Meet the Next Generation of Planetary Rovers
Want to go scuba diving on the Saturnian moon Enceladus? Get in line. When NASA announced the discovery of a subsurface ocean the size of Lake Superior on the tiny moon it inspired a new rush of speculation about how we might land a rover on Enceladus' alluring surface.
“There’s such a large amount of interest in this small body,” Luciano Iess, lead author of the Endeladus study, told Motherboard last week. “You could deploy a rover that could penetrate through this rather thick ice layer with heat. You can melt the ice and then by gravity, the submarine would get pushed down and would, sooner or later, end up in the ocean. It’s complicated, but that’s the target.”
But Enceladus is only one of many such complicated targets positively begging to be explored. Roving around the Jovian moon Europa—which boasts a much larger subsurface ocean than Enceladus—has been on the to-do list for decades (and NASA might finally be getting around to it). Saturn's biggest moon, Titan, is another popular candidate. Though the Huygens probe pulled off a perfect landing in Titan's Shangri-la section in 2004, it was only able to send a few hours' worth of data back to Earth. Imagine how much more insight we could get into Titan's atmosphere and methane-rich oceans with a next-gen rover.
But as the list of extraterrestrial destination spirals upwards, so too does the need for cheaper, smarter, and more versatile rovers. This is especially true when it comes to more exotic destinations in the outer solar system. If we're seriously going to pursue Europa, Titan, Enceladus, and other bodies like them, we need to think beyond the “lab-on-wheels” setup. Bulky, expensive, and vulnerable, this design will have to make way for the extraterrestrial explorers of the 21st Century.
This is not to argue that the traditional rover model—a hefty science lab piggybacked on all-terrain wheels—should be phased out. After all, this design has racked up significant milestones on the moon and Mars. Curiosity has delved into the planet's aquatic history, while Opportunity is still chugging along discovering Martianballs at ten years old, far longer than NASA expected. And while China's Yutu rover is turning out to be a total drama queen, getting a mobile robot back on the lunar surface after 37 years is an accomplishment in itself.
Curiosity is still rocking it...for now. Image via NASA.
But what will these 'rovers of the future' look like? We reached out to Adrian K. Agogino, a researcher at the NASA's Intelligent Systems Division, for answers. Together with senior robotics researcher Vytas SunSpiral, Agogino has been working on a new rover design based on the concept of tensegrity—where tension meets integrity. Nicknamed the “Super Bot Ball,” this bundle of rods and cables looks like a high-tech tumbleweed, but it has the potential to leave traditional rovers in the Martian dust.
Motherboard: When most people think of rovers for planetary exploration, they think of the hefty Mars rovers. The Super Bot Ball concept seems to explode this model. What kind of challenges can a tensegrity-based explorer overcome that a traditional rover cannot?
When we look at traditional wheeled rovers, we are looking at a very delicate tool. It can get stuck, it can tip over, it can crash into things. Even more advanced concepts such as powerful rigid walking robots can fail over relatively mundane tasks, such as maxing out on torque because it is crawling over some small rocks at just the wrong angles.
We saw a tensegrity structure as something very robust and compliant. Something that will not get into a lot of trouble and something that can get out of a lot of trouble. Tensegrity structures are really good at absorbing impact forces because of their inherently compliant design. We are using this property to design a robot that can survive landing from orbit. Unlike traditional robots which need landing systems like airbags, this quality is inherent in the design of the tensegrity robot and thus it has this level robustness to collisions as it explores another planet.
With a traditional rover one has to be very careful about collisions or, worse, falling or rolling down a steep slope or cliff. Since planetary scientists are often interested in the exposed rock found on cliffs and mountains, these are exactly the regions they would like to send the rover to. With a tensegrity robot which can survive landing from orbit, these risks are greatly decreased, enabling a much more aggressive exploration strategy.
On your NASA project page, you describe tensegrities as "counter-intuitive tension structures with no rigid connections." Could you expand on the inner workings of these explorers? How big do you expect them to be?
