Science Blog 3000

Several big developments have taken place in the fledgling commercial space industry this past week, with big news from both SpaceX and Sierra Nevada Corporation, the builders of the Dream Chaser reusable winged vehicle.

SpaceX sells their first giant rocket

SpaceX announced yesterday that it had signed its first launch contract for the Falcon Heavy, a vehicle that’s still under development. The company plans to test the giant new rocket later this year.

The Falcon Heavy is essentially three Falcon 9 rockets ganged together to create the most powerful rocket since the Saturn V. The launcher’s secret is its cross-feed system, a plumbing arrangement to feed fuel from the two side boosters to the center rocket as they ascend. When the two side boosters separate, the center rocket, now basically a single Falcon 9, continues with a full load of fuel.

Falcon Heavy is rated for 53 metric tons of payload to Low Earth Orbit. The advertised price for a Falcon Heavy brings its cost below $1000 per pound, a milestone that has taken on aspects of the holy grail within the launch industry. SpaceX has already planned for all three lower stages of the Falcon Heavy to be reusable, which would reduce the price even further.

The contract is with Intelsat, the world’s largest satellite company, and represents a major victory for the young launch provider. Intelsat began as a consortium of 11 countries 1964, which cooperated to build a satellite communications network in geosynchronous orbit. The consortium grew to over 100 countries over the next forty years, and was finally privatized in 2001, adopting the name Intelsat after the first satellite it had ever launched.

Neither company has announced which satellite will travel aboard a Falcon Heavy; although there are several candidates,
 

Dream Chaser takes its first test flight

Sierra Nevada Corporation’s air tests of its Dream Chaser crew vehicle would normally have received top billing this week had they not been slightly overshadowed by all the (admittedly historic) Dragon hoopla. According to an article at Parabolic Arc (with great video), residents of Jefferson County near Denver were treated to the sight of a Sikorsky Sky Crane flying the Dream Chaser test hardware above the Broomfield airport on Tuesday. The tests were being done in anticipation of Dream Chaser’s Free Flight Tests later this year.

SNC announced yesterday that Dream Chaser had continued four more of its CCDev2 (Commercial Crew Development Round 2) milestones. The four milestones included testing of the Separation System that releases Dream Chaser from its Atlas V booster, Main Landing Gear Drop Testing, Captive Carry Interface Testing, and the captive carry flight test readiness review. (The actual captive carry is the lift by the Sky Crane.) Evidently after the Captive Carry FTRR Sierra Nevada didn’t waste any time getting the bird into the air. Dream Chaser will soon complete its 18 milestones for this round of NASA’s Commercial Crew competition. The last test is an optional Milestone 19, a free flight test from a carrier aircraft.

The reusable Dream Chaser has the unique ability to return injured astronauts at low accelerations back from a space station. The spacecraft is a reincarnation of NASA’s HL-20 crew vehicle, repackaged with SNC’s hybrid rocket system and modernized electronics. Dream Chaser has blown through its milestones fairly quickly, garnering fans not only for its safety and reusability, but also for its good looks.

A woman who lost the use of her limbs after a devastating stroke nearly 15 years ago has taken a sip of coffee by guiding a robotic arm with her thoughts.

The 58-year-old used a brain implant to control the robot and bring a flask of the coffee to her lips, the first time she had picked up anything since she was paralysed and left unable to speak by a catastrophic brain stem stroke.

Doctors hailed the feat as the first demonstration of an implant that directly controls a reaching and gripping robotic arm by sensing and decoding the patient’s brain signals.

The work is part of a US clinical trial of an experimental implant called BrainGate that doctors see as a first step towards devices that can bypass damage to the nervous system and allow paralysed people to regain control of their limbs or amputees to move prosthetics.

“At the very beginning I had to concentrate and focus on the muscles I would use to perform certain functions,” the woman said. “BrainGate felt natural and comfortable, so I quickly got accustomed to the trial.”

Writing in the journal Nature, researchers described trials in which the woman, known only as S3, and a 66-year-old man referred to as T2, used the implant to control two different designs of robotic arm. The pill-sized device is surgically implanted a few millimetres into the motor cortex on the surface of the brain, where its 96 hair-thin electrodes pick up the patient’s neural activity.

In a series of sessions, the patients learned to control the robot arm and pick up foam balls by imagining moving their own arm and hand. Neither patient could control the robotic arm as well as natural arm movements, but doctors were still delighted with their progress.

