SpaceX Video Shows Events Leading to Falcon 9 Booster Crash Landing

As reported by SpaceFlight101: Stunning aerial imagery released by SpaceX on Tuesday shows how close the company came to successfully landing the first stage of its Falcon 9 rocket on a floating platform in the Atlantic Ocean in the continuing quest towards reusability of boosters to significantly cut the cost of access to space. 

The short video and a few still frames released by SpaceX show the stage coming in for a landing under the power of one of its engines, but encountering some instability in the last seconds of its descent that led to the stage tipping over after landing on the Autonomous Spaceport Drone Ship (ASDS).

Falcon 9 made a thundering blastoff from Space Launch Complex 40 at Cape Canaveral Air Force Station at 20:10:41 UTC on Tuesday, lofting the Dragon SpX-6 spacecraft into orbit for SpaceX’s sixth operational cargo mission to the International Space Station. Rising with a total thrust of 600,000 Kilogram-force, Falcon quickly ascended and picked up speed, passing Mach 1 just 70 seconds into the flight when the vehicle had aligned itself with its north-easterly flight path, departing Florida’s Space Coast.

The first stage operated for two minutes and 38 seconds. Shutting down its engines, the stage made a clean separation from Falcon’s upper stage that headed on towards orbit, releasing the Dragon spacecraft into its intended trajectory ten minutes and 11 seconds after launch. By then, all the action involving the first stage had already been over and the majority of the stage was on its way to the bottom of the Ocean.

With the second stage heading off into orbit, the first stage booster embarked on its ambitious return. This was the seventh attempt to either soft land a stage in the ocean or return it to the Autonomous Spaceport Drone Ship, it was the third attempted drone ship landing.

The first attempt, on the SpX-5 mission in January, ended in a spectacular crash landing of the booster on the platform after running out of hydraulic fluid in its grid-fin system thus partly using its control authority during final descent. The second try achieved a soft splashdown in the ocean after the ASDS had to be moved out of the way due to extreme sea conditions. However, both of these return attempts showed that the booster could find its way back to the Drone Ship that – in the vastness of the Atlantic – looks extremely tiny when trying to aim for it from 80 Kilometers up.

Equipped with Nitrogen cold gas thrusters, four aerodynamic grid fins and four deployable landing legs, the 43-meter long first stage started out on its journey immediately after stage separation – firing its thrusters to maneuver out of the exhaust of the second stage and re-orient to an engines-forward posture for the first of three propulsive maneuvers – starting out at an altitude of close to 80 Kilometers and a speed of over 2 Kilometers per second at separation.

Real-time call-outs made by the Launch Control Team confirmed that the booster successfully ignited three of its Merlin 1D engines at around T+4 minutes & 30 seconds – each delivering up to 66,700 Kilogram-force of thrust. This retrograde boost-back burn aimed to reduce the downrange travel distance of the first stage by about 50%, compared with a fully ballistic path not including any maneuvers after separation. The boost back burn also modified the exospheric trajectory of the stage, pushing the apogee below 125 Kilometers.

After 30 seconds, the booster shut down its engines again and entered a short ballistic segment, controlling its orientation with the Nitrogen thrusters installed near the interstage in the upper portion of the stage.
Approaching the dense atmosphere, Falcon 9 deployed its four hydraulic grid fins, also located in the interstage section, capable of individually rotating and tilting to provide a great deal of control once entering the discernible atmosphere. The addition of the grid fins improved the landing accuracy of the Falcon 9 from a few kilometers to a few meters, illustrating their importance in the atmospheric segment of flight when the engines are not firing. 

With the fins deploying at T+6 minutes and 30 seconds, the booster was already close to the atmosphere, passing 70 Kilometers in altitude at around T+6:45 – coinciding with the ignition of three M1D engines for the ~17-second Re-Entry Burn. This Supersonic Retropropulsion Burn served two purposes, it began the process of slowing the booster from 1,200m/s and it also protected the engine compartment from the most turbulent region of the re-entry environment. Despite using shielding material in the engine compartment, the re-entry burn is needed to guarantee the intact survival of main propulsion system components for a safe re-use.

Once in the dense atmosphere, the booster transitioned control to the four grid fins with the thrusters complementing the fins whenever needed, particularly for roll control. The four fins can be individually controlled in a two-degree of freedom type design, allowing for complex guidance and control during atmospheric flight.

