Precision GPS: On the Road to Driverless

Land-vehicle autonomous navigation requires centimeter-level qualification tools to enable confidence build-up for delivery to open-road traffic insertion. External positioning sensors over a dedicated road section can be replaced with an embedded high-accuracy, highly responsive epoch-by-epoch differential GNSS receiver coupled with an inertial navigation system. The demonstrated absolute accuracy and mobility extends the potential test area and minimizes cost for multi-environment validation. 

As reported by GPSWorld:  Personal cars and commercial trucks are continuously improving the driver experience and safety thanks to integration of more significant and machine-assisted control systems. Advanced driver-assistance systems (ADAS) are now integrated in all luxury cars and moving into mainstream products. Technologies covered by ADAS are specific for each car integrator, but increasingly they include now involving more safety features, such as driver assistance and partial delegation to autonomous control for small maneuvers such as lane control. The generation of ADAS systems introduced in early 2015 on high-end models are engaging more intelligence from the control system such as:

• Lane departure warning system
• Speed assistance and control
• Driver assistance and control
• Autonomous emergency braking.

It is not only individual drivers who want this technology, but also governments that are getting involved to prevent accidents and minimize the economic impact associated with them. In the European Union, the general safety regulation 2009/661 was the first step to engage member-states to act as a regulator to mandate car safety improvements. The European Transport Safety Council, a non-profit private association, released in March 2015 a position paper titled “Revision of the General Safety Regulation 2009/661.” It promotes the introduction of lifesaving technologies like intelligent speed assistance, autonomous emergency technology including all speed and pedestrian detection, and lane-departure warning systems as the next step of regulation.

Car manufacturers are not far behind. They understand their customers’ expectation of minimized risk and enhanced driving experience. Telematics is also a path to convert a single vehicle into a fully intelligent, connected and entertainment object with an associated high value. So every car manufacturer is willing to be seen as a technology master.

Toyota, for example, plans to integrate collision-prevention technology in all its mainstream and luxury cars by 2017. The ADAS new generation focuses on radar-activated cruise control technology for the collision-prevention system. The control system maintains distance from a vehicle ahead and can stop the car if driver doesn’t react. The next step is to monitor driver attention with sensors like cameras focusing on the driver’s eyes, and the pressure of the hand on the steering wheel.

However, no fully driverless car is expected in the next 10 years. This technology is limited by legal issues and the lack of reliable nationwide mapping data.

Since the technology must be fully proven to prevent any lethal threat on the user and other drivers, most car and truck companies are working actively on qualifying driverless technology today. Nissan began testing driver-assist technology on open-road traffic in Japan in late 2013. It enables highly advanced systems such as lane-keeping, automatic lane change, automatic exit, automatic overtaking of slower or stopped vehicles, automatic deceleration during congestion on freeways, and automatic stopping at red lights. This is a step towards attaining fully automatic driving, targeted for 2020 by Nissan.

Some European manufacturers such as Daimler Benz are also early adopters. Daimler/Mercedes uses the Bertha Benz prototype car to test autonomous driving technologies. It merged multiple vision, radar and GPS sensor with digital map to monitor an open-road 100-kilometer trip in August 2013 (Figure 1).

Figure 1. Bertha Benz test car, left, running fully autonomous 103-kilometer trip in open road including 27 percent narrow urban roads. Right, networked sensor systems of the S 500 Intelligent Drive research vehicle.

All manufacturers are building driverless capability into their technology demonstration concept cars:

• Mercedes with F 015 Luxury presented at the Consumer Electronic Show, early 2015;
• Audi with Prologue, an extrapolation of test car RS7 concept equipped with SuperFast driverless pilot;
• BMW’s electric i3 car is integrating ActiveAssist technology that enables portions of drive to be without any manual intervention, such as car parking and autonomous rally to a meeting point;
• Google’s self-driving vehicle that conforms to California license requirements for driverless tests in open traffic;
• Tesla model SD autonomous test car.

Although most market leaders agree that this is not a technology for mainstream production in the next few years, they all work very efficiently to master the technologies. It is a big challenge to integrate all the sensors and the navigation functions to autonomously and accurately position the vehicle on a map. The whole system must be certified to prevent any liability in case of a crash, a case that would engage the solution provider and the vehicle manufacturer.