“These results are the first peer-reviewed demonstration of a three-dimensional reaching and grasping task using direct brain control of a robotic device,” said Leigh Hochberg, a neuroengineer at Brown University in Rhode Island.

“One of the participants was also able to use the investigational BrainGate system to pick up a bottle of coffee and drink from it. This was the first time in nearly 15 years that she had been able to pick up anything solely of her own volition. The smile on her face when she did this is something that I and our whole research team will never forget,” he added.

The man who took part in the trial had a brain stem stroke in 2006. Describing the experience afterwards – by spelling out letters with his gaze – he said: “I just imagined moving my own arm and [the robotic] arm moved where I wanted it to go.”

The BrainGate device plugs directly into the brain, but protrudes through the skull where it is connected to a computer by a cable. More advanced devices are planned that can operate wirelessly and be implanted out of sight, beneath the skin.

NASA’s aeronautical innovators are one step closer to confidently crafting a viable commercial airliner that can fly faster than the speed of sound, yet produce a sonic boom that is quiet enough not to bother anyone on the ground below. 

The key to this recent advance came when wind tunnel tests of scale model airplanes verified that new approaches to designing such aircraft would work as hoped for when aided by improved computer tools, which were used for the first time together in each step of the design process. 

“That was really the breakthrough for us. Not only that the tools worked, but that our tests show we could do even better in terms of reducing noise than we thought at the start of the effort,” said Peter Coen, NASA’s supersonic project manager at Langley Research Center in Virginia. 

Nuisance noise generated by a commercial supersonic jet’s sonic booms during cruise, and by its powerful engines at takeoff and landing, has kept the speedy aircraft from entering service in the United States – except for Europe’s Concorde, which was limited to trans-Atlantic flights only. 

Using the computer tools, teams led by Boeing and Lockheed Martin, and funded through a NASA Research Announcement, came up with designs for two small supersonic airliners that would carry between 30 and 80 passengers and potentially enter service in the 2025 timeframe. 
“In bringing their design expertise to the process, these companies are not only addressing the low boom design elements, but all of the other aspects necessary for a realistic design,” Coen said. 

For example, the computer tools show that one way to reduce the perceived loudness of a supersonic jet’s sonic boom is to change the aircraft shape, in part, by lengthening the aircraft’s fuselage, making it much more slender. Theoretically, the noise issue could be solved by a really, really long aircraft body. 
Unfortunately, while an 800-foot-long airliner may lead to publicly acceptable sonic booms, an aircraft that size still must fit at its gate, make turns while taxiing to the runway without hitting anything and generally not require an expensive redesign of the nation’s airports. 

“The long skinny fuselage is not a practical answer. In our pursuit of boom reductions, we examine the whole, three-dimensional shape of the vehicle including the engine configuration,” Coen said. “Even then, we keep in mind that the airliner has to meet all of the other requirements which are part of good design practice.” 
To help reach their goals, the engineers relied on earlier studies that revealed how an aircraft’s overall configuration could modify the shape of the supersonic shockwaves coming off the airplane so that the atmosphere then reduces the sharpness of the wave. By the time the shockwave reached the ground the shock would be removed, resulting in a nearly inaudible sonic boom. 

“The booms are still there, but your ear is tricked into hearing a thump,” Coen said. 
Two other design considerations are important. The first reduces the size of the proposed commercial airliner so it carries fewer passengers and is lighter. The second slows the cruising speed. While the Concorde cruised at twice the speed of sound, or Mach 2.0, this airliner would cruise at a slightly slower Mach 1.6 to Mach 1.8. 

“These design choices not only made both the sonic boom problem easier to tackle, but make the takeoff and landing noise problem much more solvable, much more amenable to solutions with the technologies we have in hand,” Coen said. 
So how loud was the Concorde and how does that relate to NASA’s goals of making a quieter supersonic airplane? 

The measurement NASA researchers are using to base their work on is called perceived decibel level, or PLdB. Like comparing apples and oranges, PLdB is a different flavor of decibels than the measurement (dBA) often quoted when discussing how loud, for example, a rock concert is compared to a kitchen blender or library reading room. 

Concorde’s sonic boom noise level was 105 PLdB. The PLdB that researchers believe will be acceptable for unrestricted supersonic flight over land is 75, but NASA wants to eventually beat that and reach 70 PLdB. 
“For this phase of the research, we did succeed in reducing the perceived noise level. In fact, one of the designs reached as low as 79 PLdB,” Coen said. “It was a really big step, but we still have some more work to do to reach our ultimate goal of about 70 PLdB.” 