Heading into the atmosphere, the booster was kept in a stable posture by its low center of mass with the heavy engines in the aft and the nearly empty propellant tanks atop. The grid fins were to provide attitude control, constantly adjusting the pitch trim of the booster to control its along-track travel distance as the stage homed in on the 91 by 52-meter drone ship that precisely held its assigned position by processing GPS data and using its four diesel-powered azimuth thrusters.

Grid Fins & Landing Legs

At T+7 minutes and 47 seconds, it was reported that the first stage had again passed the sound barrier, just the other way around, transitioning from supersonic to subsonic speeds. Just after passing the T+8 minute mark, the first stage ignited its Center Engine to begin the final phase leading up to landing.

The call of ‘Landing Burn Start’ was the final event confirmed through Stage 1 Telemetry as the booster went below the horizon as seen from tracking stations at Cape Canaveral. Ten seconds prior to touchdown, the four landing legs were deployed using pressurized Helium to extend the legs to their deployed position. Landing was planned to occur at a speed of less than 6m/s under the power of the center engine creating a thrust to weight ratio greater than one. Touchdown on the platform had to be perfect, a non-vertical, partial or off-target landing would result in the stage tipping over, falling into the ocean or another undesired outcome.

In one of the NASA Management Rooms, a live feed of low frame-rate video from the ASDS could be seen, showing the first stage coming in to land, but not sticking the landing for some reason.

Using imagery from the ship for a quick analysis of the situation, SpaceX CEO and Chief Designer Elon Musk came to the conclusion that “excess lateral velocity caused it [the booster] to tip over post landing.” Musk’s Tweet was accompanied by two still frames, the first showing the booster with its deployed landing legs and running engine just a few meters above the bullseye target on the deck of the ASDS, the second showing smoke, fire and the stage at an angle, in the process of tipping over.

A few hours after the failed landing attempt, SpaceX posted a short video clip from an airborne drone or hexacopter that flew at some distance to the Drone Ship and recorded the final spectacular seconds of the flight.

The video shows the first stage incoming in a nearly perfectly vertical posture, but descending with a horizontal velocity component that would have likely caused it to overshoot the landing platform. Moments later, gimbaling action on the center engine begins to correct to flight path. At this stage of flight, with the stage at relatively low speed and the engine running, gimbaling of said engine provides the majority of control with the grid fins and thrusters assisting as needed in pitch and yaw control – they are still in charge of roll control.

Image: Spaceflight101/SpaceX

Photo: SpaceX/Elon Musk

Photo SpaceX/Elon Musk

To make the correction of its along-track landing position, already very close to the platform, the stage is tilted through the thrust vector control of the engine, raising some water next to the ASDS. Unfortunately, the stage makes a rather large over-correction that it then attempts to compensate by reversing the tilt on the stage to fly back into the forward direction (oscillations induced by lag between actuator motion and GNC measurements on rockets are certainly not unheard of). At that time, the stage ran out of altitude and made contact with the deck of the landing platform at a pitch angle and lateral velocity that caused it to tip over. The cold gas thrusters can be seen in the short video as the stage desperately tries to come to an upright landing in the center of the platform.

What caused the disturbance that led the stage to drift on a trajectory overshooting the ASDS is not precisely known – possible reasons can include the stage being delivered off target to the landing burn ignition point, a systems malfunction in the last seconds of flight or an external factor such as wind followed by an over-correction of the stage.

Elon Musk later Tweeted that "the issue was stiction in the biprop throttle valve, resulting in control system phase lag." This indicates that the Center Engine was not fast enough in completing what was asked from it by the control system in the critical last seconds of the descent.

It has to be noted that the entire return sequence of the first stage leaves only very little margin for correction. Overall, the sequence from stage separation to landing uses up approximately 10% of the booster’s total propellant load with only two or three seconds of margin, underlining that events of the landing sequence must occur very close to the prediction, providing only very little margin to account for external factors such as wind disturbance.

Photo: SpaceX

The hoverslam landing approach does not help either since no period of hover or constant-velocity descent can be dynamically used to correct for misaligned landings.

SpaceX engineers will be able to retrieve a complete set of telemetry from the stage - from liftoff through the seconds after making contact with the ASDS to piece together the precise inputs of the Guidance System and the outputs of the various actuators (thrusters, fins & engines) to identify any weaknesses, also pulling weather sensor data from the ASDS to look whether an unfortunate gust of wind was responsible.

SpaceX certainly has their work cut out for them, looking at the task of refining the terminal landing algorithm and ensuring the potential throttle valve condition will not occur again. This landing attempt provided them with plenty of data that will be applied to solving the issues seen on Tuesday and increase the odds of achieving a successful landing on the Autonomous Spaceport Drone Ship in June on the Dragon SpX-7 mission.