A large part of the qualification task will benefit from simulations and integration testing platforms in realistic conditions. At the very least, a very robust final open-space validation test must take place. Car manufacturers/integrators are using private test facilities in open air to perform serious trials before proceeding to real traffic conditions. Renault uses a 10-square-kilometer facility in France (Figure 2) to perform private tests in a protected area.

Figure 2. Renault outdoor test center at Aubevoye, France.

New autonomous car drive tests have mandated equipment enabling measurement of the car’s position on the track with an extremely high precision and repeatability. There are two competing technologies to do this:

• Install many location sensors on the test track;
• Use a general absolute positioning system.

Here we focus on an absolute positioning system that is affordable, easy to install and low maintenance. It is based on two main assertions:

• The autonomous pilot can position accurately on the test track;
• The test track is accurately referenced to the absolute positioning system.

We focus more closely in this article on the first assertion; the second one can be covered with a specific calibration trial where equipment, as discussed further, can be used in quasi-static mode and experience consistent accuracy. Let us have a deeper look at the candidate position technologies to verify autonomous pilot accuracy.

Positioning Technologies

Many technologies have been proposed to obtain vehicle position on the course. However, they all must be compatible with a reliable mapping database. Given the lack of consistent road infrastructure equipment with alternative capabilities, GNSS positioning is the sole enabling method to fit to a map every place around the world. That is why driverless systems always include a GNSS sensor to help other data matching with the map. The versatility and low cost of GNSS positioning makes it a candidate for open-air validation as well.

Standalone Standard Positioning Service GPS. The SPS single-frequency GPS receivers are included in so many nomadic appliances today that they are a commodity. Since their introduction 20 years ago, their performance is well understood. Some trials were performed in different area profiles with satellite constellation position dilution of precision (PDOP) < 2. Worse results were obtained from deep urban canyons in downtown Seattle, Wash.

For every technology, the relevant performance for the test course is the lateral error to the expected center of the lane in the two horizontal dimensions, referred to as 2D or N/E for orientation north and east.

For standalone SPS GPS, the lateral error standard deviation in 2D can be as high as 46 meters and have peak errors up to 660 meters. Lateral error in 3D can be as high as 20 meters with peak errors up to 175 meters.

Such performances are out of range for any positioning verification. It can only deliver a rough estimate of the point on the map, but would not provide tight correlation with other sensors for the navigation system.

Hybridized IMU and SPS GPS. Coupling of an absolute navigation GPS receiver with an inertial measurement unit (IMU) can mitigate corruption of the navigation solution when intermittent GPS signal outage is encountered. The hybrid approach is beneficial on any difficult signal transmission path from the satellite that is not line-of-sight: in urban canyons, deep foliage, under bridges, tunnels and in any multipath area. It also yields benefits in the very short term (less than a few seconds) for dispersion on the position computed from the sky.

Over the last 10 years, the combined benefits of micro-electro-mechanical sensors (MEMS) and tight coupling algorithms have raised the bar of positioning accuracy. It enables smoothed position along track and dead reckoning (DR) in case of GNSS signal outage.

Lateral error standard deviation in 2D is lowered to 2.3 meters and peak error up to 10 meters. However, this performance is still too poor to validate a vehicle position in the lane.

Hybrid Differential Single Frequency and IMU. The next step to mitigate systematic errors of the GNSS system is to use a set of multiple reference receivers in the vicinity of the area covering the test course. The reference receivers are static. The position of the reference is determined using long-term averages to mitigate constellation errors. A minimum for a position fix of 20 minutes is commonly reported. Then the position error standard deviation in 2D is less than 2 centimeters for baselines shorter than 100 kilometers.

For a MEMS integrated with a standard SPS GPS single-frequency receiver with DGPS correction on a mobile platform moving at less than 70 km/hour with HDOP < 1.4, Table 1 compares performance in a 2013 test.

Table 1.IMU performance grades.

Table 2. Horizontal error performance.

Hybrid Differential Dual-Frequency Carrier Phase and IMU. The GNSS solution can be further improved, taking into account both L1 and L2 frequencies to mitigate propagation error and carrier phase to achieve ultimate signal accuracy. The combination of both helps solve ambiguities associated with the carrier-phase technique. When combined with a MEMS IMU, accuracy confirmed with HDOP < 1.6 is:

• Lateral error standard deviation down to 0.18 meters;
• Peak error of 0.6 meter.