A basic tensegrity structure is essentially made of cables and rods. The key thing is that the rods do not connect rigidly to each other. They only connect through cables. The counter-intuitive part is how something connected with cables can have rigidity as a whole.
The answer is the tension network. There is an interplay between the compression in the rods and the tension in the cables that allow the system as a whole to have a variable degree of rigidity. The tension network allows contact forces to diffuse through the whole structure, which allows for a system wide participation in absorbing the stress of impacts.
For the actual tensegrity robot the big issue is actuation: how do we change the shape of the tensegrity. Our current approach is to reel the cables in and out on a spool contained in an end-cap of the rod, though this could change in the future. Our current size goal is for each tensegrity rod to be about 1.5 meters in length.
Where are you in the development process?
We are currently working with a tensegrity ball robot that has a few cables that can be actuated. This is helping test our basic mechanical properties and control. We are also developing a new actuated tensegrity rod. The new rods will lead to our second-generation prototype, which should have significantly improved capabilities and efficient rolling locomotion. Within six months, we plan to put six of these rods together to create a tensegrity ball. This ball should have significant capabilities including rolling.
Motherboard: The Super Bot Ball has been billed as ideal for the exploration of Titan. Why the focus on that moon specifically? Could the model deployed on other planets and moons, even with extreme landscapes like Europa?
Adrian K. Agogino: Tensegrity robots can be helpful most anywhere, though Titan has an interesting use case. Long ago I did the calculation that in principle a person (in a protective suit) could be dropped from 500 kilometers above the surface of Titan and survive the landing without any parachute due to Titan's thick atmosphere and low gravity (note that entering the upper atmosphere from orbit and not burning up is an entirely different issue that needs to be resolved through heat shields).
This person would hit pretty hard, and a rover landing at the same speed would almost certainly break. However, a tensegrity robot could potentially land at this speed and be just fine. In fact we have performed drop tests from buildings that tend to confirm this.
Titan's other interesting property is it is actively changing, so things like the edges of lake shores likely change location depending on season. Yet due to its atmosphere details about the surface are difficult to monitor from orbit. Such an environment is exciting to science, but very problematic to navigate in a traditional rover. A tensegrity robot, though, should be robust enough to handle unexpected environments.
For other destinations such as Europa, a tensegrity robot would need some sort of primary landing system, but could still be significantly more economical than traditional landing systems, since it would not need the final part of the landing system such as airbags or the Curiosity rover's sky crane. In addition, once on the surface a tensegrity robot would retain all of its robustness and compliance advantages.
The Super Bot Ball close-up. Image via NASA-Ames/SunSpiral/Agogino.
Motherboard: A lot of our readers (myself included) are interested in how robotic planetary exploration will evolve over the coming decades. I'd love to get truly sci-fi with you. Other than tensegrity models, what are some other concepts that have the potential to radically change planetary exploration? Do you think traditional rovers will continue to be deployed, or will they be edged out for lighter, more durable models?
Adrian K. Agogino: The big trend that we are seeing in robotics today, of which tensegrity robots are an example, is the emergence of "soft machines". Traditional rigidly constructed robots are really good for high speed repetition of known tasks, such as factory automation, which is where the technology matured. But it turns out that they are very poor choices for interacting with dynamic natural environments—their rigidity means that any miscalculation about the external world can cause significant damage to themselves or those around them.
As such, as robots are increasingly being used outside the factory or laboratory, the technology is moving towards increased compliance and even incorporating soft deformable materials. There are many challenges to overcome, but this trend will continue into the future and tomorrow's robots will move more like animals in their ability to be soft and strong and adapt to their environment.
This Is One of the Clearest Images Ever Taken of the Universe
The Hubble Space Telescope, which has been NASA’s workhorse for incredible photos of the universe since it launched in 1990 (wow), has just done it again—the space agency just published one of the clearest images of the universe yet.
I guess if you consider “the universe” to include everything, a super high-res photo of your cat could qualify, but let’s be real here: What you’re seeing is a cross-section of the universe, showcasing objects that are one billion times fainter than those that you can see with your naked eye. Most of the things that look close are actually billions of light years apart, and most of them are billions of light years away from us. Check out the ultra high-res version here.
