Engineers Stumble onto a Whole New Method of Laser-Based Spacecraft Propulsion

As reported by Motherboard: A team of Chinese physicists has developed a new variety of light-based propulsion system with the ability to harness much greater forces than a conventional solar sail. The key, according to the Nankai University-based group, is in swapping out the mirrored sail—which captures photonic energy as radiation pressure in much the same way a regular air-sail captures wind energy—for a pure-black graphene sponge. Rather than reflect off of the sail, light is absorbed by the sponge, which converts that energy into propulsion.

The group's work is published this week in Nature Photonics.

Using light and lasers to move stuff around isn't exactly new. Scientists have trapped, moved, levitated, and pulled all manner of micro and nanoscale objects, including graphene, but also cells, viruses, single molecules, and atoms. Really small stuff.

In one particular form, the concept is known as optical tweezers, which are IRL, not uncommon scientific instruments. The dream, however, is to scale light-based manipulation up to the world of the macroscopic, which is our (visible) world.

"If these optical operations were to be achieved with large objects on a macroscopic spatial scale, significant applications such as the long-sought direct optical manipulation of macroscale objects—including the proposed solar sail and space transportation via laser or beam-powered propulsion—could be realized," the Chinese group, led by civil and environmental engineering professor Yongsheng Chen, writes.

Enter our graphene sponge, which offers just that macroscale manipulation.

The general idea is this. Graphene can absorb light like few if any other known materials, making it indeed a perfect or close-to-perfect photonic "sponge." The result, referred to as "efficient light-induced ejected electron emission" in the paper, is that the electrons within the material get extra excited or energetic and some of them pop right back out of the material. As the electrons bounce away from the graphene, there is a backwards push against it, just as you'd expect from Newtonian mechanics. Every action has a corresponding reaction and, here, that reaction is motion or a transference of momentum. The sponge moves.

Part of the whole problem in engineering something like this is the very basic nature of graphene, which is defined as a two-dimensional lattice of carbon atoms; that is, graphene exists as a perfectly flat, single atom-tall sheet. Stacking sheets of graphene together into "bulk" graphene generally negates many of the material's odd and highly-desirable properties, such as its tremendous mechanical strength—despite being unimaginably thin, the material is bulletproof and many times stronger than steel—and extraordinary electrical and thermal conductivity.

"The force needed for attitude control and orbital adjustment of a spacecraft, and even transporting a payload in outer space could be achieved using light directly."

Yongsheng Chen and his team discovered the light-based propulsive properties of bulk graphene somewhat by accident. "When cutting the graphene sponge by laser in air," the group writes, "we accidentally observed the laser-induced actuation by naked eyes, which contrasts sharply with the earlier reported microscopic levitation or movement of micro objects due to light pressure. To avoid the likely intervention of air, further systematic studies were carried out in vacuum environment entirely to rule out (minimize) the possibility of heated air disturbance and to avoid the local combustion of graphene sponge due to the presence of oxygen."

What followed was a series of experiments using graphene sponges sealed in vertical and horizontal vacuum tubes, where beams of light were applied to the material from either end, causing the material to either levitate or move along the tube laterally. By changing the distance between the light source and the material, the effect could be increased or decreased. The mechanism behind the phenomenon, the ejection of excited electrons, was further verified using x-ray photoelectron spectroscopy to measure the emitted particles.

"It is important to emphasize that the remarkable light-induced macroscale propulsion reported herein is a result of the unique electronic band structure at the Dirac point and associated optoelectronic properties of the graphene sheet itself together with the unique macro structural character of this novel bulk graphene material," the group writes.

The upshot is that the propulsion system should work with other two-dimensional materials in bulk form, such as silicene, germanium, and certain other thin films. This opens the door to practical macroscopic uses of the phenomenon, according to Chen and co.

"While the propulsion energy/force is still smaller compared with conventional chemical rockets, it is already several orders larger than that from light pressure," the researchers conclude. "The propulsion could be further enhanced by increasing the light intensity and/or improving the illumination area. For example, using an adjustable laser array, the force needed for attitude control and orbital adjustment of a spacecraft, and even transporting a payload in outer space could be achieved using light directly."

An open-access version of Chen's paper is available at the arXiv pre-print server.

NASA Completes Third Hot Fire Test of SLS Engine (Video)

As reported by Aerospace Technology.com: Nasa has completed the third hot fire test of an RS-25 engine of the Space Launch System (SLS) at its Stennis Space Center near Bay St Louis, Mississippi, US.

