Plasma Resonance Could Overcome Radio Silence for Returning Spacecraft

As reported by GizMag: Returning spacecraft hit the atmosphere at over five times the speed of sound, generating a sheath of superheated ionized plasma that blocks radio communications during the critical minutes of reentry. It's a problem that's vexed space agencies for decades, but researchers at China's Harbin Institute of Technology are developing a new method of piercing the plasma and maintaining communications.

According to physicists Xiaotian Gao and Binhao Jiang of the Habin Institute, by redesigning the spacecraft antenna, it may be possible to maintain communications by setting up resonance in the plasma sheath. Essentially, this involves turning the layer between the spacecraft and the sheath into a capacitor in the antenna circuit. This causes the sheath to act as an inductor. Together, they create a resonant circuit.  

"Once the resonance is reached, the energy can be exchanged between them steadily and losslessly, like real capacitance and inductance do in a circuit," says Gao. "As a result, the electromagnetic radiation can propagate through the matched layer and the plasma sheath like they do not exist."

According to the researchers, the tricky bit is to keep the matched layer and the plasma sheath smaller than the length of the radio waves. However, Gao believes that it's possible to tune the craft's antenna to compensate

"We don't need to know exactly the properties of the plasma layer, but we need to know the ranges for these properties," says Gao. "The matched layer will be adjusted by an automatic control system, so we only need to know the ranges to make sure this whole system can work appropriately."

This isn't the first attempt to solve the blackout problem, but the team says that this is a lighter and simpler method that doesn't rely on the shape of the spacecraft to work. The researchers also say that the method could be applied not only to returning spacecraft, but also future hypersonic passenger aircraft, missiles, and ICBMs

Source: Journal of Applied Physics

Samsung Makes Big Trucks Transparent in the Name of Road Safety

As reported by The Verge: Back in 2009, Russian design house Art Lebedev introduced the dramatically titled Transparentius concept for improving road safety. It was remarkably simple: put a camera on the front of large, slow-moving trucks and connect it to video displays on the back, thereby informing trailing drivers whether it's safe to overtake the big rig. That's the exact same idea that Samsung is now pursuing with a new prototype truck. Making use of its abundance of outdoor displays, the Korean company has stitched together a video wall of four displays at the rear of the truck, which transmits video captured by a wireless camera at the front.

Samsung says it's now working to obtain regulatory approval for the deployment of its so-called Safety Truck, however the idea doesn't appear economically practical at large scale. The camera might be cheap and simple enough to install, but four displays per truck would be a major investment for any transport company to make, especially since it wouldn't lead to any direct financial benefit. Still, it's impressive that Samsung has managed to overcome the technical challenges (like solar glare) of realizing this otherwise laudable idea.

A more realistic solution to improving information while driving will be provided by Vehicle-to-Vehicle Communication (V2V) systems, which are expected to arrive in US cars next year. This is a form of networked intelligence whereby your car transmits data about its position, direction, and speed, and receives the same about cars around it. It can thus issue alerts about unsafe driving by others or notify of any collisions ahead even before any other drivers have had the time to react. In that way, V2V does even more than just give you vision the way Samsung's Safety Truck would, though making big trucks transparent is undoubtedly a much cooler application of technology.

SpaceX Augments and Upgrades Drone Ship Armada

As reported by NASA SpaceFlight: SpaceX’s aspirations towards recovering launched Falcon 9 first stages are continuing to focus on ocean based landings, ahead of realizing the goal of returning the cores back to land. With continual refinements to the approach, SpaceX have welcomed new and improved Autonomous Spaceport Drone Ships (ASDS), one of which has been sighted taking a cruise down the Panama Canal.

Marmac 300 – The First Drone Ship:

In November 2014, Elon Musk confirmed reports of SpaceX’s “Autonomous Spaceport Drone Ship (ASDS)” – providing an overhead photo of a 300-foot-long ocean-going barge with a deck widened with steel “wing” extensions to a span of 170 feet.

The barge sported a large white “X” logo in the center of two giant concentric circles, marking the spot at which Musk hoped the first stage of a SpaceX Falcon 9 v1.1 rocket would soon touch down during an ocean landing somewhere off the east coast of Florida.

Mr. Musk’s “drone ship” photo was the first visible evidence that SpaceX was serious about attempting to recover a launched first stage.

Earlier that year SpaceX had filed with the U.S. Patent and Trademark Office requesting a review of rival company Blue Origin’s patent for a method of landing a rocket stage at sea.

SpaceX claimed that the Blue Origin patent should not have been granted, since similar methods had been described by other inventors long before Blue Origin filed for their patent.

Evidently SpaceX had confidence it would prevail in the patent dispute, since the “drone ship” was unveiled to the public mere months after filing for the patent review, and long before a decision could be expected from the Patent Office – which later announced in March that SpaceX’s dispute had enough merit to go forward in a review process which is now ongoing but may not be resolved until 2016.

