could colonize the entire galaxy in about 10 million years. That’s the power of exponential exploration.
Think about it. All it takes is for a single clever alien engineer to craft a single robotic factory. That factory builds copies of itself which fly off to other stars. Once they get there, they build more copies of themselves, and so on and so on.
Seriously, in the 13.8 billion years that the Universe has been around, why didn’t a single alien engineer do this?
The cosmologist Frank Tipler concluded that this was such an obvious thing to do that he wrote a paper in the 1980s called “Extraterrestrial intelligent beings do not exist.” Carl Sagan found the argument troubling, proposed that aliens would be concerned with environmental collapse and would restrict the use of this kind of technology.
Why haven’t we received signals from extraterrestrials yet? Maybe because it’s inefficient. It’s much more efficient to send physical probes to communicate with other civilizations.
Remember 2001? I know it was a pretty complicated movie, but that was the point. The aliens let us know we’re not alone by sending their robotic spacecraft to our Solar System. That’s what those monoliths were for. Well, sort of. They were a message, they were a kind of encyclopedia, an evolutionary accelerator and doomsday device, all rolled up in one.
Still think it’s important to take your fleshy meat body to experience other worlds personally? No problem. Modify your von Neumann probes to be terraforming probes. Instead of merely building factories, they travel to other star systems, identify the planets that could be made habitable for humans, and then get to work.
We’ve written many articles about what could be done to terraform worlds here in the Solar System, and that work would mostly be done with robots anyway. Some robots could redirect asteroids and comets to supply raw materials, robotic shades to cool planets down, ground-based factories could change the atmosphere to something breathable.
You could even imagine robotic nurseries, carrying seeds and genetic material for plants and animals. They could get these planets livable, so that when our descendants arrive, the world is ready to go and fully habitable.
There’s a darker idea too, the concept of Berserker Probes. These were first put forth by the science fiction author Fred Saberhagen. Imagine aliens send an initial scouting robotic spacecraft to a star system to search for life, and any possible competition to the colonization of the galaxy.
If a potential competitor is found, the robotic spacecraft redirect a bunch of asteroids at the habitable planet to scour it free of life.
Then the terraforming robots move in and make the place livable for the aliens. And then the aliens move in, blissfully unaware of who used to live on the planet.
Maybe other aliens anticipating this threat, create their own police von Neumann probes, designed to seek out Berserkers and defend against them.
If you play video games, the best telling of this story is through the Mass Effect series, and their Reapers. Edge of Tomorrow was about defending Earth from terraforming robots.
Although I find the Fermi Paradox puzzling, I get that it’s probably hard for aliens to travel and communicate across the vast distances of space. But shouldn’t we at least see their robots?
Actually, based on what I just said, I’m think I’m okay if we never meet their robots.
Want to learn more about von Neumann probes? PBS Space Time just did a great video on it too. You should check it out.
In our last episode, we talked about what it’ll take to navigate across the Solar System. In this episode we scale things up and speculate how future civilizations will navigate to other stars and even other galaxies.
It’s hard enough finding your way around planet Earth, but what do you do when you’re trying to find your way around the Solar System? Today we’ll talk about how spacecraft navigate from world to world.
Freelance animator and storyboard artist Stanley VonMedvey has started using his remarkable talents to create short videos to explain a pretty complex topic: how spacecraft work. He’s made two so far and they are wonderfully concise, clear and easy to understand. Plus his hand-drawn animations are incredible.
Here’s the first one that caught my eye, about the space shuttle and the concept of reusability:
VonMedvey describes himself as “completely obsessed with and fascinated by space exploration,” and he wants to share what he’s learned over the years about spaceflight.
He’d like the opportunity and resources to make more videos, and has started a Patreon page to help in this process. Right now, he creates the videos on his own (using the time-honored home-recording technique of draping a blanket over his head) in his home officee.
“I’d like to make a lot more videos,” he writes on Patreon, “explaining things like Hohmman transfers and laser propulsion and the construction techniques of O’Neill cylinders. I want to make long form videos (2-3 minutes) that explain a general idea, and short form videos (30 seconds) that cover a single word, like “ballistics” or “reaction control”.
The second video he’s done covers expendable launch vehicles:
Enjoy these great videos and if you’d like to see more, consider supporting his work. See more of his drawings at his website.
Europa is probably the best place in the Solar System to go searching for life. But before they’re launched, any spacecraft we send will need to be squeaky clean so don’t contaminate the place with our filthy Earth bacteria. Continue reading “Will We Contaminate Europa?”
Like me, you’re probably a little ego-geocentric about the importance of Earth. It’s where you were born, it’s where you keep all your stuff. It’s even where you’re going to die – I know, I know, not you Elon Musk, you’re going to “retire” on Mars, right after you nuke the snot out of it.