The agency has fired the engine for up to 500 seconds.

SLS is Nasa's new rocket, which is being designed to send astronauts on future missions beyond Earth's orbit at speeds of 17,500 mph. It will be equipped with four RS-25 engines.

Nasa Marshall Space Flight Center SLS liquid engines office manager Steve Wofford said: "While we are using proven space shuttle hardware with these engines, SLS will have different performance requirements.

"That's why we are testing them again. This is a whole new ballgame, we need way more power for these engines to be able to go farther than ever before when it comes to human exploration."

Nasa conducted the first RS-25 test in the series on 9 January, and the second test on 28 May. The agency is preparing to conduct four more tests as part of the current development engine.

"We need way more power for these engines to be able to go farther than ever before when it comes to human exploration."

The tests are designed to demonstrate the performance of the engines with colder liquid oxygen temperatures, greater inlet pressure and higher vehicle acceleration, more nozzle heating, and its position with the SLS booster exhaust nozzles.

During the tests, the new ablative insulation and heaters will also be evaluated.

"We have several objectives that will be accomplished during this test series, which will provide critical data on the new engine controller unit, materials and engine propellant inlet pressure conditions," Wofford added.

Sacramento, California-based Aerojet Rocketdyne serves as the prime contractor for the RS-25 engine program.

Designated Exploration Mission 1, the SLS first test flight will have 77t lift capacity, and will carry an uncrewed Orion spacecraft beyond low-Earth orbit. Going forward, it will be enhanced with lift capability of 143t to facilitate missions even farther into solar system to destinations such as Mars.

Wi-Fi and LTE Join-Up for Gigabit Mobile Services

As reported by CIO: What happens if you combine the best of Wi-Fi and cellular networks? In South Korea, consumers get gigabit-speed service to their phones.

Samsung Electronics and mobile operator KT have developed a hybrid technology called GiGA LTE that can bring LTE and Wi-Fi signals together for download speeds as high as 1.17Gbps (bits per second), according to The Korea Herald. GiGA LTE is available now with a firmware upgrade to Samsung Galaxy S6 and S6 Edge handsets.

Wi-Fi and LTE are becoming wary neighbors as cellular operators look for more spectrum and all types of wireless networks face growing user demands. Carriers are looking into LTE-Unlicensed, which can transmit LTE signals in the same band with Wi-Fi, and Qualcomm is now exploring a technology that would let more types of operators set up those networks. Some Wi-Fi backers say LTE-Unlicensed could squeeze out wireless LAN users.

GiGA LTE uses KT’s own network of Wi-Fi hotspots, of which there are about 140,000 around South Korea, along with its approximately 200,000 LTE base stations, The Korea Herald said. KT plans to gradually increase the coverage area of the fast hybrid network and make it available on more phones: It will be available for five or six more Samsung models and some LG Electronics phones in the second half of the year.

The gigabit-plus throughput that GiGA LTE can achieve is four times faster than the fastest LTE service in the Korea, which uses LTE-Advanced features to combine three frequency bands and is already among the world’s fastest.

Alcatel-Lucent introduced a system earlier this year, called Wi-Fi boost, that uses a cellular connection just for upstream traffic and Wi-Fi strictly for downloads. It could provide up to a 70 percent increase in download speed and an order of magnitude faster uplinks, the company said. It plans to start selling Wi-Fi boost in the second half of this year. A later version will allow the two networks to combine their download signals, Alcatel said.

Rival carrier SK Telecom also plans to commercialize hybrid Wi-Fi and LTE network technologies this month with partner LG Electronics, The Korea Herald said.

A New iPhone Feature Can Save Children's Lives

As reported by HuffPost Tech: Approximately 40 children die each year from heat stroke after being left in cars by distracted, absentminded or careless parents. And that is in the U.S. alone. A minor update to Apple's smartphone operating system could help to prevent these accidents from happening in the future.

iPhone users have long been able to set reminders based on particular locations. For example, you can tell your iPhone: 'Open a bottle of wine when I get home,' and if you've previously told your iPhone where you live it will use the 'geofence' around your house to know when you get in and prompt you with the reminder. Apple spent just a few seconds at its latest event showing off geofences for your car.

If you have CarPlay (Apple's solution for safely using an iPhone in the vehicle) your car will now be recognized as a location and you'll be able to set reminders based on entering or exiting your vehicle.

