What’s the Best Design for a Flying Mars Robot?

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 Institute
A potential design of an ‘Entomopter’ from Georgia Tech Research Institute
We 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.

Solar Powered Plane Soars Over the Golden Gate Bridge

The world’s first solar-powered plane is stretching its wings over the US. Today it took off from Moffett Field in Mountain View, California — the home of NASA’s Ames Research Center – and flew to San Fransisco, soaring over the Golden Gate Bridge.

Starting on May 1, Solar Impulse will fly across the US to New York, making several stops along the way as a kind of “get to know you” tour for the US while the founders of Solar Impulse, Swiss pilot Bertrand Piccard and and pilot Andre Borschberg, want to spread their message of sustainability and technology. You can read about the cross-country tour here on UT and also on the Solar Impulse website. You can follow Solar Impulse’s Twitter feed for the latest news of where they are.

Scientist Invents a Time Machine (*Wink*)

An interesting news item from Iran’s Entkhab news agency: Iranian scientist Ali Razeghi – who is also the managing director of Iran’s Center for Strategic Inventions — has registered a new invention of his own making: a time machine.

It’s doesn’t actually take anyone to the past or future, but produces printed reports with details about the future, and can “predict five to eight years of the future life of any individual, with 98 percent accuracy” according to Razeghi, as quoted in The Telegraph.

“My invention easily fits into the size of a personal computer case and can predict details of the next 5-8 years of the life of its users,” he says. It will not take you into the future, it will bring the future to you.”

Razeghi, 27, says he has been working the project for 10 years and this is the 179th invention he has registered.

The “time machine” would be a good resource for governments, he said, but he doesn’t want to launch a prototype at this point because “the Chinese will steal the idea and produce it in millions overnight.”

Razeghi said his latest project has been criticized by friends for “trying to play God” with ordinary lives and history. “This project is not against our religious values at all,” Razaghi was quoted. “The Americans are trying to make this invention by spending millions of dollars on it where I have already achieved it by a fraction of the cost.”

Of course, this has spurred articles about Doc Brown and DeLoreans, with hardly anyone taking this seriously.

New Meme Puts Space Robots in Their Place

Oh, those space robots. They don’t always do what we want them to do, but we love them anyway. If you need a fun diversion in your day, a new Tumblr site has arisen to call out the robots who have made mistakes. Called “Shaming Robots” it started innocently with an image posted of the engineering model of the Curiosity rover blaming the engineering Opportunity rover for messing up JPL’s Mars Yard. There’s now pages of shamed robots (both space and Earth-based). Submit your own if you have a robot you’d like to shame. You can also follow the fun discussion on Twitter at the hashtag #robotshaming.

Astronomer Alex Parker stared the 'Robot Shaming' meme with this image of the engineering model of Curiosity at JPL.
Astronomer Alex Parker stared the ‘Robot Shaming’ meme with this image of the engineering model of Curiosity at JPL.

Solar Powered Plane to Fly Across the US

On May 1, the world’s first solar-powered plane will take off from Moffett Field in Mountain View, California — the home of NASA’s Ames Research Center – and fly across the US to New York. Even though the Solar Impulse plane could probably fly non-stop, day and night with no fuel, instead it will make several stops in US cities such as Phoenix, Dallas, and Washington, D.C. This would be a kind of “get to know you” tour for the US while the founders of Solar Impulse, Swiss pilot Bertrand Piccard and and pilot Andre Borschberg, want to spread their message of sustainability and technology.

“It carries one pilot and zero passengers, but it carries a lot of messages,” Piccard said during a press briefing yesterday. “We want to inspire as many people as possible to have that same spirit: to dare, to innovate, to invent.”

The solar plane made its first intercontinental flight from Spain to Morocco last June, flew continuously through the night in 2010, and by 2015 they hope to fly a similar aircraft around the world.

The Solar Impulse HB-SIA has 12,000 solar cells built into its 64.3-meter (193-foot) wings. That’s longer than an entire Boeing 747 airplane but it weighs just 1,600 kg (3,500 lb), less than a car. It is powered by four electric motors.

Originally built only to prove the possibility of flying day and night, their goal for future flights is to fly for up to five days and five nights, all by one pilot. Such a feat has never been accomplished.

They are using meditation and hypnosis (Bertrand is a psychologist who uses hypnosis) to train the pilots as they prepare to fly on very little sleep, Borschberg said. He added that they are working on an autopilot system would have to be built on the next plane to allow for some rest.

The first stop for the Solar Impulse as it crosses the United States will be Phoenix, followed by Dallas and then one of three cities: Atlanta, Nashville or St. Louis. It will then stop outside Washington D.C. before heading on to New York.

