Artist concept of a solar sail demonstration mission that will use lasers for navigation. Credit: NASA.
Since the beginning of the space age, radio waves have been used for communication with spacecraft. But last month, NASA’s Lunar Laser Communication Demonstration (LLCD) made history by using a pulsed laser beam to transmit data over the 385,000 km (239,000 miles) between the Moon and Earth at a record-breaking download rate of 622 megabits per second (Mbps). This was NASA’s first system for two-way communication using a laser instead of radio waves. In our previous article today, we described how NASA will test out the Optical PAyload for Lasercomm Science (OPALS) on the International Space Station to demonstrate how videos can be beamed to Earth via laser beam.
What are the challenges in testing out an entirely new way of doing communications and other systems like navigation using lasers in space?
Don Cornwell, LLCD manager, discusses the challenges and successes they’ve had so far in this new video:
“The big change is the ability to do it by light, because the data rates that we’ve now done are just the opening shot, so to speak,” Cornwell said. “Radio communications systems have served us very well for the past 50 years but they are starting to run out of bandwidth, so in other words because of the frequency they use you can only modulate a certain portion of that frequencies and unless you move to higher frequencies – and light is a higher frequency than radio waves– you can’t squeeze a lot more bandwidth out, but the light systems in space, … we’ve now opened up a whole new field where we’re getting started , but the sky’s the limit regarding how much we can do there.”
Using lasers will allow for increased bandwidth for image resolution and 3-D video transmission from deep space, as well as allowing for tele-operation for long distances, such as from the Earth to the Moon.
LLCD is a short-duration experiment and the precursor to NASA’s long-duration demonstration, the Laser Communications Relay Demonstration (LCRD). LCRD is a part of the agency’s Technology Demonstration Missions Program, which is working to develop crosscutting technology capable of operating in the rigors of space. It is scheduled to launch in 2017.
Meanwhile, NASA has three other laser technology demonstration missions in the offing, likely launching in 2015 and 2016. One is a solar sail demonstration will enable propellantless laser in-space navigation for missions such as advanced geostorm warning, economic orbital debris removal, and deep space exploration.
Artist's conception of an astronaut installing the Optical PAyload for Lasercomm Science (OPALS) experiment, which will be installed on the Earth-facing side of the International Space Station. Credit: NASA
Videos will beam to Earth on a laser beam in a technology demonstration coming to the International Space Station soon, says NASA’s Jet Propulsion Laboratory.
The Optical PAyload for Lasercomm Science (OPALS) plans to move videos from space to an Optical Communications Telescope Laboratory in Wrightwood, Calif. Each demonstration test will last about 100 seconds, while the station and the ground receiver can “see” each other.
While the experiment sounds awesome for sending back “home videos” from space, NASA is more touting it as a boon for transferring loads of scientific data back to Earth.
“The scientific instruments in near-Earth and deep-space missions increasingly require higher communication rates to transmit their gathered data back to Earth or to support high-data-rate applications (e.g., high-definition video streams),” stated the OPALS webpage at NASA’s Jet Propulsion Laboratory.
“Optical communications (also referred to as ‘lasercomm’) is an emerging technology wherein data is modulated onto laser beams, which offers the promise of much higher data rates than what is achievable with radio-frequency (RF) transmissions.”
How the Optical PAyload for Lasercomm Science (OPALS) experiment will work on the International Space Station. Credit: NASA
The experiment page (last updated in May) says it is intended to work for about a year, with the current Expedition 37/38 and forthcoming 39/40 crews. That said, it appears the payload is not aboard station yet.
A July update from NASA said the SpaceX Dragon spacecraft is supposed to ferry OPALS to space. There hasn’t been a Dragon flight since that time, but SpaceX is listing one more for 2013 on its launch manifest.
Diagram of the Optical PAyload for Lasercomm Science (OPALS) experiment. It includes three elements: (1) a sealed container that includes the laser, a power board and avionics (2) an optical gimbal transceiver that has an uplink camera, and laser collimater for downlink (3) a Flight Releasable Attachment Mechanism (FRAM), a mechanical and electrical link to the International Space Station and launch vehicle. Credit: NASA
Laser communication hit headlines earlier this fall when the NASA Lunar Atmosphere and Dust Environment Explorer (LADEE) sent a packet of information by laser from the moon, breaking records in terms of download rate (622 megabits per second).