Additional studies already are under way to keep whittling away at the supersonic noise challenge and come up with solutions that will be acceptable to regulatory agencies such as the Federal Aviation Administration, as well as airplane manufacturers, the airlines and the general public. 
And while a commercial supersonic airliner flying from New York to Los Angeles over the U.S. heartland may be another decade or two away, Coen said it’s very possible that smaller supersonic business jets could debut in the skies much sooner because lighter aircraft create weaker shock waves, which makes the low boom design challenge easier to solve. 

“The business jet would probably be the first on the market, and that would help introduce some of the technologies that eventually would be used on the supersonic airliner. But such product decisions belong to others outside of NASA,” Coen said. “Our job is to support the science and technology behind those choices, eventually making supersonic flight available to the traveling public.” 

The sun is moving through the Milky Way slower than previously thought, according to new data from a NASA spacecraft.

From its orbit around Earth, the Interstellar Boundary Explorer (IBEX) satellitemeasured the speeds of interstellar particles entering at the fringes of our solar system, 9 billion miles (14.5 billion kilometers) from the sun.

Plugging the new data into computer models, the IBEX team calculates that the sun is moving at about 52,000 miles (83,700 kilometers) an hour—about 7,000 miles (11,000 kilometers) slower than thought.

NASA’s Mars Reconnaissance Orbiter (MRO) has revealed that movement in sand dune fields on the Red Planet occurs on a surprisingly large scale, about the same as in dune fields on Earth. This is unexpected because Mars has a much thinner atmosphere than Earth, is only about one percent as dense, and its high-speed winds are less frequent and weaker than Earth’s.

For years, researchers debated whether or not sand dunes observed on Mars were mostly fossil features related to past climate, rather than currently active. In the past two years, researchers using images from MRO’s High Resolution Imaging Science Experiment (HiRISE) camera have detected and reported sand movement.

Now, scientists using HiRISE images have determined that entire dunes as thick as 200 feet are moving as coherent units across the Martian landscape. The study was published online today by the journal Nature.

“This exciting discovery will inform scientists trying to better understand the changing surface conditions of Mars on a more global scale,” said Doug McCuistion, director of NASA’s Mars Exploration Program in Washington. “This improved understanding of surface dynamics will provide vital information in planning future robotic and human Mars exploration missions.”

Researchers analyzed before-and-after images using a new software tool developed at the California Institute of Technology (Caltech) in Pasadena. The tool measured changes in the position of sand ripples, revealing the ripples move faster the higher up they are on a dune.

The study examined images taken in 2007 and 2010 of the Nili Patera sand dune field located near the Martian equator. By correlating ripples’ movement to their position on the dune, the analysis determined the entire dunes are moving. This allows researchers to estimate the volume, or flux, of moving sand.

“We chose Nili Patera because we knew there was sand motion going on there, and we could quantify it,” said Nathan Bridges, a planetary scientist at Johns Hopkins University Applied Physics Laboratory in Laurel, Md., and lead author of the Nature paper. “The Nili dunes also are similar to dunes in places like Antarctica and to other locations on Mars.”

The study adds important information about the pace at which blowing sand could be actively eroding rocks on Mars. Using the new information about the volume of sand that is moving, scientists estimate rocks in Nili Patera would be worn away at about the same pace as rocks near sand dunes in Antarctica, where similar sand fluxes occur.

“Our new data shows wind activity is indeed a major agent of evolution of the landscape on Mars,” said Jean-Philippe Avouac, Caltech team leader. “This is important because it tells us something about the current state of Mars and how the planet is working today, geologically.”

Scientists calculate that if someone stood in the Nili Patera dunes and measured out a one-yard width, they would see more than two cubic yards of sand pass by in an Earth year, about as much as in a children’s sand box.

“No one had estimates of this flux before,” said Bridges. “We had seen with HiRISE that there was dune motion, but it was an open question how much sand could be moving. Now, we can answer that.”

Scientists will use the information to understand broader mysteries on Mars, like why so much of the surface appears heavily eroded, how that occurred, and whether it is a current process or it was done in the past. Scientists can now point to sand flux as a mechanism capable of creating significant erosion today on the Red Planet.

The HiRISE camera provides unprecedented resolution in studying the Martian landscape. NASA’s Jet Propulsion Laboratory manages MRO for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space Systems, Denver, built the spacecraft. HiRISE is operated by the University of Arizona and was built by Ball Aerospace & Technologies Corp., Boulder, Colo.

For related images and more information about MRO, visit: http://www.nasa.gov/mro