How’d the telescope capture it? The same way you capture something in the dark here on Earth—with a really long exposure. The telescope took the photos using infrared and standard sensors, with an exposure time of 14 hours. As you’ll see in this picture:
Image: NASA
Certain galaxies—we know them by the names Fred, Ginger, and the ultra common name Class B1608+656 (it was probably huge in the 80s)—are large enough to “visibly distort the light from object behind them,” which is why you’ll see those curved things behind them.
And, for comparison’s sake, here’s what the same thing looks like when you try to take a picture from an Earth telescope.
Image: NASA
Yeah, let’s keep some sort of telescope in space.
SpaceX Wants to Send a Positively Massive Rocket to Mars
The future of spaceflight will be powered by ion engines and warp drives, right? Not just yet. There is still some uncharted territory in the world of liquid-fueled rockets, which have been powering spacecraft since the 50s, and SpaceX is testing the waters with its new Raptor engine. It could be the engine that, if Elon Musk gets his wish, propels the first colonists to Mars.
Right now the Raptor looks like it will be developed to deliver 1 million pounds of thrust at launch, which is certainly a step up from SpaceX’s existing engines—SpaceX's Merlin 1D delivers about 147,000 pounds at launch. The Raptor will even beat out the Space Shuttle’s main engine, which delivered 375,000 pounds of thrust at launch. In other words, the Raptor is expected to be a huge engine, dwarfed only by the F-1 engine powering the gigantic Saturn V rocket.
Can SpaceX build a rocket engine to rival the giants? The firm has had good luck developing rocket engines in the past. Its Merlin 1D engine, which uses the traditional mixture of kerosene and liquid oxygen, has the highest thrust-to-weight ratio of any engine currently in use. But it still uses the same basic technology of all liquid rocket engines that came before it.
Liquid-fueled rockets work by mixing a fuel and an oxidizer in a combustion chamber before the mixture is ignited and blasted out of a nozzle. For a powerful reaction to occur, large quantities of the liquid fuel and the oxidizer must be fed into a rocket's combustion chamber quickly and under high pressure. This flow of liquids is driven by a turbopump, a system that is powered by a small amount of fuel “pre-burning.” A similar process happens to get the oxidizer into the combustion chamber.
SpaceX's Merlin 1D rocket engine being tested. Image: SpaceX
Liquid-fueled engines typically send a small amount of fuel and oxidizer through the preburners; the bulk of the liquids are sent directly into the combustion chamber. But what if this weren’t the case?
The US Air Force and NASA have both considered what's called a “full-flow cycle” design, which sends all fuel through turbopumps. It has one important advantage: more fuel and oxidizer passing through the preburners will drive the turbo pumps harder, increasing the pressure inside the combustion chamber and in turn the rocket engine’s performance.
A full-flow design has never been used in the United States, but it’s the kind of design SpaceX is currently pursuing for its Raptor engine.
SpaceX first revealed its new engine design at the AIAA Joint Propulsion conference in July of 2010. They were introduced as the powerhouses for the company’s future Falcon X and Falcon XX rockets. The first new engine was the Merlin 2, an engine of similar design but more efficient than the Merlin 1-D. The second engine presented was the Raptor, a staged combustion engine using liquid oxygen and hydrogen to power heavy rockets.
SpaceX says its future Falcon Heavy rocket will be the most powerful rocket in existence. Its first stage will be powered by 27 Merlin rocket engines, which are about an eighth the size of the Raptor engine planned. Image: SpaceX
The initial choice of liquid oxygen and hydrogen for Raptor was an interesting one. Cryogenic liquid hydrogen is hard to handle, must remain insulated, and has a lower density than kerosene. That means a liquid hydrogen tank for, say, the Falcon rocket would have to be larger than the current kerosene tank. Switching to liquid hydrogen would also mean a cost increase for a company that has long focused on lowering the price of getting each pound of cargo to orbit.