Almost every part of a rocket is destroyed during the launch and re-entry into the Earth’s atmosphere. This makes spaceflight really expensive. Rocket delivery of even a single kilogram into orbit costs tens of thousands of dollars. But what if we could just place our payloads directly into orbit, and didn’t need a rocket at all?
This is the idea of a space elevator, first envisioned by the Russian rocket scientist Konstantin Tsiolkovsky in 1895. Tsiolkovsky suggested building a tower all the way up to geostationary orbit, this is the point where a satellite appears to hang motionless in the sky above the Earth. If you could carry spacecraft all the way up to the top, and release them from that tower they’d be in orbit, without the expense of a discarded rocket. A fraction more energy and they’d be traveling away from the Earth to explore the Solar System.
The major flaw with this idea is that the entire weight of the tower would be compressing down on every part below. And there’s no material on Earth, or in the Universe, that can handle this kind of compressive force. But the idea still makes sense.
Newer thinking about space elevators propose using a cable, stretched out beyond geostationary orbit. Here the outward centripetal force counters the force of gravity, keeping the tether perfectly balanced. But now we’re dealing with the tensile strength of a cable tens of thousands of kilometers long.
Imagine the powerful forces trying to tear it apart. Until recently, there was no material strong enough to withstand those forces, but the development of carbon nanotubes has made the idea more possible.
How would you build a space elevator? The most reasonable idea would be to move an asteroid into geostationary orbit – this is your counterbalance. A cable would then be manufactured on the asteroid, and lowered down towards the Earth.
As the cable extends down, the asteroid is orbited further from the Earth, keeping everything in balance. Finally, the cable reaches the Earth’s surface and is attached to a ground station.
Artists concept of a space elevator. Credit: Caltech
Solar powered machines are attached to the space elevator and climb up from the surface of the Earth, all the way to geostationary orbit. Even traveling at a speed of 200 km/hour, it would take the climber almost 10 days to make the journey from the surface to an altitude of 36,000 kilometers. But the cost savings would be dramatic.
Currently, rockets cost about $25,000 per kilogram to send a payload to geostationary orbit. A space elevator could deliver the same payload for $200 per kilo.
Obviously there are risks associated with a megastructure like this. If the cable breaks, portions of it would fall to Earth, and humans traveling up in the elevator would be exposed to damaging radiation in the Earth’s Van Allen belts.
Building a space elevator from Earth is at the very limits of our technology. But there are places in the Solar System which might make much more useful places to build elevators.
The Moon, for example, has a fraction of the Earth’s gravity, so an elevator could operate there using commercially available materials. Mars might be another great place for a space elevator.
Whatever happens, the idea is intriguing. And if anyone does build a space elevator, they will open up the exploration of the Solar System in ways that we can’t even imagine.
Screengrab from the WildCat video from Boston Dynamics.
This is both wonderful and terrifying. A DARPA-funded four-legged robot named WildCat is being developed by a company called Boston Dynamics (tagline of “Changing Your Idea of What Robots Can Do”). They’ve previously developed a humanoid capable of walking across multiple terrains called Atlas, and the scarily-fast Cheetah which set a new land-speed record for legged robots. But the WildCat is a brand new robot created to run fast on all types of terrain, and so far its top speed has been about 16 mph on flat terrain using both bounding and galloping gaits.
The video, released yesterday, shows WildCat’s best performance so far. Don’t let the sound fool you — yes, it does sound like a weed-whacker. But as soon as it raises up off its haunches, you know you’re doomed.
I’ve been trying to figure out what sci-fi equivalent might describe it best: the Terminator’s pet? A lethal, non-fuzzy Daggit from Battlestar Galactica? An AT-AT Walker on speed?
Astrobotic's model rover explores a mine on Earth to train for lunar lava tunnels (Video screenshot)
Ever since (and most likely long before) the first tantalizing glimpses of a lunar lava tube and skylight were captured by Japan’s Kaguya spacecraft in 2009, scientists have been dreaming of ways to explore inside these geological treasures. Not only would they provide valuable information on the movement of ancient lunar lava flows, but they could also be great places for future human explorers to set up camp and be well-protected from dangerous solar and cosmic radiation.
