When you look back on the development history of any technology, it’s clear that the successful products eventually reach an inflection point, the boundary between when it was a niche product and when it seems everyone has one. Take 3D-printers, for instance; for years you needed to build one if you wanted one, but now you can buy them in the grocery store.
It seems like we might be getting closer to the day when satellites reach a similar inflection point. What was once the province of nations with deep pockets and military muscles to flex has become far more approachable to those of more modest means. While launching satellites is still prohibitive and will probably remain so for years to come, building them has come way, way down the curve lately, such that amateur radio operators have constellations of satellites at their disposal, small companies are looking seriously at what satellites can offer, and even STEM programs are starting to get students involved in satellite engineering.
Michael Bretti is on the leading edge of the trend toward making satellites more DIY friendly. He formed Applied Ion Systems to address one of the main problems nano-satellites face: propulsion. He is currently working on a range of open-source plasma thrusters for PocketQube satellites, a format that’s an eighth the size of the popular CubeSat format. His solid-fuel electric thrusters are intended to help these diminutive satellites keep station and stay in orbit longer than their propulsion-less cousins. And if all goes well, someday you’ll be able to buy them off-the-shelf.
Join us for the Hack Chat as Michael discusses the design of plasma thrusters, the details of his latest testing, and the challenges of creating something that needs to work in space.
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Spaceflight is inherently dangerous. It takes a certain type of person to willingly strap into what’s essentially a refined bomb and hope for the best. But what might not be so obvious is that the risks involved aren’t limited to those who are personally making the trip. The construction and testing of space-bound vehicles poses just as much danger to engineers here on the ground as it does to the astronauts in orbit. Arguably, more so. Far more individuals have given their lives developing rocket technology than have ever died in the cockpit of one of them.
Ultimately, this is because of the enormous amount of energy stored in the propellants required to make a rocket fly. Ground support personnel need to exercise great care even when dealing with “safe” propellants, such as the classic combination of kerosene and liquid oxygen. On the other end of the spectrum you have chemicals that are so unstable and toxic that they can’t be handled without special training and equipment.
One of the most dangerous chemicals ever used in rocket propulsion is hydrazine; and yet from the Second World War to the present day, it’s been considered something of an occupational hazard of spaceflight. While American launch vehicles largely moved away from using it as a primary propellant, hydrazine is still commonly used for smaller thrusters on spacecraft.
But soon, that might change. NASA has been working on a project they call the Green Propellant Infusion Mission (GPIM) which is specifically designed to reduce modern spacecraft’s dependency on hydrazine. In collaboration with the Air Force Research Laboratory at California’s Edwards Air Force Base, the space agency has spearheaded the development of a new propellant that promises to not just replace hydrazine, but in some scenarios even outperform it.
So what’s so good about this new wonder fuel, called AF-M315E? To really understand why NASA is so eager to power future craft with something new, we first have to look at the situation we’re in currently.
The Kepler spacecraft is in the final moments of its life. NASA isn’t quite sure when they’ll say their last goodbye to the space telescope which has confirmed the existence of thousands of exoplanets since its launch in 2009, but most estimates give it a few months at best. The prognosis is simple: she’s out of gas. Without propellant for its thrusters, Kepler can’t orient itself, and that means it can’t point its antenna to Earth to communicate.
Now far as spacecraft failures go, propellant depletion isn’t exactly unexpected. After all, it can’t pull into the nearest service station to top off the tanks. What makes the fact that Kepler will finally have to cease operations for such a mundane reason interesting is that the roughly $600 million dollar space telescope has already “died” once before. Back in 2013, NASA announced Kepler was irreparably damaged following a series of critical system failures that had started the previous year.
But thanks to what was perhaps some of the best last-ditch effort hacking NASA has done since they brought the crew of Apollo 13 home safely, a novel way of getting the spacecraft back under control was implemented. While it was never quite the same, Kepler was able to continue on with modified mission parameters and to date has delivered so much raw data that scientists will be analyzing it for years to come. Not bad for a dead bird.
Before Kepler goes dark for good, let’s take a look at how NASA managed to resurrect this planet hunting space telescope and greatly expand our knowledge of the planets in our galaxy.