Elon Musk continued to hint a change in SpaceX’s rocket engines in the years after that 2010 conference. Notably, he’s mentioned a new liquid methane and oxygen rocket that would have enough power to launch his envisioned Mars Colonial Transporter, a fully reusable system that could theoretically transport 100 colonists at a time to the red planet.
Swapping kerosene for methane yields about the same performance. Kerosene scores points for being slightly lighter, but methane scores points for being the more efficient fuel. It’s also possible to source methane on Mars, and its a cleaner fuel that leaves little to no residue in a rocket engine’s plumbing.
In late 2013, SpaceX revealed that its Raptor was the powerful stage combustion engine fueled by liquid methane and liquid oxygen. In a configuration similar to the Falcon heavy, with nine of these full flow engines powering three rocket stages, SpaceX could have an incredibly powerful way to get to Mars on its hands.
Raptor isn’t quite ready to start sending massive payloads off the Earth, but it's getting there. SpaceX will be testing the Raptor engine in cooperation with NASA at the agency’s Stennis Space Center in Mississippi. As for Mars, Musk says SpaceX hopes its Raptor rocket will be ready for interplanetary flight within a decade.
Why SpaceX Is About to Launch Dinosaur Microbes and Toilet Germs Into Space
What's a surefire way to make a SpaceX launch even more exciting? Throw some dinosaur germs into the mix too. Microbes swabbed from one of our star dinosaur specimens, Sue the T-Rex, will be sent to the International Space Station on a Falcon 9 today (weather permitting, of course).
This giant leap for microbe kind is the brainchild of Project MERCCURI, an interdisciplinary project that fuses microbial research with public outreach. The point of the whole thing is to observe how microbial samples taken from different locations react to microgravity—a worthy experiment, considering how a cherry tree flown to space bloomed eight years early. The growth rates of each species will be monitored with a microplate reader, and will be compared to a control group in a UC Davis lab.
It's definitely not the first time microbial behavior has been studied in space, but this project is undeniably more playful than previous endeavors. The project is clearly designed to have a broad appeal, with an emphasis on the experiments being “microbial playoffs in...SPAAAAACE!”
Sue's Paenibacillus mucilaginosus germs will be competing against a number of other worthy challengers, recruited from diverse locations. Because the Science Cheerleaders are heavily involved in the project, the bulk of the samples were taken from football stadiums and fields, but some hail from more exotic locales. Pantoea eucrina was swabbed off of the Mercury Orbiter at the Smithsonian. Bacillus amyloliquefaciens calls the Liberty Bell home. And Leucobacter chironomi was raised in a toilet.
You can scroll through the 48 different competitors on the project's “sports card” page. The spacefaring microbes will be competing for three different football-themed awards. The Best Sprinter will go to the fastest growing microbe community, the Best Huddle will be awarded to the sample with the highest density, and whichever sample “takes off growing like crazy from the start” will snag the Best Tip Off award.
Naturally, we had to ask Jonathan Eisen—a Project MERCCURI's team members and professor of evolutionary biology—which micro-athletes he has his money on: “I think the likelihood of me being able to pick those winners has similar odds to someone winning Warren Buffet's March Madness contest,” he told me.
“I think I will pick my favorites by a randomization process," he said. "That being said, I want the one that came from the events involving kids.”
As zany as the whole project makes itself out to be, it's not just a publicity stunt. The spacefaring microbes will be constantly monitored and compared to their counterparts on Earth. The project is not only about sending Earth microbes into space—it's also about bringing those microbes living on the ISS back to Earth.
“One key thing we will also be doing is getting the astronauts to sample the microbes on the space station with cotton swabs,” Eisen said. “We are very excited to get some samples from the ISS as part of this project. I think we will also end up sequencing the genomes of all these organisms and seeing if anything in the genome relates to their activity in space, or if it relates to where they were isolated.”
While it's great to hear that we'll be getting some useful science out this experiment, I'll admit it: They had me at “dinosaur germs in space.”