From here the solution is simple: Set a reminder such as "Siri, remind me every day when I get out of the car: check for kids!" And a reminder will appear as you walk away from the car, replacing possible catastrophe with slight embarrassment. Do I want to admit to myself that it's possible to forget my kids in the car? Probably, not. But is it possible? The facts are indisputable: yes, it is. And I would rather admit it and take practical steps to prevent it, than deny it and avoid those steps.

Several companies including Intel, BabyAlert and others are developing innovative preventive measures such as microchips and sensors installed inside car seats to reduce these accidental deaths.

Smartphone reminders may not replace these entirely, and nothing can negate the need for attentive and careful parenting, but a simple reminder to make sure you've left no one behind could be one piece in saving a child's life.

It's Official: SpaceX Is Building Elon Musk's Hyperloop

As reported by Motherboard: SpaceX is building a hyperloop, Elon Musk's fantastical, futuristic transport tube capable of moving people and freight at speeds of 760 miles per hour.

The company is building a one- to three-mile-long hyperloop test track outside its Hawthorne, California headquarters with plans to test the technology within a year, according to documents obtained by Motherboard (embedded below). It's the first time that Musk, who conceived of the hyperloop, has been involved with any concrete plans to actually build it.

"SpaceX will be constructing a sub-scale test track (inner diameter between 4 and 5 feet; length approximately 1 mile) adjacent to its Hawthorne, California headquarters)," an official SpaceX document, called "SpaceX Hyperloop Pod Competition," said. "In order to accelerate the development of a functional prototype and to encourage student innovation, SpaceX is moving forward with a competition to design and build a half-scale Hyperloop pod."

"In addition to hosting the competition, SpaceX will likely build a pod for demonstration purposes only," the document said.

Musk offhandedly mentioned that he was working on a "fifth mode of transportation" in the summer of 2012, but said he didn't have the time necessary to work on it, with SpaceX, Tesla Motors, and SolarCity taking up the bulk of his time. But the public reaction to the hyperloop was so positive that, in August 2013, he and some SpaceX engineers drew up a highly detailed white paper describing a hyperloop that would shuttle passengers and cargo between Los Angeles and San Francisco in 35 minutes.

"We are interested in helping to accelerate development of a functional hyperloop prototype"

After Musk released the white paper, he made no indication that SpaceX or any other of his companies was actually working on the fantastical hyperloop. Instead, the paper, plans, and design were open sourced so that any company or engineer could work on the design.

Two companies, Hyperloop Transportation Technologies and Hyperloop Technologies, have started work on commercial hyperloops; Hyperloop Transportation Technologies announced last month that it is planning to build a five-mile test track in California. Neither Musk nor SpaceX has anything to do with those companies, and the SpaceX test track will be the first official project he's been involved with.


The hyperloop would consist of a steel, partially pressurized tube and various "pods" or "capsules" that can carry people, freight, and potentially cars.

“Just as aircraft climb to high altitudes to travel through less dense air, Hyperloop encloses the capsules in a reduced pressure tube,” Musk wrote in the white paper. “The pressure of air in the Hyperloop is about ⅙ the pressure of the atmosphere on Mars … a hard vacuum is avoided as vacuums are expensive and difficult to maintain compared with low pressure solutions.”

Motors on the pods themselves would create a cushion of air that would allow the pods to float within the tube, and they would be pushed along the tube by linear induction motors positioned along the inside of the tubes. These tubes would be powered by solar panels mounted on their outer surface.

Musk has said that for cities less than 900 miles apart, the hyperloop would be faster and cheaper than air travel and better than existing trains in just about every way. It would travel at just under the speed of sound, for passenger comfort and safety.

According to the company, SpaceX has no plans to actually build a commercial hyperloop like the one proposed in the white paper. Instead, the company is trying to spur innovation and attention to the design, and it wants to prove that the concept actually works. SpaceX told me that it's happy two companies are actually trying to design and build commercial hyperloops, and that the company does not want to compete with them. SpaceX's primary focus is still on spaceflight and on eventually sending humans to Mars.

"We are excited that a handful of private companies have chosen to pursue this effort," the company said. "While we are not developing a commercial hyperloop ourselves, we are interested in helping to accelerate development of a functional hyperloop prototype."