If you’re like us, a body of water is a source of wonder and awe. The wonder comes from imagining what lies hidden below the surface, and the awe is from the fear of trying to find out and becoming one of those submerged objects on a permanent basis. So if you want to explore the depths in relative comfort and safety, a DIY remotely operated underwater vehicle might be the thing you need to build.
Most ROV builds these days seem to follow more or less similar designs, which is probably because they all share project goals similar to those of [dcolemans]: build something to take a look around under the water, make it easy to operate, and don’t spend a ton of money. To achieve that, he used 1/2″ PVC pipe and fittings to build the frame and painted it yellow for visibility. A dry tube for the electronics was fashioned from 4″ ABS pipe. The positive buoyancy provided by the dry tube is almost canceled out by the water flooding the frame through weep holes and the lead shot ballast stored in the landing skids. Propulsion is provided by bilge pump cartridges with 3D-printed ducted propellers. A nice touch is a separate topside control box with a screen for the ROV’s camera that talks to a regular RC controller, along with simplified controls and automatic station keeping. Check out the recent swimming pool test in the video below.
Yes, we’ll come right out and say it – it’s a giant fan, and it blows. Or more accurately, it’s four moderately sized fans in one fetching wrist-mounted package. The one thing that seems completely absent from the video is an answer to the obvious question – why? Other than doing damage to the hearing of anyone nearby in an enclosed space, [Ivan] demonstrates its use with the help of a skateboard in the back end of the video.
It’s built with off-the-shelf RC parts and the body is 3D printed. This is the kind of print you want to get right first time – it takes several days to print and uses a significant amount of filament.
Most of us will have spent the idle hours of our youth while sitting in a room where a teacher was standing at the blackboard explaining iambic pentameter or the Diet of Wurms, daydreaming about the amazing exploits we could have created if only we had an Evil Lair stuffed with all the tools our fertile imaginations demanded. [James Bond] would have had nothing on us, our personal [Q] branch would have ensured we would have had the coolest gadgets on the planet.
As grown-ups we have some of the resources to make this a reality, yet somehow we’ve never made good on the dream. We spend our time creating IoT clocks or novelty electronic Christmas ornaments, and Mr. [Bond] still has a monopoly on the really cool stuff. Fortunately [PeterSripol] has struck a blow on our behalf, because he’s created a pair of arm-mounted underwater thrusters (YouTube, embedded below) that should leave  feeling definitely a bit [006.5].
The thrusters themselves came from a Kickstarter purchase that he left on the shelf for a while without an application. Then with only a short time before a trip to Hawaii, he set to work to do something with them, and the arm thrusters were the result.
He makes extensive use of components from the world of radio controlled models, with battery packs and speed controllers mounted in a waterproof food container at his belt, and a pair of handheld microswitch controllers. There is an Arduino which presumably produces the PWM signal, and we are treated to an in-depth look at his waterproofing efforts for the various connectors and switches. After a false start with battery polarity and a cracked impeller housing the device works, and we see it in use on a suitably tropical though not quite sun-kissed beach.
The thrusters appear to work very well, and we’d say they look a lot of fun to use. Sadly the exercise is brought to a halt when a control wire is sucked into a propeller, but we’re sure that’s only a minor setback. We’ve posted the video below the break, take a look.
There is a device under test out there that promises to take humans to another star in a single lifetime. It means vacations on the moon, retiring at Saturn, and hovercars. If it turns out to be real, it’s the greatest invention of the 21st century. If not, it will be relegated to the history of terrible science right underneath the cold fusion fiasco. It is the EM drive, the electromagnetic drive, a reactionless thruster that operates only on RF energy. It supposedly violates the laws of conservation of momentum, but multiple independent lab tests have shown that it produces thrust. What’s the real story? That’s a little more complicated.
The EM Drive is a device that turns RF energy — radio waves — directly into thrust. This has obvious applications for spacecraft, enabling vacations on Mars, manned explorations of Saturn, and serious consideration of human colonization of other solar systems. The EM drive, if proven successful, would be one of the greatest inventions of all time. Despite the amazing amount of innovation the EM drive would enable, it’s actually a fairly simple device, and something that can be built out of a few copper sheets.