An Inside Look at NASA's Deep Space Network
Eccentric chemical engineer and Jet Propulsion Lab co-founder Marvel "John" Whiteside Parsons was born a century ago this year, while JPL itself first got its name 70 years ago. This year also marks the 45th anniversary of the Moon landing which, it goes without saying, remains one of humankind's most significant accomplishments yet. But these other touchstones aside, this month NASA/JPL highlighted a much less publicized landmark in its history.
This year is the 50th birthday of NASA/JPL’s Deep Space Network, the government’s global collection of massive antenna arrays that control unmanned space probes within Earth's orbit and beyond. If you've wondered how NASA stays in contact with the Voyager spacecraft across billions of miles of space, the DSN is to thank.
Because the DSN doesn't get as much attention as it probably should, NASA/JPL recently hosted a semi-public "NASA Social," with visits to its Pasadena facilities as well as California's own Goldstone Deep Space Communications Complex (GDSCC) in the Mojave Desert. The goal was to help spread the word about the DSN through social media via 50 lucky people with Twitter accounts, each selected at random from a pool of 500 others who signed up for the event on NASA/JPL's website. They were joined by a few representatives from the actual media, too, including yours truly.
NASA/JPL Mission Control Center. Image: Tanja M. Laden
The DSN is a collection of three advanced communications platforms with enormous and sophisticated antennas that exchange data with NASA's missions in space. NASA’s three deep-space networks are located in Spain, Australia, and California, and are strategically placed 120 degrees apart in longitude in order to afford constant contact with spacecraft while the Sun rises and sets on the equidistant parts of the earth.
All three facilities are managed by the Jet Propulsion Lab in Pasadena, with the US.-based antennas located at the GDSCC, which sits some 150 miles northeast of JPL on the grounds of the US Army’s Ft. Irwin National Training Center. Given the distance between JPL and Goldstone, it made sense for NASA/JPL to spread out the 50th anniversary tour over the course of two days.
On the first day, the group toured the Jet Propulsion Lab in Pasadena. For anyone living in Southern California, it's not exactly difficult to get into JPL. Not only does it host regular open houses, but JPL also offers free weekly two-hour public tours for small groups, along with special excursions for schools and other organizations.
if you happen to know someone who works at JPL, you can be signed in, just like at any office with security at the front door—except this one is host to rocket engineers, not spreadsheets. As yet another indication of JPL's relatively open relationship with the community, there's also a museum and two gift stores filled with NASA/JPL-emblazoned merchandise, such as mugs, t-shirts, and astronaut outfits for kids.
Mars Yard III. Image: Tanja M. Laden
Once everyone was inside JPL, the group visited the Mars Yard, where prototypes of NASA’s robotic engineering models are tested in a desolate, Mars-like environment. Developed by the Mars Science Laboratory, it’s actually the third Mars Yard built by JPL. The Mars Yard III is about 215 feet by 115 feet in size, resembling the early stages of a major construction project, yet the groundwork is the project itself.
The uneven landscape, rugged rock formations, and bumpy terrain are all based on images returned to Earth from Mars rovers via the DSN, providing a simulated obstacle course for future rovers. While the paved portions obviously don't look like anything on Mars, it's all meant to test the agility and durability of the rovers before they are launched into space. There's also a garage that stores the robotic models, along with computers, measuring devices, and other necessary requirements for field-testing the mechanisms.
Spacecraft Assembly Facility. Image: Tanja M. Laden
The visitors also stopped by the viewing gallery above the Spacecraft Assembly Facility's clean room inside building 179, where specialists dressed in sterile plastic caps, booties, and billowy white overcoats construct spacecraft and instruments for future missions.
The room was built in 1961 for the Ranger program's unmanned space missions, which obtained images of the Moon, along with the Mariner program's interplanetary missions to Mercury, Venus, and Mars. There's a different insignia on the wall representing each vehicle built in the now-uncontaminated room—back in the day, scientists and engineers were actually allowed to smoke inside.
Oddly enough, NASA/JPL recently discovered a new species of microbe that's only been seen in a pair of clean rooms, one in Florida and one in South America. But everything appears to be going as planned in JPL's clean room, without the potential interference of weird new microorganisms.