But before human eyes will ever peer into the darkness of a lava tube on the Moon, robotic rovers will roll along their silent floors — at least, they will if Google Lunar XPRIZE competitor Astrobotic has anything to say about it.
Last month, engineer and Astrobotic CEO Dr. Red Whitttaker talked to NASA about why they want to explore a Moon cave and the history and progress of their project. Check it out below:
“Something so unique about the lava tubes is that they are the one destination that combines the trifecta of science, exploration, and resources.”
– Dr. William “Red” Whittaker, CEO Astrobotic Technology, Inc.
The international Google Lunar XPRIZE aims to create a new “Apollo” moment for a new generation by driving continuous lunar exploration with $40 million in incentive-based prizes. In order to win, a private company must land safely on the surface of the Moon, travel 500 meters above, below, or on the lunar surface, and send back two “Mooncasts” to Earth… all by Dec. 31, 2015.
Astrobotic Technology Inc. is a Pittsburgh-based company that delivers affordable space robotics technology and planetary missions. Spun out of Carnegie Mellon University’s Robotics Institute in 2008, Astrobotic is pioneering affordable planetary access that promises to spark a new era of exploration, science, tourism, resource utilization and mining. (Source)
SpaceX SuperDraco inconel rocket chamber w regen cooling jacket emerges from EOS 3D metal printer. Via Elon Musk on Twitter.
We knew SpaceX CEO Elon Musk was powerful, but now he’s gone all Ironman on us. Last week on Twitter he posted a teaser, saying, “Will post video of designing a rocket part with hand gestures & immediately printing in titanium.”
And now, here it is.
“I believe we’re on the verge of a major breakthrough in design and manufacturing,” says Musk in the video, “in being able to take a concept of something from your mind and translate into a 3-D object intuitively on the computer, then make that virtual 3-D object real just by printing it. It’s going to revolutionize manufacturing and design in the 21st century.”
See a montage of images of a SuperDraco rocket part made of Inconel-X, an austenitic nickel-chromium-based superalloy, emerge from a 3-D printer:
Musk and his design team have been working on using natural gesture-based interaction with a computer-aided design program called Leap Motion, allowing designers to work quickly to create parts, and then equally as quick, use 3-D printing in a metal superalloy to create the part.
The Kirobo talking robot on the ISS. Credit: Toyota.
The talking robot launched to the International Space Station in August has sent its first audio/visual message to Earth. Kirobo, the mini Japanese robot — which appears to have the bravado of Buzz Lightyear and the cuteness of WALL-E — is just .34 meters (13.4-inches) long. Kirobo is designed to be able to have conversations with its astronaut crewmates and to study how robot-human interactions can help the astronauts in the space environment. In its first message, Kirobo wished Earth a “good morning” and mentioned (and motioned) its giant step in getting to space.
Kirobo is part of a research project sponsored by the University of Tokoyo and Toyota, and the robot will be working closely with Koichi Wakata, slated to be the first Japanese commander of the ISS for Expedition 39, who will launch this November as part of the Expedition 38/39 crew. An identical robot named Mirata remains on Earth for additional testing.
Kirobo is designed to navigate in zero-gravity, have facial recognition of its fellow crewmates, and will assist Wakata in various experiments. No word on whether it will have access to opening or closing the various hatches on the space station.
Building a flying vehicle for Mars would have significant advantages for exploration of the surface. However, to date, all of our surface exploring vehicles and robotic units on Mars have been terrestrial rovers. The problem with flying on Mars is that the Red Planet doesn’t have much atmosphere to speak of. It is only 1.6% of Earth air density at sea level, give or take. This means conventional aircraft would have to fly very quickly on Mars to stay aloft. Your average Cessna would be in trouble.
But nature may provide an alternative way of looking at this problem.
The fluid regime of any flying (or swimming) animal, machine, etc. can be summarized by something called the Reynolds Number (Re). The Re is equal to the characteristic length x velocity x fluid density, divided by the dynamic viscosity. It is a measure of the ratio of inertial forces to viscous ones. Your average airplane flies at a high Re: lots of inertia relative to air stickiness. Because the Mars air density is low, the only way to get that inertia is to go really fast. However, not all flyers operate at high Re: most flying animals fly at much lower Re. Insects, in particular, operate at quite small Reynolds numbers (relatively speaking). In fact, some insects are so small that they swim through the air, rather than fly. So, if we scale up a bug-like critter or small bird just a bit, we might get something that can move in the Martian atmosphere without having to go insanely fast.