Falcon 9 may also be looking forward to its first return to a land-based pad in July on the Jason-3 mission out of Vandenberg where construction of the landing pad at Space Launch Complex 4W has made progress over the past months.

The Autonomous Spaceport Drone Ship will return to the Port of Jacksonville in the coming days and bring home any components of Falcon 9 that may have ended up on deck.

SpaceX Rocket Launched Successfully, Landed 'Too Hard for Survival'

As reported by Engadget: Today SpaceX successfully launched its latest mission to the International Space Station, but couldn't reach its goal of safely landing the rocket's first stage on a barge. According to CEO Elon Musk, while the ascent was successful, the "Rocket landed on droneship, but too hard for survival." There's no video of the landing attempt yet, but hopefully soon we'll be able to see how close it came. This outcome isn't entirely unexpected either, as Musk tweeted yesterday that the chance of a successful landing by the end of the year stands as high as 80 percent, only because the company has so many launches planned.


Broadcast live streaming video on Ustream

This is the sixth of at least 12 cargo deliveries covered by a $1.6 billion contract between SpaceX and NASA. The mission's prime objective is to transport more than 4,300 pounds (1,950 kilograms) of supplies and payloads, including the first zero-G espresso machine to go into orbit.

The Italian-built ISSpresso device was supposed to be delivered to the space station in January, but the loss of an Orbital Sciences shipment in October forced a reordering of the delivery schedule.

NASA's deputy manager for the space station program, Dan Hartman, said the fancy coffeemaker is a commercial experiment that the space agency hopes will "boost spirits" during long-duration space missions.      

Try, try again

SpaceX was also looking for a boost in its effort to make rockets reusable and drive the cost of spaceflight dramatically downward.

In January, an earlier Falcon 9 found its way to the deck — but the control system ran out of hydraulic fluid prematurely. As a result, the stage came down crooked and blew apart in a fiery blast. A second landing opportunity, in February, turned into an ocean splashdown test when SpaceX determined that the seas were too rough to use the platform.   

NASA Made an Autonomous Car Too, and it Makes Google’s Look Dull

As reported by SlashGear: Auto makers the world over are scrambling to create cars that can drive themselves, but they're not the only ones interested in such technology. NASA has set its sights on the technology, something we've heard bits and pieces about in the past. Today the space agency decided to show the fruits of its labor, however, posting a video on its YouTube account of the finished product. It is called the Modular Robotic Vehicle, MRV for short, and it can -- among other things -- drive itself when needed.

The car is about the size of a golf cart, and it has many features, not the least of which is both remote and autonomous control — you can see an example of the remote control feature in the video below, where the driver moves over to the passenger seat and is taken for a ride.

The vehicle itself is electric and powered by batteries, and it includes a full drive-by-wire system, as well as redundant fail-operational architecture, and most interestingly, all four of its wheels are independent modules, able to rotate in such ways that the car can out maneuver any average road vehicle.

According to NASA, the MRV shown above has a top speed of 40MPH, but it is currently computer limited to only 15MPH, likely for safety reasons. The curb weight is 2000lbs, and it measures in at 7ft. x 5ft. The propulsion motors in the wheels are cooled with liquid, meanwhile. The MRV was made at NASA’s Johnson Space Center.

A highly redundant version with 12 wheels, active suspension, and agile steering.

Amazon Gets Green Light from U.S. Regulators for New Drone Tests

As reported by Reuters:  Amazon.com Inc has won approval from U.S. federal regulators to test a delivery drone outdoors, less than a month after the e-commerce powerhouse blasted regulators for being slow to approve commercial drone testing.

The Federal Aviation Administration had earlier given the green light to an Amazon prototype drone in March, but the company told U.S. lawmakers less than a week later that the prototype had already become obsolete while it waited more than six months for the agency's permission.  

The FAA granted Amazon's request to test delivery drones in a letter dated Wednesday, posted on the agency's website.

Amazon must keep flights at an altitude of no more than 400 feet (120 meters) and no faster than 100 miles per hour (160 km per hour), according to the letter.

Seattle-based Amazon.com has been pursuing its goal of sending packages to customers by air, using small, self-piloted aircraft, even as it faces public concern about safety and privacy.  

The company wants to use drones to deliver packages to its customers over distances of 10 miles (16 km) or more, which would require drones to travel autonomously while equipped with technology to avoid collisions with other aircraft.
  