The Solar Impulse team said the stopovers will be a great occasion to spread Solar Impulse’s message meant to inspire people. “Only by challenging common certitudes can there be change and, through conferences on educational themes, Solar Impulse wishes to motivate everybody to become a pioneer in the search for innovative solutions for society’s biggest challenges,” the team said.

You can check on the planned stopovers at the Solar Impulse website.

White House Petition: Could we Build the Starship Enterprise?

Could we build a version of the Starship Enterprise over the next 20 years? Credit: BuildTheEnterprise.org

Earlier this year, an engineer who goes by the name of BTE Dan proposed building a full-sized, ion-powered version of a Constitution-Class Enterprise – from the original Star Trek – saying it could be built with current technology and could be completed within 20 years. Now, BTE Dan has started a White House petition — not to build the Enterprise but to just do a feasibility study and conceptual design of the USS Enterprise interplanetary spaceship. As of this writing, the petition has 1,414 signatures of the 25,000 needed by January 21, 2013 to be considered by the Obama administration.

The petition reads:

We have within our technological reach the ability to build the 1st generation of the USS Enterprise. It ends up that this ship’s inspiring form is quite functional. This will be Earth’s first gigawatt-class interplanetary spaceship with artificial gravity. The ship can serve as a spaceship, space station, and space port all in one. In total, one thousand crew members & visitors can be on board at once. Few things could collectively inspire people on Earth more than seeing the Enterprise being built in space. And the ship could go on amazing missions, like taking the first humans to Mars while taking along a large load of base-building equipment for constructing the first permanent base there.

See the petition and sign it here.

BTE Dan told Universe Today earlier this year that what he really is hoping for is to find a segment of scientists and engineers in the space industry to take an active interest and contribute to the ideas on his website, BuildTheEnterprise.org to help move the concept forward.

“I have been getting many offers of help from engineers outside the space industry, and that’s great,” he said via email. “But also what is needed are some experienced space engineers who adopt a can-do attitude about the concept of the Gen1 Enterprise.”

BTE Dan prefers to remain anonymous at this point, and his biggest concern has been that the scientists and engineers at NASA and their space contractors were going to be hostile about the idea, as his first brush with them did not go well.

Diagram of a proposed current generation of a Starship Enterprise. Credit: BuildTheEnterprise.org

“I am an outsider poking around in their sandbox, and human nature is that people don’t like that,” he said, noting that he knows his design may have fatal flaws, but that is why he is looking for assistance.

“There is a lot of waste heat to get rid of, today’s ion propulsions engines need major advances, and perhaps stability problems will be found with the gravity wheel,” he said.

When Universe Today broke the story of the BuildTheEnterprise concept in May of this year, it went viral and BTE Dan’s website crashed under the traffic.

“I really did not expect this at all,” he said at the time. “I did not plan for this level of web traffic!” He has since made upgrades to handle more traffic.

His website is complete with conceptual designs, ship specs, a funding schedule, and almost every other imaginable detail of how the Enterprise could be built. It would be built entirely in space, have a rotating gravity section inside of the saucer, and be similar in size with the same look as the USS Enterprise that we know from Star Trek.

The White House takes petitions on many topics at the “We the People” website and will consider them if they receive 25,000 signatures. Earlier this year, a petition to build a Death Star space station by 2016 received over 32,000 signatures, but so far there has not been an official response about it from the White House.

NASA’s Version of Mr. Fusion

Researcher Stephen Anthony works with the new reactor prototype that could turn trash into gas. Image credit: NASA/Dmitri Gerondidakis

It probably won’t be able to fuel Doc Brown’s flux capacitor on his DeLorean time machine, but NASA researchers are hoping a new device that will be tested on the International Space Station can turn trash into power. The Trash to Gas Reactor is a miniature version of large waste incineration facilities on Earth that generate electricity or fuel. This could help with the accumulating trash on the ISS and be used on future missions beyond Earth orbit, as well as help the trash problem in areas of the world where there are neither large power plants nor garbage processing facilities.

“Not only will the effort on this help space missions but also on Earth because we have enough problems dealing with our own trash,” said Anne Caraccio, a chemical engineer working on the project.

The prototype of the Trash to Gas Reactor is a meter-long (3 foot-long) device that looks strikingly similar to the “Mr. Fusion” reactor in the second “Back to the Future” movie. Just like Doc Brown and Marty, astronauts can throw in things like food wrappers, used clothing, food scraps, tape, packaging and other garbage accumulated by the crew and the reactor will turn it into potential power, such as methane gas, or even oxygen or water.