Soon after, photos appeared showing the drone ship en route to her new home port in Jacksonville, Florida.Mr. Musk presented his company’s first drone ship as using thrusters repurposed from deep-sea oil rigs, able to hold its position at sea to within three meters even in a storm, and perhaps able to allow future refueling and fly-back of the rocket stage to its launch site.

Despite its fanciful name, the drone ship was built on a rather mundane barge. The Marmac 300 had been a maritime workhorse for over 15 years, doing drudgery for its owner McDonough Marine Service that included being submerged beneath the keels of sunken vessels and then refloated to effect their recovery.

Now, in addition to wing extensions, Marmac 300 carried four diesel-powered hydraulically-driven thrusters for position-keeping, diesel fuel tanks and several large steel shipping containers at either end of the deck housing communications gear, an autonomous guidance system and additional equipment.

The drone ship was towed to her new home in the port of Jacksonville, to the north of the Cape Canaveral, probably relating to a decision to minimize her travel distance to the landing zone on rocket recovery missions, since Falcon 9 flights typically travel north-east from Cape Canaveral out over the Atlantic.

The winged Marmac 300 got her first chance to catch a Falcon 9 stage in January of this year, during the CRS-5 resupply mission to the International Space Station.

Unfortunately, the incoming stage ran out of the hydraulic fluid needed for operation of the aerodynamic “grid fins” used for precision guidance, and the stage crashed into the drone ship and was destroyed.

However, rather than downplay the mishap, SpaceX released spectacular video footage of the event and vowed to try again with extra hydraulic fluid. Also, the ASDS proved herself up to the challenge, sustaining only minor damage.

Afterwards, Mr. Musk noted she was being repaired and that she would be given the fanciful new name “Just Read the Instructions,” after a fictional spaceship commanded by an artificial intelligence in the Iain M. Banks novel “The Player of Games”.

On this first recovery attempt, SpaceX demonstrated what would become more or less their standard operating procedure. The drone ship left port several days before the schedule launch attempt, towed by a dedicated tugboat named Elsbeth III. Shortly after, the support ship “GO Quest” left port to join the convoy.

Once at – or near – the landing zone, Elsbeth III’s crew would presumably start up the drone ship thrusters and set her free to auto-position herself at pre-programmed GPS coordinates.

Elsbeth III and GO Quest – which appears to carry a large satellite dish on deck – would then stand off at a safe distance during the landing attempt.

The drone ship was fitted with deluge water jets that flooded the deck with ballast water from the barge’s tanks, for cooling the deck from the blast of the landing rocket engines.

Some time before the incoming stage was expected, the water pumps would be started and the deck flooded. Some of the on-deck photos later provided by SpaceX showed water jets flooding the deck as the incoming stage came into view.

During the landing attempt, the drone ship was transmitting video back to SpaceX launch control facilities for real-time visual monitoring of the landing.

It appeared during SpaceX’s webcast of this and later recovery attempts that SpaceX mission control personnel were seen to be watching a near-real-time video feed from the drone ship, based on their reactions as they watched their monitors, and based on Musk’s tweets shortly after the fact with details that suggested he had seen the event.

No crew were on board the drone ship during the attempt, hence the “autonomous” label.

Hans Koenigsmann, SpaceX’s Vice President for Mission Assurance, said in a press conference before the CRS-5 mission that it would take about one to two hours after a landing for the crew to safe the stage remotely before boarding the drone ship.

Remote-controlled safing activities would likely include venting pressurized helium from the fuel tank and venting residual LOX.

Once the crew had boarded the drone ship, the stage would be secured for transport.

Although Musk has said the stage would be stable because of the weight of its engines and their support structure at the aft end of the stage, he has mentioned that steel “shoes” might be welded to the deck over the feet of the stage’s legs for added insurance.

There have also beenmentions of chains attached between the deck and the aft of the stage.

Once back in port, the stage would be offloaded by crane, further safed – fuel drained, etc – placed on a “breakover” fixture to rotate it horizontal, then loaded onto a truck and transported by road to either SpaceX’s facilities in McGregor, Texas or SpaceX’s Spaceport America base in New Mexico for additional inspections and testing.

Following CRS-5, the drone ship’s next recovery mission came in February with the launch of the DSCOVR spacecraft for NASA.

Unfortunately, heavy weather at sea knocked out one of the four thrusters and SpaceX reported that 3-story waves were breaking over the deck.

The company called off the landing attempt on the drone ship, and “Just Read the Instructions” returned to port with visible damage to on-deck equipment apparently caused by wave impact.

Soon after, Mr. Musk reported that he planned significant upgrades to the drone ship so that it could handle “literally anything” in the future. As a result, the drone ship was subsequently fitted with a vertical steel bow wall and two more powerful bow thrusters.