Right now, JPL is using the space to finalize assembly on the Soil Moisture Active Passive (SMAP) radar spacecraft, which aims to provide better management of Earth's water resources through analysis of freeze and thaw states. The Spacecraft Assembly Room is also getting ready to finish putting together the ISS-RapidScat instrument, which will head to the International Space Station later this year in order to provide more detailed weather forecasts by measuring the direction and wind speed of ocean surfaces.
NASA/JPL Mission Control Center. Image: Tanja M. Laden
After checking out the clean room, everyone had the chance to actually sit in the mission support area in building 230, also known as the Space Flight Operations Facility (SFOF), where JPL engineers worked on the now-famous 2012 landing of the Curiosity over as the world watched on TV.
The area is linked to the awe-inspiring Mission Control Center, where engineers communicate with spacecraft across the solar system using the DSN. This is where NASA manages nearly all of its exploration of deep space, including exploration of other planets in our solar system. In 1985, the SFOF was declared a National Historic Landmark and is on the National Register of Historic Places. There's even a plaque on the floor in the middle of the Mission Control Center that reads "The Center of the Universe: 'Dare Mighty Things.’"
34 meter Beam Waveguide Cluster. Image: Tanja M. Laden
The next day, we paid a visit to GDSCC, located in a remote area 40 miles west of Barstow, about halfway between Los Angeles and Las Vegas. Compared to JPL, visiting Goldstone is an extended procedure, even though they also provide occasional tours.
California's part of the DSN is located at the US Army's Fort Irwin National Training Center for convenient built-in security. Visitors need prior approval to drive onto the premises, and if they manage to get past the gate, their cars are frequently searched. Everyone is encouraged to participate in a security briefing before exploring Goldstone, and obviously, they are required to be escorted at all times. And with the massive antennas at Goldstone located about 10-15 miles from each other, each antenna has another checkpoint with its own guards.
Apollo 26 Meter X-Y Antenna. Image: Tanja M. Laden
Unlike at JPL, there’s really not much to see at Goldstone besides the ten enormous and sophisticated satellite antennas. But the power and importance of these instruments are a great counterpoint to the attractions at JPL, especially since the dishes are responsible for exchanging data with NASA/JPL's missions in space.
Together with the DSN’s other facilities in Spain and Australia, Goldstone is part of the most powerful space-exploration telecommunications system in the world, overseeing more than 30 spacecraft missions. And not only does the DSN support robotic travel to distant planets as well as telescopes seeking out new ones, but it’s responsible for navigating spacecraft and monitoring asteroids, too.
DSS 14 "Mars" 70 meter antenna. Image: Tanja M. Laden
After the DSN dishes, we stopped by Goldstone's Apollo Valley, site of the eponymous 85-foot wide Apollo antenna. The antenna was built exclusively for the Apollo program and received the first audio transmission from the Moon.
If the Apollo antenna seemed large, it was dwarfed by the 24-story tall, 230-foot-wide Mars antenna, which once supported the Voyager 2 spacecraft in its mission to Neptune. In the end, the exhausting two-day field trip was capped off with a ribbon-cutting for Goldstone Tunnel Display, a space-science exhibition located in the narrow, catacomb-like walkway beneath the Mars antenna.
Another shot of Goldstone's 70 meter. Image: NASA/JPL-Caltech
Without GDSCC and the DSN, JPL wouldn’t be able to access the crucial information it needs in order to control the spacecraft and instruments it sends out to study planets and their freaky moons in the solar system. JPL wouldn’t be able to access images and other forms of information about all the comets, meteoroids, asteroids, and whatever else is out there, either.
Meanwhile, without the efforts of JPL, the DSN wouldn’t have a reason to exist, because there wouldn’t be anything to communicate with in the first place. The two entities are really part of a symbiotic system that would hardly be productive if they functioned independently of each other. So whenever people gush about the sexy, top-secret efforts going on at JPL, it’s worth remembering that those efforts wouldn't anywhere without a collection of gigantic satellite antennas out in the middle of nowhere.
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