A potential design of an ‘Entomopter’ from Georgia Tech Research InstituteWe need a system of equations to constrain our little bot. Turns out that’s not too tough. As a rough approximation, we can use Colin Pennycuick’s average flapping frequency equation. Based on the flapping frequency expectations from Pennycuick (2008), flapping frequency varies roughly as body mass to the 3/8 power, gravitational acceleration to the 1/2 power, span to the -23/24 power, wing area to the -1/3 power, and fluid density to the -3/8 power. That’s handy, because we can adjust to match Martian gravity and air density. But we need to know if we are shedding vortices from the wings in a reasonable way. Thankfully, there is a known relationship, there, as well: the Strouhal number. Str (in this case) is flapping amplitude x flapping frequency divided by velocity. In cruising flight, it turns out to be pretty constrained.
Our bot should, therefore, end up with a Str between 0.2 and 0.4, while matching the Pennycuick equation. And then, finally, we need to get a Reynolds number in the range for a large living flying insect (tiny insects fly in a strange regime where much of propulsion is drag-based, so we will ignore them for now). Hawkmoths are well studied, so we have their Re range for a variety of speeds. Depending on speed, it ranges from about 3,500 to about 15,000. So somewhere in that ballpark will do.
There are a few ways of solving the system. The elegant way is to generate the curves and look for the intersection points, but a fast and easy method is to punch it into a matrix program and solve iteratively. I won’t give all the possible options, but here’s one that worked out pretty well to give an idea:
Mass: 500 grams
Span: 1 meter
Wing Aspect Ratio: 8.0
This gives an Str of 0.31 (right on the money) and Re of 13,900 (decent) at a lift coefficient of 0.5 (which is reasonable for cruising). To give an idea, this bot would have roughly bird-like proportions (similar to a duck), albeit a bit on the light side (not tough with good synthetic materials). It would, however, flap through a greater arc at higher frequency than a bird here on Earth, so it would look a bit like a giant moth at distance to our Earth-trained eyes. As an added bonus, because this bot is flying in a moth-ish Reynolds Regime, it is plausible that it might be able to jump to the very high lift coefficients of insects for brief periods using unsteady dynamics. At a CL of 4.0 (which has been measured for small bats and flycatchers, as well as some large bees), the stall speed is only 19.24 m/s. Max CL is most useful for landing and launching. So: can we launch our bot at 19.24 m/s?
For fun, let’s assume our bird/bug bot also launches like an animal. Animals don’t take off like airplanes; they use a ballistic initiation by pushing from the substrate. Now, insects and birds use walking limbs for this, but bats (and probably pterosaurs) use the wings to double as pushing systems. If we made our bots wings push-worthy, then we can use the same motor to launch as to fly, and it turns out that not much push is required. Thanks to the low Mars gravity, even a little leap goes a long way, and the wings can already beat near 19.24 m/s as it is. So just a little hop will do it. If we’re feeling fancy, we can put a bit more punch on it, and that’ll get out of craters, etc. Either way, our bot only needs to be about 4% as efficient a leaper as good biological jumpers to make it up to speed.
These numbers, of course, are just a rough illustration. There are many reasons that space programs have not yet launched robots of this type. Problems with deployment, power supply, and maintenance would make these systems very challenging to use effectively, but it may not be altogether impossible. Perhaps someday our rovers will deploy duck-sized moth bots for better reconnaissance on other worlds.
Artist concept of a 5 kg CubeSat with CubeSat Ambipolar Thruster (CAT) firing in low Earth orbit. Via Kickstarter.
Cubesats are all the rage these days: they’re usually inexpensive and quick to build and they can tag along on launches already scheduled for other things. We think of cubesats as being almost “disposable” satellites – tiny spacecraft that go into Earth orbit for a short time, do their science and then burn up harmlessly in Earth’s atmosphere. But a team of scientists have a more long-term, long-distance plan for their cubesats. Benjamin Longmier and James Cutler from the University of Michigan want to build cubesats that have tiny plasma thruster engines that could propel them into deep space, maybe even interstellar space.