However, this is still insufficient accuracy when compared to 0.1 meter required for verification testing.

With such low-cost IMU, GPS outages produce a rapidly increasing lateral error over elapsed time. The lower the speed, the poorer the position result.

Another limitation common to many differential solutions is the turn-on delay for the solution. It is also a repetitive issue in case of disruption of the GNSS solution. It extends the delay to recover from DR situation.

Geodetics’ Epoch-by-Epoch

Geodetics Inc. has developed a new class of instantaneous, real-time precise GPS positioning and navigation algorithms, referred to as Epoch-by-Epoch (EBE) and employing hybridized dual-frequency differential GPS with a high-performance IMU.

Compared to conventional real-time kinematic (RTK), integer-cycle phase ambiguities are independently estimated for each and every observation epoch. Therefore, complications due to cycle slips, receiver loss-of-lock, power and communications outages, and constellation changes are minimized. There is no need for the initialization period (several seconds to several minutes) required by conventional RTK methods.

More importantly, there is no need for re-initialization immediately following loss-of-lock problems such as those that occur when a mobile GPS receiver passes under a bridge or other obstruction, or when it loses satellite visibility during a shaded portion of road. In addition, EBE provides precise positioning estimates over longer reference-receiver-to-user-receiver baselines than conventional RTK.

This feature supports testing for long-range operations, for example, such as positioning a vehicle on a lane. The reference receiver is set in the vicinity of the test center track.

EBE requires the use of a minimum of two receivers, each of which is tracking a common set of five or more satellites and providing simultaneous dual-frequency phase data. Typically, one of the receivers is stationary, but this is not a requirement.

EBE has been proven utilizing dual-frequency receivers and operating at distances of up to 50 kilometers from the nearest base station in unaided mode. Additionally, the EBE algorithms operate in a network environment and make optimal use of all GPS measurement data at each epoch, gracefully degrading the position accuracies when some measurement data are not available. Furthermore, the system will make use of an IMU system, compensating for outages when line-of-sight to the satellites is blocked. This produces a robust and more reliable system.

Epoch-by-Epoch can deliver several benefits including:

• Computationally efficient algorithms that provide a position estimate based on a single epoch in several milliseconds. This allows the real-time position estimate to be computed on the user platform (assuming reference station data is sent to the user platform).
• An initialization period is not required. Since RTK requires some period of time (that can be measured in seconds to minutes) to perform ambiguity resolution, this is an important capability for platforms that:
  • require high accuracy (for example, for end-game scoring);
  • cannot see the satellites until launch;
  • have short flight or test course duration;
• A re-initialization period following loss-of-lock is not required, unlike RTK, which needs to restart the integer-cycle phase ambiguity resolution process. This is another important capability because vehicle monitoring is considering EBE for dynamic applications where loss-of-lock and loss-of-data are likely.

However, it must be mentioned that many of the GPS receivers in use by the test (and training) community today do not support this dual-frequency requirement. Hence, those systems could not realize the maximum benefit.

This technology is implemented in a rugged modular platform (Figure 3) with three main units:

• A dual-frequency GPS antenna,
• An integrated INS coupling GPS receiver with either an internal MEMS IMU or external IMU,
• An external fiber-optic gyroscope (FOG) IMU for high-end accuracy and reliability. The external IMU is optional and dedicated to increasing the DR capability.

Figure 3. Dual-frequency differential navigation unit hybridized with external fiber-optic gyro.

Performance. Tests have been performed in conditions close to the land-vehicle navigation validation. It is based on measurements on-the-fly with no post-processing except for evaluation of the error.

The first case is a static position of the rover 4.8 kilometers away from the reference receiver. Positions are updated once per second. The system includes a FOG IMU. the lateral error peak is less than 4 centimeters. Bias error is less than 1 centimeter. See Figure 4.

Figure 4. Single point error when rover is static.

The second test case is with a high-dynamic mobile platform, moving at a speed of 200 km/h, with an average distance from the reference to the rover of 6 kilometers. Lateral error standard deviation is 0.5 centimeters, peak error is less than 2.2 centimeters. Bias error is lower than 0.2 centimeters (Figure 5).

Figure 5. Dynamic trial test single point error.

The performance in these test cases meets the expected accuracy for validation of autonomous navigation.