The team developing the reactor is hoping to have their prototype ready to fly on the ISS by 2018 – which unfortunately doesn’t fit into the “Back to the Future” timeline: Emmett Brown travels to 2015 where he gets his Mr. Fusion and changes the future. But perhaps its Earth-bound counterpart could be ready in two years, in time for the Doc’s arrival from 1985.

“Back to the Future’s” Mr. Fusion. Via Theme Park Review.

OK, back to reality now, even though this does have a science fiction element to it…

A team led by Paul Hintze at the Kennedy Space Center has built an 80-pound small reactor to test theories about incinerating a variety of trash ranging from used clothes to uneaten food. The reactor holds more than three quarts of material and burns at about 1,000 degrees F, about twice the maximum temperature of an average household oven. It’s expected to take astronauts four hours to burn a day’s worth of trash from a crew of four.

The team estimates that during the course of a year in space – one half the length of time a mission to Mars is expected to take – trash processing for a crew of four would create about 2,200 pounds of methane fuel, enough to power a launch from the lunar surface, Hintze said.

“The longer the mission, the more applicable this technology is,” Hintze said. “If you’re just doing a two-week mission, you wouldn’t want to take along something like this because you wouldn’t get anything out of it.”

Converting garbage into fuel also would keep astronauts from turning their cramped space capsule into an orbiting landfill.

Paul Hintze is the researcher leading the trash-to-gas project at NASA’s Kennedy Space Center in Florida. Image credit: NASA/Dmitri Gerondidakis

The experimental version of the reactor is made of steel, but the team expects to employ a different alloy for future versions, something that might be lighter but just as strong in order to withstand the high temperatures needed to break down the materials and destroy potential microbes.

One of the issues the team is working on is making sure that no smell or potential hazardous gases are created as a by-product in the closed environment of the space station or a spacecraft on its way to deep space.

“On Earth, a little bit of an odor is not a problem, but in space a bad smell is a deal breaker,” Hintze said.

Right now trash in the ISS is stuffed into the Progress resupply ship, which burns up in the atmosphere during re-entry. This new reactor could turn the trash into something valuable in space.

Source: NASA

Google Honors Canadarm’s 31st Anniversary

Canada’s most famous robot is on the front page of Google.ca today. The Google doodle honors the 31st anniversary of the first use of Canadarm in space.

Canadarm is a robotic arm that flew on virtually every shuttle mission. The technology is still being used today in space.

According to the 1992 book A Heritage of Excellence, Canada was first invited to work in the shuttle program in 1969. Toronto engineering firm DSMA-Atcon Ltd. initially pitched a Canadian-built space telescope, but NASA was more interested in DSMA’s other work.

“The Goddard Space Flight Center in Maryland expressed interest in another of DSMA’s gadgets – a robot the company had developed for loading fuel into Candu nuclear reactors,” wrote Lydia Dotto in the book, which Spar commissioned to celebrate its 25th anniversary.

“It was just the thing for putting a satellite they were building into space.”

Dozens of astronauts have used the Canadarms during spacewalks, including Michael L. Gernhardt on STS-104. Credit: NASA

The Canadian government and NASA signed a memorandum of understanding in 1975 to build the arm. Legislation allowing the project to move forward passed the next year. Canadian company Spar became the prime contractor, with DSMA, CAE and RCA as subcontractors.

Engineers had to face several challenges when constructing the Canadarm, including how to grapple satellites. The solution was an “end effector“, a snare on the end of the Canadarm to grasp satellites designed to be hoisted into space.

Several NASA astronauts, including Sally Ride, gave feedback on the arm’s development. Canadarm flew for the first time on STS-2, which launched Nov. 12, 1981. (Ride herself used the arm on STS-7 when she became the first American woman to fly in space.)

Marc Garneau, the first Canadian astronaut in space, has said the arm’s success led to the establishment of the Canadian astronaut program. He flew in 1984, three years after Canadarm’s first flight.

Canadian astronaut Chris Hadfield during an EVA in 2001. Also in the image is the Canadarm2 robotic arm on the ISS. Credit: NASA

Some of the arm’s notable achievements:

– Launching space probes, including the Compton Gamma Ray Observatory, as well as short-term experiments that ran during shuttle missions;

– Retrieving satellites for servicing. One prominent example was the rescue of the INTELSAT VI satellite on STS-49, which required the first three-astronaut spacewalk;

Launching the Hubble Space Telescope, then retrieving and relaunching it during each repair mission;

– Helping to build the International Space Station along with Canadarm2, its younger sibling;

– Scanning for broken tiles on the bottom of the shuttle. Astronauts used a procedure developed after Columbia, carrying seven astronauts, was destroyed during re-entry in 2003. A Canadarm was modified into an extension boom; another Canadarm grasped that boom to reach underneath the shuttle.