For the rest of us, Earth is the place. But in reality, when it comes to planets, this is somebody else’s racket. This is Jupiter’s Solar System, and we all sleep on its couch.
Jupiter accounts for 75% of the mass of the planets of the Solar System, nearly 318 times more massive than Earth, and isn’t just the name of everyone’s favorite secret princess. It’s the 1.9 × 10^27 kilogram gorilla in the room. Whatever Jupiter wants, Jupiter gets. Jupiter hungry? JUPITER HUNGRY.
What Jupiter apparently wants is to throw our stuff around the Solar System. Thanks to its immense gravity, Jupiter yanks material around in the asteroid belt, preventing the poor space rocks from ever forming up into anything larger than Ceres.
Jupiter gobbles up asteroids, comets, and spacecraft, and hurtles others on wayward trajectories. Who knows how much mayhem and destruction Jupiter has gotten into over the course of its 4.5 billion years in the Solar System.
Some scientists think we owe our existence to Jupiter’s protective gravity. It greedily vacuums up dangerous asteroids and comets in the Solar System.
Other scientists totally disagree and think that Jupiter is a bully, perturbing perfectly safe comets and asteroids into dangerous trajectories and flushing earth’s head in the toilet during recess.
Which is it? Is Jupiter our friend and protector, or evil enemy. We’ve already figured out how to dismantle you Jupiter, don’t make us put our plans into action.
Some of the most dangerous objects in the Solar System are long-period comets. These balls of rock and ice come from the deepest depths of the Oort cloud. Some event nudges these death missiles into trajectories that bring them into the inner Solar System, to shoot past the Sun and maybe, just maybe, smash into a planet and kill 99.99999% of the life on it.
There’s a pretty good chance some of the biggest extinctions in the history of the Earth were caused by impacts by long period comets.
As these comets make their way through the Solar System, they interact with Jupiter’s massive gravity, and get pushed this way and that. As we saw with Comet Shoemaker-Levy, some just get consumed entirely, like a tasty ice-rock sandwich.
The theory goes that Jupiter pushes these dangerous comets out of their murder orbits so they don’t smash into Earth and kill us all.
But a competing theory says that Jupiter actually diverts comets that would have completely missed our planet into deadly, Earth-killing trajectories.
Will the Sailor Scouts provide us any clues? Who can say?
Here’s friend of the show, Dr. Kevin Grazier, a planetary scientist and scientific advisor for many of your favorite sci-fi TV shows and movies.
… [ see video for Interview with Dr. Grazier about Jupiter]
So which is it? Is Jupiter our friend or enemy? We’ll need to run more simulations and figure this out with more accuracy. And until then, it’s probably best if we just tremble in fear and worship Jupiter as a dark and capricious god until the evidence proves otherwise. It’s what Pascal would wager.
What are some other theories you’ve heard about and you’d like us to dig in further? Make some suggestions in the comments below.
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If you’re into other facts about our Solar system here’s a link to our Solar system playlist. Thanks to Ben Johnson and Tal Ghengis, and the members of the Guide to Space community who keep these shows rolling. Love space science? Want to see episodes before anyone else? Get extras, contests, and shenanigans with Jay, myself and the rest of the team. Get in on the action. Click here.
It’s a staple of scifi, and a requirement if we’re going to travel long-term in space. Will we ever develop artificial gravity?
It’s safe to say we’ve spent a significant amount of our lives consuming science fiction.
Berks, videos, movies and games.
Science fiction is great for the imagination, it’s rich in iron and calcium, and takes us to places we could never visit. It also helps us understand and predict what might happen in the future: tablet computers, cloning, telecommunication satellites, Skype, magic slidey doors, and razors with 5 blades.
These are just some of the predictions science fiction has made which have come true.
Then there are a whole bunch of predictions that have yet to happen, but still might, Fun things like the climate change apocalypse, regular robot apocalypse, the giant robot apocalypse, the alien invasion apocalypse, the apocalypse apocalypse, comet apocalypse, and the great Brawndo famine of 2506. Continue reading “Could We Make Artificial Gravity?”
On Sunday, May 31, the Cassini spacecraft will perform its last close pass of Hyperion, Saturn’s curiously spongelike moon. At approximately 9:36 a.m. EDT (13:36 UTC) it will zip past Hyperion at a distance of about 21,000 miles (34,000 km) – not its closest approach ever but considerably closer (by 17,500 miles/28,160 km) than it was when the image above was acquired.*
This will be Cassini’s last visit of Hyperion. It will make several flybys of other moons within Saturn’s equatorial plane over the course of 2015 before shifting to a more inclined orbit in preparation of the end phase of its mission and its operating life in 2017.