One last method to increase accuracy is to switch to a different class of IMU performance, from tactical grade to advanced. When in the line-of-sight of the GNSS sky-view, the performance is the nearly the same.

Conclusion

A real-time, differential Epoch-by-Epoch, dual-frequency carrier-phase GPS receiver, tightly hybridized with a high-performance IMU can provide absolute error lower than 5 centimeters in the 10-kilometer baseline range of the reference static receiver. This is fully adapted to the qualification of driverless auto-pilot systems for the targeted year of 2020. It can avoid the need to use complex theodolite and vision calibration systems. It provides maximum flexibility  and minimum sustaining costs.

A Dialog of Car and Highway

As reported by BITS: One peek at all the electronics under the hood is proof that today’s car is as much computer as engine. Examine the larger picture, and you’ll see how much the stuff around cars is becoming smarter, too.

Smart roads, toll plazas, traffic lights and signs are all increasingly connected to cars. Connected cars are talking to one another, and to the devices over and around them. Often the reasons for this will involve cost savings and faster-moving traffic. Travel will be safer, too, advocates say.

“Cars won’t be by themselves anymore, they’ll be connected to the road and each other,” said Eric-Mark Huitema, a manager in IBM’s “Smarter Cities” initiative. “Eventually there won’t be many accidents, which means you can reduce the weight of a car by 70 percent, all the metal we put in there to protect people. Cars might be made of glass.”

That is a decade or more away, but already IBM says it has helped reduce traffic by 25 percent in Stockholm, in part by examining traffic patterns and telling people the best times to drive. In Singapore, there is a pilot project to override traffic lights when the roads detect an accident. At IBM buildings in Copenhagen and Amsterdam, the company monitors bicycle use among employees in some locations, giving bonuses to people who forgo autos for bikes on a daily basis.

There does seem to be both money and enthusiasm for more of the same, in the interest of polluting less while managing larger populations. Navigant Research, which looks at clean technology markets, estimates that spending on smart cities will reach $27.5 billion by 2023.

In some ways, the future is already here. According to the management consulting firm Oliver Wyman, by next year some 210 million cars on the world’s roads will be connected wirelessly in some form to the Internet and to services like OnStar, General Motors’ connected-vehicle subsidiary.

The Federal Communications Commission has since 2003 reserved a segment of radio spectrum for communications among cars, and between cars and the surrounding infrastructure. While the spectrum cannot send information far, it can send exceedingly fast signals, so that high-speed traffic can be followed and adjusted.

“This will be amazing,” said Byungkyu Brian Park, a professor at the University of Virginia’s Center for Transportation Studies. “Right now the sensors aren’t two-way, and get used for things like toll tags, but soon you’ll be approaching an intersection and the car will know how long a light will be green. If the driver is elderly, it could lengthen how long the light is yellow.”

But the trade-off could well be the independence long associated with driving a nice car.

The number of connected vehicles goes much higher if you count the smartphones people have in their cars. Behavior can be monitored through driving apps like Automatic from Automatic Labs, which evaluates a person’s safety habits, like braking and acceleration. Sometimes those apps already share information, in making real-time maps of congestion during rush hour. It is an easy thing to increase the amount of data.

“We live in a world where your car is talking about you,” said Rob Ferguson, director of engineering at Automatic Labs. There is also technology inside cars, like adaptive cruise control and lane-keeping assistance, that if it isn’t online already could be made into two-way feedback systems with sensors in pavement and signs to manage traffic.

The goal is steady flow, which works out better and faster for all concerned. Digital signs of congestion ahead could compel drivers to slow down, trading autonomy for a faster commute for all.

The movement from individual vehicles to networked systems is already happening with trucks, ships and trains, and may be further ahead. That is partly because the owners are usually not the ones operating them and have more interest in efficiency than operator autonomy.

In Europe, many trains are already equipped with information about which cars have the most available seats. In Shanghai and Rotterdam, incoming ships notify the networks running the docks, and are advised which docks have the most available space. That is coordinated with fleet trucks, which pull up to load cargo.

Research by the University of California, Berkeley, on trucks traveling together found fuel savings of 5 to 20 percent in convoys because the vehicles move at a uniform rate, saving the fuel needed in acceleration, and because of reduced air resistance. In addition, about 40 percent of accidents happen at intersections, and smarter traffic lights could help manage that flow better. Those insights will probably affect what happens to cars.