In the contest, teams of university students will be tasked with designing passenger pods and presenting them at a meet up with SpaceX officials at Texas A&M University in January, 2016. The best designs will actually be built at half scale and will be tested in June of 2016 at the SpaceX hyperloop test track. These pods will apparently be large enough to put a human inside, but will be tested without passengers.

In the white paper, Musk showed what a pod might look like:





SpaceX says it will release more information about the contest, such as technical details, in August. For now, you can check out the document announcing the contest below.

Spacex Hyperloop Pod Competition

Uber is Using GPS to Punish Drivers in China Who Get Too Close to Protests

As reported by Fusion: Uber is using GPS on drivers’ phones to identify, and threaten, drivers loitering by taxi protests in China, the Wall Street Journal reports.

For months, there’s been tension in the country between ride-share companies and taxi drivers, who fear the new companies will make it even harder for them to make a living. Bloomberg View’s Adam Minter pointed out the severity of the situation:

“Drivers have not hesitated to disrupt the public’s daily life. In January, when drivers in at least six major cities decided to strike, they didn’t just stop working; they blocked traffic, and even besieged private cars associated with taxi hailing apps. In at least one instance, riot police were forced to intervene.”

That anger has prompted China to come down especially hard on Uber, says Minter:

“China’s crackdown on Uber, in other words, may have less to do with protecting the owners of politically powerful taxi services than placating the taxi industry’s increasingly volatile labor force.”

So Uber’s been in a shaky place, both with the government and with the taxi-driving community, for a long time now. But the incident that prompted Uber to explicitly warn drivers away from participating in protests, however, happened on Friday. On that day, a local official in Guangzhou reportedly hailed a car driven by one of Uber’s ride-share competitors, Didi Kuaidi. The official tried to arrest the driver, and set another major protest in motion. Quartz describes the scene:

“Dozens of Didi Kuaidi drivers who apparently caught news of the attempted sting surrounded the vehicle, waving signs in support of Didi and demanding the official, who was inside the car, let the driver off the hook. The mass of supporters blocked traffic, and police arrived to break up the crowds, photos posted on Sina Weibo (log-in required) show.”

The next day, Uber told its drivers to keep away from such protests. The Financial Times reports that Uber drivers in Hangzhou received a message imploring them: “Please don’t wreck the good urban environment you have all worked so hard to help build… If you are at the scene, leave immediately.”

More damningly, the message added that there would be consequences for those who didn’t follow instructions, and that Uber would track drivers’ GPS devices (i.e., personal phones) to make sure they comply. These measures, reports the WSJ, are intended to “maintain social order.” Not something you want to hear from an employer.

An Uber spokesperson in Beijing told Quartz that “we firmly oppose any form of gathering or protest, and we encourage a more rational form of communication for solving problems.”

It makes sense for Uber to tread lightly in China, where it is reportedly planning a rapid expansion, with a price tag of more than one billion dollars. Maybe Uber should spend some of that money figuring out how to deal with its (many) privacy issues, first.

Uber did not respond to requests for comment.

China Confirms Test of Hypersonic Glide Vehicle

As reported by Yibada: The People’s Liberation Army (PLA) has confirmed reports that it has conducted a fourth test of China's ultra-high-speed hypersonic glide vehicle for nuclear delivery called the WU-14, Bill Gertz, senior editor of the Washington Free Beacon, wrote in an article published on June 11.

According to the article, China conducted the test on June 7, which was the fourth in the series of tests on the WU-14 in the past 18 months.

The WU-14 was believed to be on PLA's high-priority list for development, the U.S. intelligence said.

The first WU-14 test reportedly took place on Jan. 9, 2014, followed by two more tests on Aug. 7 and Dec. 2. The report said that all four tests have been conducted at the same facility in western China.

The article quoted a U.S. intelligence official as saying that the latest test showed the WU-14's ability and "extreme maneuvers" to penetrate U.S. missile defense systems, for the first time.

The official said that the WU-14 was allegedly designed to neutralize U.S. strategic missile defenses and has the unique capability to fly at ultra-high speeds and maneuver to avoid detection and tracking by radar and missile defense interceptors.The Missile Defense Agency of the Pentagon, however, refused to make any comment on the development of the WU-14, although a U.S. congressional report published in November last year said that China's hypersonic glide vehicles cannot only make U.S. missile defense system less effective but also render it obsolete.

Gertz said that in addition to the WU-14, the Chinese government is also developing a second hypersonic weapon using scramjet engine technology.