In February, the FAA proposed long-awaited rules to try to set U.S. guidelines for drones, addressing growing interest from both individual and corporations in using unmanned aerial vehicles.

Amazon did not immediately respond to requests for comment.

SpaceX Launch Today: Space Station Supplies and Another Booster Landing Attempt

As reported by Slate: SpaceX is scheduled to launch a Falcon 9 rocket today (now rescheduled for Tuesday 04/14/2015) at 20:33 UTC (4:33 p.m. Eastern) from Florida. The primary goal: Send a Dragon capsule loaded with two tons of supplies to the International Space Station. The secondary one: Land the first stage booster on a barge floating in the Atlantic Ocean.

First things first. If you want to watch the launch live, try the SpaceX webcast page, NASA’s Ustream channel, or NASA TV.

I suspect most people will be most interested in the booster landing attempt. The Falcon 9 rocket has two stages. Every kilo you send to orbit means you need fuel to lift it, so many rockets use staging to save fuel; the heavy bottom half is jettisoned at some point, carving a lot of weight off the rocket.

Usually the first stage is discarded; dropping into a watery grave in the ocean or burning up on re-entry. But SpaceX wants to save money by reusing that booster stage. The Falcon 9 booster saves just enough fuel to slow down after the initial launch (and the second stage is safely away). It then drops down, deploys fins on the bottom to help steer it, and—should all go well—lands vertically on a floating platform (technically, the autonomous spaceport drone ship; it has onboard computers that allow it to position itself under the returning booster automatically).

SpaceX tried this in January, with, um, less-than-perfect results. That was due to the fins running out of hydraulic fluid while the booster was still aloft, a shortcoming that has been corrected. This second attempt^* will hopefully go better. Mind you, in that first attempt the booster slowed and descended correctly, the barge positioned itself, and everything went right except for the one (catastrophic) problem. Fixing that should go a long way to a successful landing.

If it works, it will be the first time in history a booster will have been recovered in this way.

Let's hope that it goes better this time.

The main mission is to get a Dragon capsule to ISS. This mission, Commercial Resupply Service 6 (or just CRS-6), will deliver cargo and supplies to the crew on the station. One piece of hardware going up in the Dragon is the Arkyd 3 Reflight, a very small satellite by the company Planetary Resources that will test technology that will be used in future asteroid reconnaissance missions.

Right now, the weather for the afternoon is iffy. If the launch is scrubbed, a second attempt will be made Tuesday at 20:10 UTC (4:10 p.m. Eastern).

Incidentally, SpaceX recently released a bunch of super-hi-res footage of launches and landings from previous missions. It’s pretty cool. This should keep you sated until this next launch.

^*Kinda sorta second, that is; during a February launch the ocean was too rough to land on the barge, so SpaceX landed the booster vertically in the ocean. I consider that a practice run.

Aston Martin is Developing a Plug-in Hybrid and an Electric Vehicle

As reported by Engadget: If you've ever wanted to feel like a more eco-friendly Bond behind the wheel, then Aston Martin is about to make your dreams come true. The automaker has revealed at the New York Auto Show that it's working on both a plug-in and an electric vehicle. That plug-in is none other than the DBX crossover vehicle (pictured above) that we saw in early March as a full electric car. Unlike the concept showcased in Geneva, it will have four doors instead of two; plus, the automaker's still adjusting its overall dimensions to make it roomier inside. While it will debut as a plug-in, CEO Andy Palmer says that if the company proves electric works, then it "would be a nice place to go."

That means the EV currently under development is another model altogether, and according to Palmer, it's an electric version of Aston Martin's four-door, family-friendly Rapide S. The company has recently begun the technical study of a pure-electric Rapide, which it wants to equip with components that will give it a (whopping!) 1,000-horsepower capability. Palmer said the all-electric Rapide S will be available in two years' time, but he didn't mention when the plug-in DBX might come out. He did say that the hybrid will carry a price tag similar to a regular Rapide, so ready your bank accounts, because that's around $200,000. 

Electromagnetic Breakthrough: Scientists Design Antenna ‘on a Chip’

Anechoic test chamber.  University of Cambridge.

As reported by Phys.org: A team of researchers from the University of Cambridge have unraveled one of the mysteries of electromagnetism, which could enable the design of antennas small enough to be integrated into an electronic chip. These ultra-small antennas - the so-called 'last frontier' of semiconductor design - would be a massive leap forward for wireless communications.

WiFi antenna etched on a printed circuit board.