The arm was so successful that MacDonald, Dettwiler and Associates (which acquired Spar) built a robotic arm for the International Space Station, called Canadarm2. Canadian astronaut Chris Hadfield helped install the arm during his first spacewalk in 2001.

Canadarm2’s most nail-biting moment was in 2007, when astronauts used it to hoist astronaut Steve Parazynski (who was balancing on the extension boom) for a tricky solar panel repair on the station.

November 3, 2007 – Canadarm2 played a big role in helping astronauts fix a torn solar array. Here, Scott Parazynski analyses the solar panel while anchored to the boom. Credit: NASA

More recently, Canadarm2 was used to grapple the Dragon spacecraft when SpaceX’s demonstration and resupply missions arrived at the International Space Station this year.

MDA recently unveiled several next-generation Canadarm prototypes that could, in part, be used to refuel satellites. The Canadian Space Agency funded the projects with $53 million (CDN $53.1 million) in stimulus money. MDA hopes to attract more money to get the arms ready for space.

You can read more about the Canadarm’s history on the Canadian Space Agency website.

The Dust “Windshield Wiper” That Didn’t Go to Mars

A device that works as a windshield wiper to eliminate Mars dust from the sensors on Mars spacecraft. Credit: UC3M

In the past when we’ve discussed how dust accumulates on the solar panels of the Mars Exploration Rovers, Spirit and Opportunity, the most-often posted comments on those articles usually said something like, “They should have developed a windshield-wiper-like device to get rid of the dust!” Our readers will be happy to know such a device has now been invented. A team of researchers created extremely lightweight wipers that could be used to remove dust on Mars spacecraft. In fact, the researchers from Universidad Carlos III in Madrid, Spain developed the device for the Curiosity rover, but unfortunately, it wasn’t used for the MSL mission. But it’s ready to go for future Mars landers and rovers

While Curiosity doesn’t have solar panels, (it instead uses a longer-lasting RTG for power – a Thermoelectric Generator, which is a power system that produce electricity from the natural decay of plutonium-238) it does have sensors that can be affected by the accumulation of dust, such as the meteorological station, the Rover Environmental Monitoring Station (REMS).

The UC3M team created a brush made up of Teflon fibers, designed to clean the ultraviolet sensors on REMS.

“In our laboratories, we demonstrated that it worked correctly in the extreme conditions that it would have to endure on Mars,” said Luis Enrique Moreno, a professor who was head of the project, “with temperatures ranging between zero degrees and eighty below zero Celsius, and an atmospheric pressure one hundred times lower than that of the earth.”

Because weight is an issue when launching objects to other worlds, they used a very lightweight material for the wiper actuators, made from shape memory alloys (SMA), a very light nickel and titanium alloy that allows movement when the composite is heated.

“The main advantage is that these alloys produce a material that is very strong as related to its weight, that is, a thread of less than one millimeter can lift a weight of 4 or 5 kilograms,” said Moreno. “The problem presented by these mechanisms is that, because they are based on thermal effects, they are not as efficient as motor technology, although they are much lighter, which is a very important consideration in space missions.”

This group and other research groups at UC3M are currently working on a second, more elaborate prototype based on SMA technology. It will be used to clean dust from fixed meteorological stations that would be part of the MEIGA-METNET mission, a proposed Mars lander developed by Finnish Meteorological Institute, along with groups from Russia and Spain to do atmospheric observations, but which is not yet part of an official mission yet.

Here’s a look at the proposed unique landing proposed for METNET:

“We are also using this technology to develop the exoskeletons used to aid people with mobility problems, trying to substitute motors with these materials, in order to reduce the devices’ weight and increase agility in their use,” said Moreno, adding that this new product could even be used in the future to improve the joints on the gloves used by astronauts during EVAs.

Source: Universidad Carlos III

Want to Look Inside a Burning Rocket Engine?

Here’s a bit of pretty amazing hobby rocket porn. Ben Krasnow walks us through — in a rather matter-of-fact way — of how he built a hybrid rocket engine in his shop using a piece of acrylic so he could see inside and watch the gaseous oxygen burn. As one commenter on You Tube described it, “Hey guys, I was bored, so I built a transparent rocket engine in my garage. No big deal.”

“This engine is only meant to run for 10 seconds at most,” says Krasnow in his video, “and so this construction isn’t going to last long enough to make a reusable rocket, let’s just say. This is definitely for demo only!”

Next up, Krasnow will travel through time to contact Montgomery Scott to find out how to create transparent aluminum. If seeing this video makes you want to do an impression of Tim the Toolman Taylor, Krasnow also has a video tour of his shop.