They have a vision of their plasma-thruster cubesat waving as it speeds past the Voyager spacecraft at the edge of our Solar System.
They are working on what they call the CubeSat Ambipolar Thruster (CAT), a new plasma propulsion system. This thruster technology doesn’t exist all in one piece yet, but Longmeir and Cutler said they could put it together in months, with just a little funding. The CAT plasma thruster will propel a 5kg satellite into deep space, far beyond Earth orbit, at 1/1000th the cost of previous missions.
They’ve begun a $200,000 Kickstarter campaign to help fund their project. Their ideas of what these thruster propelled cubesats could do are mind-bogglingly exciting: flying through the plumes of Enceladus to look for life, studying and tagging asteroids, formation flying through Earth’s magnetosphere to learn more about solar flares and the aurora or just an interplanetary message in a bottle lasting for hundreds of millions of years in orbit around the Sun.
They think they can get a satellite up and flying within 18 months.
“The traditional funding process starts with some seed data, a large government grant and a large number of milestones and gates to go through,” said Longmier in a press release from the University of Michigan. “We’d like to leverage Kickstarter funds to compress that timeline and go from initial seed data to flight in about 18 months, a much faster time scale than is possible with traditional grants.”
The cubesats would be about as big as a loaf of bread and the thrusters – the first of its kind — would use superheated plasma directed through a magnetic field to propel the CubeSat. The duo says that with this technology, exploring interplanetary space and eventually other planets would become faster and cheaper than ever before.
While plasma rockets have been used before, they’ve only been used on big spacecraft like Deep Space 1 and DAWN. Longmier and Cutler are miniaturizing the system. Most of the thruster components have been built and have been tested individually, but they need help through Kickstarter to assemble everything into one compact thruster unit for testing the integrated components in the lab, then in Earth orbit, and then interplanetary space.
They’ve got more info on how the thrusters work on their Kickstarter page.
A near-infrared view of NGC 4038 (one of the Antenna Galaxies) obtained with the Gemini Observatory's new adaptive optics system. Credit: Image data from Rodrigo Carrasco, GeMS System Verification Team, Gemini Observatory. Color composite image by Travis Rector, University of Alaska Anchorage.
Rise above Earth with a telescope, and one huge obstacle to astronomy is removed: the atmosphere. We love breathing that oxygen-nitrogen mix, but it’s sure not fun to peer through it. Ground-based telescopes have to deal with air turbulence and other side effects of the air we need to breathe.
Enter adaptive optics — laser-based systems that can track the distortions in the air and tell computers in powerful telescopes how to flex their mirrors. That sparkling picture above came due to a new system at the Gemini South telescope in Chile.
It’s one of only a handful pictures released, but astronomers are already rolling out the superlatives.
“GeMS sets the new cool in adaptive optics,” stated Tim Davidge, an astronomer at Canada’s Dominion Astrophysical Observatory.
The planetary nebula NGC 2346. Credit: Gemini Observatory/AURA (Image data from Letizia Stanghellini, National Optical Astronomy Observatory, Tucson, Arizona. Color composite image by Travis Rector, University of Alaska Anchorage.)
“It opens up all sorts of exciting science possibilities for Gemini, while also demonstrating technology that is essential for the next generation of ground-based mega-telescopes. With GeMS we are entering a radically new, and awesome, era for ground-based optical astronomy.”
Other telescopes have adaptive optics, but the Gemini Multi-Conjugate Adaptive Optics System (GEMS) has some changes to what’s already used.
It uses a technique called “multi-conjugate adaptive optics”. This increases the possible size of sky swaths the telescope can image, while also giving a sharp view across the entire field. According to the observatory, the new system makes Gemini’s eight-meter mirror 10 to 20 times more efficient.
The Gemini South telescope during laser operations with GeMS/GSAOI. Credit: Manuel Paredes
The next step will be seeing what kind of science Gemini can produce from the ground with this laser system. Some possible directions include supernova research, star populations in galaxies outside of the Milky Way, and studying more detail in planetary nebulae — the remnants of low- and medium-mass star.