In new results published in the journal Physical Review Letters, the researchers have proposed that electromagnetic waves are generated not only from the acceleration of electrons, but also from a phenomenon known as symmetry breaking. In addition to the implications for wireless communications, the discovery could help identify the points where theories of classical electromagnetism and quantum mechanics overlap.

The phenomenon of radiation due to electron acceleration, first identified more than a century ago, has no counterpart in quantum mechanics, where electrons are assumed to jump from higher to lower energy states. These new observations of radiation resulting from broken symmetry of the electric field may provide some link between the two fields.

Dipole antenna radiation pattern.

The purpose of any antenna, whether in a communications tower or a mobile phone, is to launch energy into free space in the form of electromagnetic or radio waves, and to collect energy from free space to feed into the device. One of the biggest problems in modern electronics, however, is that antennas are still quite big and incompatible with electronic circuits - which are ultra-small and getting smaller all the time.

"Antennas, or aerials, are one of the limiting factors when trying to make smaller and smaller systems, since below a certain size, the losses become too great," said Professor Gehan Amaratunga of Cambridge's Department of Engineering, who led the research. "An aerial's size is determined by the wavelength associated with the transmission frequency of the application, and in most cases it's a matter of finding a compromise between aerial size and the characteristics required for that application."

Another challenge with aerials is that certain physical variables associated with radiation of energy are not well understood. For example, there is still no well-defined mathematical model related to the operation of a practical aerial. Most of what we know about electromagnetic radiation comes from theories first proposed by James Clerk Maxwell in the 19th century, which state that electromagnetic radiation is generated by accelerating electrons.

However, this theory becomes problematic when dealing with radio wave emission from a dielectric solid, a material which normally acts as an insulator, meaning that electrons are not free to move around. Despite this, dielectric resonators are already used as antennas in mobile phones, for example.

Dialectric patch antennas are already in use by GPS devices.

"In dielectric aerials, the medium has high permittivity, meaning that the velocity of the radio wave decreases as it enters the medium," said Dr Dhiraj Sinha, the paper's lead author. "What hasn't been known is how the dielectric medium results in emission of electromagnetic waves. This mystery has puzzled scientists and engineers for more than 60 years."

Working with researchers from the National Physical Laboratory and Cambridge-based dielectric antenna company Antenova Ltd, the Cambridge team used thin films of piezoelectric materials, a type of insulator which is deformed or vibrated when voltage is applied. They found that at a certain frequency, these materials become not only efficient resonators, but efficient radiators as well, meaning that they can be used as aerials.

The researchers determined that the reason for this phenomenon is due to symmetry breaking of the electric field associated with the electron acceleration. In physics, symmetry is an indication of a constant feature of a particular aspect in a given system. When electronic charges are not in motion, there is symmetry of the electric field.

Micro antenna

Symmetry breaking can also apply in cases such as a pair of parallel wires in which electrons can be accelerated by applying an oscillating electric field. "In aerials, the symmetry of the electric field is broken 'explicitly' which leads to a pattern of electric field lines radiating out from a transmitter, such as a two wire system in which the parallel geometry is 'broken'," said Sinha.

The researchers found that by subjecting the piezoelectric thin films to an asymmetric excitation, the symmetry of the system is similarly broken, resulting in a corresponding symmetry breaking of the electric field, and the generation of electromagnetic radiation.
The electromagnetic radiation emitted from dielectric materials is due to accelerating electrons on the metallic electrodes attached to them, as Maxwell predicted, coupled with explicit symmetry breaking of the electric field.

"If you want to use these materials to transmit energy, you have to break the symmetry as well as have accelerating electrons - this is the missing piece of the puzzle of electromagnetic theory," said Amaratunga. "I'm not suggesting we've come up with some grand unified theory, but these results will aid understanding of how electromagnetism and quantum mechanics cross over and join up. It opens up a whole set of possibilities to explore."

Si doped 4 inch VGF-GaAs crystal grown in HMM

The future applications for this discovery are important, not just for the mobile technology we use every day, but will also aid in the development and implementation of the Internet of Things: ubiquitous computing where almost everything in our homes and offices, from toasters to thermostats, is connected to the internet. For these applications, billions of devices are required, and the ability to fit an ultra-small aerial on an electronic chip would be a massive leap forward.

Piezoelectric materials can be made in thin film forms using materials such as lithium niobate, gallium nitride and gallium arsenide. Gallium arsenide-based amplifiers and filters are already available on the market and this new discovery opens up new ways of integrating antennas on a chip along with other components.

"It's actually a very simple thing, when you boil it down," said Sinha. "We've achieved a real application breakthrough, having gained an understanding of how these devices work."