At 255 x 163 x 137 miles (410 x 262 x 220 km) in diameter, Hyperion is the largest of Saturn’s irregularly-shaped moons. Researchers suspect it’s the remnant of a larger body that was blown apart by an impact. Hyperion’s craters appear to have a “punched-in” look rather than having been excavated, and have no visible ejecta or secondary craters nearby.
Hyperion orbits Saturn in an eccentric orbit at a distance of over 920,000 miles (1.48 million km)…that’s almost four times the distance our Moon is from us! This distance – as well as constant gravitational nudges from Titan – prevents Hyperion from becoming tidally locked with Saturn like nearly all of its other moons are. In fact its rotation is more of haphazard tumble than a stately spin, making targeted observations of any particular regions on its surface virtually impossible.
Images from the May 31 flyby are expected to arrive on Earth 24 to 48 hours later.
As small as it is Hyperion is Saturn’s eighth-largest moon, although it appears to be very porous and has a density half that of water. Read more about Hyperion here and see more images of it from Cassini here and here.
For more than four years NASA’s MESSENGER spacecraft has been orbiting our solar system’s innermost planet Mercury, mapping its surface and investigating its unique geology and planetary history in unprecedented detail. But the spacecraft has run out of the fuel needed to maintain its extremely elliptical – and now quite low-altitude – orbit, and the Sun will soon set on the mission when MESSENGER makes its fatal final dive into the planet’s surface at the end of the month.
On April 30 MESSENGER will impact Mercury, falling down to its Sun-baked surface and colliding at a velocity of 3.9 kilometers per second, or about 8,700 mph. The 508-kilogram spacecraft will create a new crater on Mercury about 16 meters across.
The impact is estimated to occur at 19:25 UTC, which will be 3:25 p.m. at the John Hopkins University Applied Physics Lab in Laurel, Maryland, where the MESSENGER operations team is located. Because the spacecraft will be on the opposite side of Mercury as seen from Earth the impact site will not be in view.
But while it’s always sad to lose a dutiful robotic explorer like MESSENGER, its end is bittersweet; the mission has been more than successful, answering many of our long-standing questions about Mercury and revealing features of the planet that nobody even knew existed. The data MESSENGER has returned to Earth – over ten terabytes of it – will be used by planetary scientists for decades in their research on the formation of Mercury as well as the Solar System as a whole.
“For the first time in history we now have real knowledge about the planet Mercury that shows it to be a fascinating world as part of our diverse solar system,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate. “While spacecraft operations will end, we are celebrating MESSENGER as more than a successful mission. It’s the beginning of a longer journey to analyze the data that reveals all the scientific mysteries of Mercury.”
On April 6 MESSENGER used up the last vestiges of the liquid hydrazine propellant in its tanks, which it needed to make course corrections to maintain its orbit. But the tanks also hold gaseous helium as a pressurizer, and system engineers figured out how to release that gas through the complex hydrazine nozzles and keep MESSENGER in orbit for a few more weeks.
On April 24, though, even those traces of helium will be exhausted after a sixth and final orbit correction maneuver. From that point on MESSENGER will be coasting – out of fuel, out of fumes, and out of time.
“Following this last maneuver, we will finally declare MESSENGER out of propellant, as this maneuver will deplete nearly all of our remaining helium gas,” said Mission Systems Engineer Daniel O’Shaughnessy. “At that point, the spacecraft will no longer be capable of fighting the downward push of the Sun’s gravity.
“After studying the planet intently for more than four years, MESSENGER’s final act will be to leave an indelible mark on Mercury, as the spacecraft heads down to an inevitable surface impact.”
But MESSENGER scientists and engineers can be proud of the spacecraft that they built, which has proven itself more than capable of operating in the inherently challenging environment so close to our Sun.
“MESSENGER had to survive heating from the Sun, heating from the dayside of Mercury, and the harsh radiation environment in the inner heliosphere, and the clearest demonstration that our innovative engineers were up to the task has been the spacecraft’s longevity in one of the toughest neighborhoods in our Solar System,” said MESSENGER Principal Investigator Sean Solomon. “Moreover, all of the instruments that we selected nearly two decades ago have proven their worth and have yielded an amazing series of discoveries about the innermost planet.”
The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft launched on August 3, 2004, and traveled over six and a half years before entering orbit about Mercury on March 18, 2011 – the first spacecraft ever to do so. Learn more about the mission’s many discoveries here.
The video below was released in 2013 to commemorate MESSENGER’s second year in orbit and highlights some of the missions important achievements.