“Seatbelts, airbags, anti-lock brakes and stabilization systems were all mandated for safety,” said Steven E. Shladover, a researcher at Berkeley’s advanced transportation technology program, who has been studying technology and transport for four decades. “Roadsides will tell you the most efficient speed to use. Traffic lights will choose whether to keep a yellow light on and let a truck through.”

Because trucks weigh much more than cars, they can tear up pavement with hard braking and slow traffic with their gradual acceleration. Traffic lights may be programmed to let large vehicles through. Pavement for convoy trucks could be hardened, leading to less wear on highways.

Rush hour may be faster, but it also may be a lot more dense. In his research, Mr. Park at the University of Virginia has determined there is a minimum delay of about 1.8 seconds between cars, which means 2,000 cars an hour can flow through a single lane of highway, if there’s no congestion. If cars become cooperative and managed, he thinks, that can be decreased to 0.6 second, or 6,000 cars an hour.

“You’ll have cooperative cruise control, more efficient parking, priority at traffic lights to people sharing rides,” Mr. Park said. “It will be a huge change.”

FCC Net Neutrality Rule Goes Into Effect Today

As reported by CNET: The Federal Communications Commission's open Internet rules will take effect today as planned after a federal court rejected requests by opponents to delay the rules pending lawsuits against the agency.

A three-judge panel of the US Court of Appeals for the DC Circuit on Thursday denied a request filed by wireless and broadband industry groups to delay the FCC's adoption of so-called Net neutrality rules. The court's denial of the request means that the new rules, which reclassify broadband as a public utility and prohibit broadband providers from slowing down or blocking Internet traffic, will go into effect as planned on Friday, June 12.

The ruling by the court comes as a relief to the FCC, which is facing several lawsuits over the rules, which were approved by a 3-2 vote in February.

The Net neutrality regulations are based on a new definition of broadband that lets the government regulate Internet infrastructure as a public utility. The rules prohibit broadband providers from blocking or slowing down traffic on wired and wireless networks. They also ban Internet service providers from offering paid priority services that could allow them to charge content companies, such as Netflix, fees to access Internet "fast lanes" to reach customers more quickly when networks are congested.

FCC Chairman Tom Wheeler called the ruling on Thursday a huge victory for Internet consumers and innovators.

"Starting Friday, there will be a referee on the field to keep the Internet fast, fair and open," he said. "Blocking, throttling, pay-for-priority fast lanes and other efforts to come between consumers and the Internet are now things of the past. The rules also give broadband providers the certainty and economic incentive to build fast and competitive broadband networks."

The FCC's rules were adopted in February and were published by the government in April. Following a standard 60-day waiting period, the rules go into effect on Friday.

Broadband providers have said they are willing to accept the basic principles outlined in the Net neutrality rules that prevent broadband providers from blocking or degrading traffic on their networks and prevents operators from offering "fast lanes" that deliver some content, like Netflix videos, faster than other content. But they are vehemently opposed to the FCC's reclassification of broadband as a public utility like the old-style telephone network.

Opponents claim this approach will lead to government rate regulation and will stifle investment in networks. Meanwhile, Net neutrality supporters argue that the rules are necessary to prevent operators from acting as gatekeepers to the Internet. They claim that reclassifying broadband was the only way to make sure the rules withstood legal scrutiny.

AT&T, the National Cable and Telecommunications Association, the U.S. Telecom Association and the CTIA mobile trade group are among a handful of groups that filed suit against the FCC in April accusing the agency of overstepping its authority when it decided to treat broadband like a public utility.

These groups also asked the court to put the rules on temporary hold while the lawsuit against the FCC was ongoing. In a brief statement, the DC Circuit judges stated that the Internet providers "have not satisfied the stringent requirements" to block the rules while their underlying lawsuit is pending.

CTIA President Meredith Attwell Baker acknowledged that the court's ruling was a disappointment, but not unexpected. She vowed to continue the fight.

"While the stay decision is disappointing and a loss for consumers, securing a judicial stay is always a challenge given the extremely high standards," she said in a statement. "The case is just beginning and the stakes are high."