Marmac 300 got her last shot at glory during the CRS-6 ISS resupply mission in April, but was once again thwarted by a wobbly landing of the Falcon 9 first stage, which touched down on deck but couldn’t keep itself upright and toppled over – rupturing its propellant tanks in dramatic fashion.

However, SpaceX had made progress, as the stage did not run out of hydraulic fluid this time and appeared oh-so-close to sticking its landing.

SpaceX also introduced a new innovation in making a video of the event, using a camera-equipped flying drone to launch itself from the ASDS, hover at a distance, take video of the landing attempt, and return to the ASDS.

Despite the temporary conflagration caused by the stage impact, the flying drone was able to return and land on the ASDS, allowing SpaceX to later recover the data card from the camera and publish the dramatic video.

Shortly after the abortive CRS-6 attempt the drone ship was towed back to the shipyard where she had been outfitted in Morgan City, Louisiana. In June, a new drone ship built on McDonough’s Marmac 304 barge appeared in Jacksonville as her replacement.

While SpaceX has not said why Marmac 300 was retired, she may have served as a prototype not intended for long-term service. Marmac 304 is a much newer barge that has not seen heavy prior use, and may be considered to have a longer life ahead of her.

Marmac 304 – The Next Generation:

The new drone ship built from Marmac 304 reported for duty at Jacksonville in early June, albeit in unfinished condition.

With dimensions virtually identical to Marmac 300, she carries some new features, including a steel blast wall erected between the rear containers and the landing deck, in addition to the steel bow wall as previously seen on Marmac 300.

Ongoing work visible on deck suggests that a second blast wall may be installed at the forward end of the landing deck as well.

These – and other preparations – are expected to render Marmac 304 operable in time for the upcoming CRS-7 mission to resupply the Space Station in late June.

Marmac 303 – Of Course I Still Love You:

Shortly after Marmac 304 headed east from Louisiana, her sister barge Marmac 303 left the same port and went south for the Panama Canal.

Carrying the wing extensions reportedly clipped from Marmac 300, Marmac 303 reached the Panama Canal on June 9 and began her transit June 14, exiting the Canal on the 15th.

Since the wing extensions – if attached – would make the barge too wide to transit the canal when attached, they were laid on her deck in sections as cargo and will be attached permanently when she reaches California in about three weeks.

Towing Marmac 303 is the tugboat Rhea, sister ship to the tug Elsbeth III which tends to Marmac 304. After being fitted with her wings and readied for service, she will go to work catching Falcon 9 first stages from SpaceX’s launch pad at Vandenberg Air Force Base.

Although no announcement has been made of her expected operational date, the upcoming Jason-3 mission from Vandenberg would be her first opportunity to attempt a stage recovery.

SpaceX has said they hoped to be permitted to attempt a return-to-launch-site landing of the first stage at Vandenberg, but to date it appears that permission may not yet have been granted, and the landing pad that would be used for such an attempt at SLC-4W was shown in a recent photo to consist only of graded earth with the concrete pad not yet poured.

According to Musk, the west coast drone ship will be dubbed “Of Course I Still Love You,” after another fictional spaceship from the mind of science fiction writer Iain M. Banks.

Future Plans:

The drone ship is apparently a mandatory stepping stone in SpaceX’s ultimate goal of having Falcon 9 first stages return themselves after launch with a “boostback” maneuver to the launch site, for a soft landing on terra firma.

SpaceX is now building landing facilities at both Cape Canaveral (LC-13) and Vandenberg Air Force Base (SLC-4W). According to Mr. Musk, officials have asked for “repeated, successful” demonstrations of a first stage landing on the drone ship before a landing attempt will be allowed at the Cape.

SpaceX is also building a new company-owned launch facility near Brownsville, Texas, for commercial satellite launches over the Gulf of Mexico. The Texas launch facility would be SpaceX’s third orbital launch facility and yet another potential base for drone ship operations.

Even after Falcon 9 first stages begin landing at launch sites, there may be continued opportunities for downrange landings on drone ships. Some higher-energy missions and heavier payloads would prevent the first stage from reserving enough propellant to boost itself back to the launch site, making downrange landing on a drone ship the only option for recovery.

Also, the drone ships may also be called on to recover stages from SpaceX’s next launch vehicle, the Falcon Heavy, which will have a central core flanked by two side boosters.

Both side boosters and the first stage of the vehicle’s core will be designed for autonomous landing, and Mr. Musk has said there may be missions in which the boosters fly back to the launch site but the first stage of the core lands downrange on a drone ship.

In his first “drone ship” tweet, Mr. Musk held out the tantalizing possibility that the drone ships would eventually allow recovered stages to be refueled, launched from the deck, and fly themselves home. Time will tell if SpaceX can make this dream a reality.

In the meantime, it seems increasingly likely that the company could pull off a successful landing of a Falcon 9 first stage on a drone ship soon, perhaps as early as this month.

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.