Efforts in Congress to craft legislation that would make basic Net neutrality rules law, but would not treat broadband as a utility, have largely stalled. A win for the Internet providers could have forced a compromise from Democrats. Meanwhile, congressional Republicans are attempting to prevent the FCC from enforcing its Net neutrality rules by including amendments in a must-pass budget bill. The provision would have to be passed by both the Senate and House of Representatives and still get President Barack Obama's signature. The president has been a strong supporter of Net neutrality and ahead of the FCC's vote, urged the agency to reclassify broadband.

Tesla CEO Musk: Some Model S Owners to Get Hands-Free Steering

As reported by the LA Times: A small number of Tesla Model S owners will have their cars updated for a test of hands-free driving by the end of the month, Elon Musk, chief executive of the electric car company, said at Tesla’s annual shareholders meeting Tuesday.

Speaking at a standing-room-only meeting at the Computer History Museum in Mountain View, Calif., Musk outlined how he expects auto-pilot cars will become road ready.

He said the Palo Alto automaker’s efforts to develop a battery-swapping network for its electric cars have faltered and announced that the Model X, Tesla’s long-delayed sport utility vehicle, will reach the market in three to four months.

At the behest of shareholders addressing the company at the meeting, Musk agreed to look into using vegan materials for seating and other surfaces in Tesla cars. He also announced that Deepak Ahuja, the automaker’s veteran chief financial officer, is retiring but will stay on until a replacement is appointed.

Musk spent much of the meeting talking about the potential for robotic cars.

In the first phase of autopilot development, Musk said, drivers will need to remain fully alert and ready to take over the driving.

The feature is designed to alleviate part of the burden of driving from the driver but not replace the person at the controls. He said such a feature will be legal because the driver would remain responsible for control of the car and in the driver's seat.

“This is not an abdication of responsibility for steering,” Musk said.

But Tesla is aiming for a fully autonomous system in about three years.

“There will be a fully operational autopilot with everything that is needed for someone to go to sleep and wake up at their destination,” Musk said. “But this is an extremely difficult engineering project.”

Tesla would want a fully robotic car to be at least 10 times safer than a human driver before rolling it out, he said. Regulators would likely be even harder to convince, he said.

Speaking of the Model X, Musk said it will be the safest sport utility on the road. The electric architecture locates the heavy battery pack on the floor pan of the car, lowering its center of gravity and making the vehicle almost impossible to roll over, he said.

Musk said Tesla engineers are working out the final details of the car before approving it for production.

“Getting those final nuances right for the Model X is what we are focusing on right now,” Musk said.

The auto executive told shareholders that Tesla should do more to emphasize the safety of its cars, which he claimed had lower injury rates than other vehicles.

“As we can show statistics on accidents and so forth, it should translate to lower insurance rates,” Musk said. “We will have to work with insurance companies to make sure they are factoring in the actual accident rates for the Model S and Model X.”

Musk also disclosed that a much publicized effort to allow people to pull into roadside stations and swap a spent battery for a fully charged one has not worked out.

Tesla built such a station on Interstate 5 at the Harris Ranch, a midpoint on the drive from Los Angeles to San Francisco, but Tesla owners aren’t using it.

The automaker issued sample invitations to a group of about 200 California Model S owners to test out the swap system but only a handful used it, and then only once. A wider roll out also failed.

“We are seeing a very low take rate,” Musk said. “People don’t care about pack swap.”

Instead, they use Tesla’s network of free “superchargers” to recharge the cars. It takes longer, but they time it for a coffee break or a meal, he said.

Tesla doesn’t plan to expand its battery swap system, Musk said.

The swap system was important to Tesla because based on California Air Resources Board rules, it provided an opportunity to generate more valuable zero-emission vehicle credits. Tesla has made more than $500 million selling California and federal environmental credits to other automakers.

Airbus' Adeline Project Aims to Build Reusable Rockets and Space Tugs

As reported by Space.com: Europe wants reusable rockets, too.

European aerospace company Airbus has revealed its plans to develop rocket engines that fly back to a runway and a reusable upper stage that acts as a space tug — reusability concepts that mirror those being developed by American spaceflight companies SpaceX and United Launch Alliance (ULA).

Airbus has been working on its Advanced Expendable Launcher INnovative engine Economy (Adeline for short) reusable-rocket concept since 2010 and wants it to be up and running by 2025. The technology could help enable huge satellite constellations that would require a dramatic increase in the number of launches per year, company representatives have said. 

Meet Adeline

As envisioned, Adeline detaches from its rocket's first-stage fuel tank and re-enters Earth's atmosphere at five times the speed of sound with its engines behind the wings and a heatshield. Once in the atmosphere, Adeline uses its wings to autonomously fly toward a runway and, once at subsonic speeds, uses deployable propellers to power its return to the landing site, where it touches down on skids.

Adeline is being proposed for the planned two-stage Ariane 6 rocket theEuropean Space Agency is paying Airbus to develop. Ariane 6 could be flying in the 2020s. Adeline's engines use liquid fuel, such as kerosene and liquid oxygen, which other rockets also use. According to Airbus, this means Adeline could be used with other rockets.

Airbus is not the only company to propose a reusable propulsion module. In April, ULA announced its Vulcan rocket and the Sensible, Modular, Autonomous Return Technology (SMART) initiative, which will allow Vulcan's main engines to be recovered through air capture.

Airbus has become interested in reusability because it thinks the technology could help increase annual launch rates, which in turn would enable the lofting of enormous satellite networks.

"We have to be ready to increase our cadence capability to increase the tons lifted to space per year, while reducing our costs," Hervé Gilibert, Airbus space systems' chief technical officer, told Space.com. "Payloads in future will be smaller and cheaper. We think we are at the edge of a big evolution of our business. You see in our landscape huge constellations that will need a drastic increase in launches per year."

Airbus isn't the only company thinking this way. For example, SpaceX founder and CEO Elon Musk has spoken of launching a constellation of 4,000 broadband Internet satellites into low-Earth orbit (LEO). A company called OneWeb has plans for a 650-satellite network. Other LEO business proposals since the early 1990s have proposed large numbers of telecommunication and imaging satellites.

Adeline vs. the Falcon 9

Since the dawn of the space age, engineers have wanted to return expensive launch vehicles to Earth for reuse, rather than let them burn up and be destroyed in the atmosphere. See our history of reusable rocket technology in this full infographic.
Credit: By Karl Tate, Infographics Artist

View full size image

Up to 80 percent of a rocket's cost is in its propulsion module, which can also contain the flight-control electronics, according to Airbus representatives. Airbus is predicting 30 percent savings for its reusable system compared to existing rockets, as a result of reduced production costs, Gilibert said.

Airbus claims its concept is more cost-effective than SpaceX's ongoing effort to develop a Falcon 9 rocket with a reusable first stage.

Gilibert also claimed that, with Adeline, Airbus' partially reusable Ariane 6 would have a payload performance that is better than SpaceX's reusable Falcon 9. The first stage of the Falcon 9 releases its upper stage and then descends, engines first, to land vertically using legs that deploy outward from the sides of the stage. (The rocket's upper stage is expendable.)

The Falcon 9 first stage needs 44 tons of propellant to reach a vertical landing site, according to Gilibert, and Adeline does not weigh as much.

"My guess, with a given launcher, is that [Adeline's] impact on payload performance, which for SpaceX is huge because it is a loss of 30 to 50 percent of the mass of the payload for a given orbit — our loss will be much lower," Gilibert said.

However, whereas SpaceXhas been flight-testing its vertical landing system when launching customer payloads — and has twice nearly landed the Falcon 9 first stage on a floating platform in the Atlantic Ocean — Airbus has not yet developed the reusable rocket engine Adeline calls for. The company has made more progress with the deployable propellers, though. [SpaceX Rocket Crashes During Landing Attempt (Video)]

Gilibert said that Airbus patented the deployable propellers up to two years ago, and prototypes were wind-tunnel-tested six to eight months ago.

"The proof of concept has been done. This [deployable propeller] concept is now de-risked," he said.  Airbus engineers have also flown a scale-model version of Adeline for landing tests.

Accommodating Adeline

The European Space Agency-funded rockets Ariane 5 and Vega are flown by launch provider Arianespace from a spaceport in French Guiana, in South America. Gilibert said that if Adeline is used with the Ariane 6, that rocket's launch pad will need "very limited adaptations" to make room for the wings.

He also claimed that, because Adeline's engines are protected by the heat shield on re-entry, their condition would be little different than those that have had a ground firing test, which all rocket engines experience prior to launch. As engines must be treated after the test fire to be ready for launch, Gilibert said engineers know what needs to be done, and he is not expecting a "lot of refurbishment" will be required to return Adeline to flight readiness.

The limited work could be carried out at the French Guiana spaceport, he added.

Whereas Adeline uses liquid fuel, Airbus' reusable upper stage/space tug concept employs electric propulsion and never returns to Earth. Electric propulsion involves accelerating electrically charged gas ions, typically xenon, using magnetic fields. The system requires relatively long periods of time to accelerate a spacecraft to high speeds, compared to traditional chemical propulsion.

Gilibert said the space tug would be left in orbit by the Ariane 6 and would be used "several times" to take payloads in LEO to a higher orbit. Each time the tug is used, an Ariane 6 second stage would rendezvous to deliver the payload and provide gaseous fuel resupply. Gilibert also suggested that other rockets, not just Ariane 6, could use the tug. Once the tug's operational life comes to an end, it can be sent on a remote exploration mission, Airbus representatives said.

International Space Station Shifts Orbit Position After Soyuz Glitch, Russians Say

As reported by Fox News: A glitch at the International Space Station on Tuesday caused its position in orbit to change, but the crew was not in danger, the Russian space agency said.

Roscosmos said the engines of a Soyuz spacecraft docked at the station unexpectedly started during testing of the radio system that controls the docking procedure.

Steps were taken to stabilize the station and specialists were now working to determine what caused the engines to start, the agency said.

Two Soyuz spacecraft are docked at the station, and one of them is scheduled to return three of the six crew members to Earth this week. Roscosmos did not specify which capsule had the malfunction, but said the landing would go ahead as planned.

Tuesday's problem follows the failure of a Soyuz booster rocket, which in addition to launching the manned Soyuz spacecraft also is used to send Progress cargo ships to the space station.

A Soyuz rocket carrying a Progress suffered a breakdown after a launch in April, prompting Russia to delay the landing of the three crew members and the launch of a new three-person crew. The landing, originally planned for last month, was rescheduled to Thursday.

Facebook and Google are Out of the Space Race

As reported by Quartz: Who wasn’t excited to see Facebook and Google battle for dominance of low-earth orbit?  Alas, it wasn’t meant to be: both companies are shelving their ambitious plans for satellite internet.

The tech-news site 'The Information' reports that Facebook is dropping its plans for a geo-stationary satellite over concerns that it will not recoup costs. Google, which hired satellite entrepreneur Greg Wyler to prepare an satellite constellation in 2014, backed out of that plan earlier this year.

Titan Aerospace is a Google supported project that uses solar powered
drones to provide network communications systems.

To which satellite experts might say: We told you so. Ambitious satellite-internet projects have a history of failure. Satellite-internet services today are fairly expensive, and offer slow data speeds.  

While Facebook’s cancelled project comes from the more traditional approach to satellite internet, the current hope of Wyler and other satellite entrepreneurs is that constellations made up of many small satellites could solve those two problems. They would offer faster service, since they are closer to earth than the typical communication satellites, which fly at high altitudes to maximize coverage; and they would cost less, since tiny satellites are typically less expensive than their larger siblings.

But even this plan may over-promise—one of the pioneers of the satellite business, Martin Sweeting, chairman of Surrey Satellite Technology Ltd., compared interest in small satellites to the froth on top of a cappuccino. The technical challenges to flying and operating a full-fledged constellation of them may still prove too difficult to surmount.

Similar to the Titan Aerospace system, project 'Loon' funded by
Google provides network communications systems using high altitude
balloons.

And that explains why mainstream, public tech companies like Google and Facebook have tabled their satellite plans—they are apparently riskier than self-driving cars and virtual reality, to name two experimental areas where these companies are still staking aggressive claims. Google also still owns Skybox, a satellite imaging start-up.

But fear not, internet fans, there are still some businesses that dream of creating real satellite internet, since the potential rewards for success could be quite high. Wyler, the entrepreneur who left Google, founded a new satellite-internet concern, with backing from Qualcomm and Virgin Galactic. Elon Musk’s SpaceX has said it is developing a constellation of small communications satellites of its own. And even Google remains an investor in O3b, the firm using satellites to boost internet access in emerging markets.

Of course, the logic for Google and Facebook remains clear: Increased connectivity around the world means more customers for their products. If another company solves the mystery of satellite internet first—through some combination of cheaper rocket launches and more powerful mini-satellites—expect Facebook and Google to look to the heavens once again.