Keep the shuttle flying: Fwd: Rocket landing experiment on tap after SpaceX cargo launch

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: December 17, 2014 at 7:31:03 PM CST
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: Rocket landing experiment on tap after SpaceX cargo launch

Rocket landing experiment on tap after SpaceX cargo launch
December 17, 2014 by Stephen Clark
An aerial view of SpaceX's rocket landing barge, named the Marmac 300 and unofficially christened the "Autonomous Spaceport Drone Ship." Credit: SpaceX
SpaceX hopes to take a giant leap forward in rocket technology a few minutes after Friday's scheduled launch of a Falcon 9 booster taking up nearly two tons of critical supplies and experiments to the International Space Station.
Burning leftover liquid fuel in its propellant tanks, the Falcon 9 rocket's first stage will fly back to Earth after finishing a nearly three-minute burn to send SpaceX's Dragon commercial cargo craft toward the space station. The descent of the first stage will occur just as the Falcon 9's single-engine upper stage puts the Dragon supply ship into orbit on course for a resupply run to the six-person space station crew.
Friday's launch is scheduled for 1:22 p.m. EST (1822 GMT), roughly the moment the International Space Station's orbital track passes over Cape Canaveral.
The 14-story rocket booster will plunge back through the atmosphere at hypersonic speed, firing a subset of its nine Merlin 1D engines three times to a controlled vertical landing on a barge positioned about 200 miles northeast of the Falcon 9's launch pad at Cape Canaveral.
Other rockets are designed to be expendable and are destroyed during their fall back to Earth.
Nothing like it has ever been tried before. Rocket engineers from several companies — including SpaceX's rocket team — have flown vertical takeoff and landing testbeds on short hops, and the space shuttle's solid rocket boosters parachuted to Earth for retrieval by ships in the Atlantic Ocean.
SpaceX has also flown Falcon 9 boosters to two successful soft water landings in the Atlantic after space launches in April and July.
What SpaceX is trying on Friday's launch is more dicey, and company officials are circumspect when talking about probability of pulling off the feat on the first attempt.
"Returning anything from space is a challenge, but returning a Falcon 9 first stage for a precision landing presents a number of additional hurdles," SpaceX said in a post on its website Tuesday. "At 14 stories tall and traveling upwards of 1300 m/s (2,900 mph), stabilizing the Falcon 9 first stage for reentry is like trying to balance a rubber broomstick on your hand in the middle of a wind storm."
https://www.youtube.com/watch?v=uIlu7szab5I
"It's probably not more than a 50 percent chance or less of landing it on the platform for the first time," said Elon Musk, SpaceX's CEO and chief technology officer, in remarks at a colloquium held in October at the Massachusetts Institute of Technology.
In the long run, Musk says reusing rockets is vital to expanding access to space. He likes SpaceX's chances of achieving an intact landing of a rocket within the next year.
"There are at least a dozen launches that will occur over the next 12 months, and I think it's quite likely — probably 80 to 90 percent likely — that one of those flights we'll be able to land and refly," Musk said. "So I think we're quite close."
After attempts to recover Falcon rockets by parachute failed, SpaceX turned to a propulsive landing concept in which the booster's first stage engines would refire several times in flight to guide the rocket to controlled touchdown.
SpaceX engineers have fine-tuned the descent system's design over the last year.
The first try to land a Falcon 9 rocket stage after a September 2013 launch from Vandenberg Air Force Base in California succumbed to a high roll rate that starved its engines of fuel due to centrifugal forces. Engineers added more powerful nitrogen cold gas thrusters to stabilize the rocket's roll during descent during the next attempt in April, which accomplished a gentle splashdown in the Atlantic Ocean before it crashed on its side and disintegrated.
The next full-up landing test in July — after a launch with six Orbcomm communications satellites — had a similar result.
SpaceX eventually eyes flying its rocket boosters back to their launch sites to permit rapid reuse, but the company indicated in mid-2014 it might try landing a rocket on an ocean-going barge by the end of the year.
In August, SpaceX filed challenges to a patent granted to Blue Origin, a space industry competitor owned by Amazon.com founder Jeff Bezos, describing a concept to land a rocket tail first on an ocean vessel after launching from a shore-based facility.
SpaceX cited previous design work involving sea-based rocket landing pads before Blue Origin applied for the patent in 2009.
"The 'rocket science' claimed in the '321 patent was, at best, 'old hat' by 2009," SpaceX attorneys wrote in one of the patent challenge petitions.
While SpaceX is on the verge of attempting a barge landing, Blue Origin has not disclosed any near-term plans to demonstrate the concept. The first flight of Blue Origin's orbital launch vehicle is years away.
The patent dispute is still unresolved, but SpaceX is pressing ahead with the planned precision landing at sea.
A diagram of rocket recovery at sea from Blue Origin's patent filing. SpaceX is challenging the patent. Credit: Blue Origin
Four carbon fiber and aluminum honeycomb landing legs are mounted at the base of the 12-foot-diameter Falcon 9 first stage. They will deploy to a span of about 70 feet moments before touchdown.
"To help stabilize the stage and to reduce its speed, SpaceX relights the engines for a series of three burns," SpaceX wrote on its website. "The first burn — the boostback burn — adjusts the impact point of the vehicle and is followed by the supersonic retro propulsion burn that, along with the drag of the atmosphere, slows the vehicle's speed from 1300 m/s (2,900 mph) to about 250 m/s (559 mph). The final burn is the landing burn, during which the legs deploy and the vehicle's speed is further reduced to around 2 m/s (4.5 mph)."
The SpaceX landing pad — dubbed the autonomous spaceport drone ship — is officially named the Marmac 300. It is registered under the ownership of Metairie, La.-based McDonough Marine Service and carries ballast water tanks and repurposed underwater thrusters to hold position in the Atlantic Ocean.
The cargo barge was prepared for its rocket landing mission at a Louisiana shipyard, then it moved to a staging point in Jacksonville, Fla.
Photos of the vessel docked at the Port of Jacksonville showed technicians preparing the barge for departure to the Falcon 9 rocket's landing point. Nearby vessels, presumed to be a tug and command ship, also showed signs of rocket-related activity such as the presence of high-tech space communications gear.
See photos of the Marmac 300 and support vessels before they departed Jacksonville.
According to data from the maritime tracking website marinetraffic.com, the Marmac 300's tug and its likely control ship went to sea from Jacksonville on Tuesday.
McDonough Marine Service's website says the Marmac 300 is 300 feet long and 100 feet wide — the size of a football field. Musk tweeted last month the Falcon 9 landing barge has extendable wings to expand the width to 170 feet.
"While that may sound huge at first, to a Falcon 9 first stage coming from space, it seems very small," SpaceX wrote on its website. "The legspan of the Falcon 9 first stage is about 70 feet and while the ship is equipped with powerful thrusters to help it stay in place, it is not actually anchored, so finding the bullseye becomes particularly tricky. During previous attempts, we could only expect a landing accuracy of within 10 km (6 miles). For this attempt, we're targeting a landing accuracy of within 10 meters (32 feet)."
The Marmac 300 is emblazoned with a SpaceX logo in the center of a bullseye painted on a black deck.
For Friday's launch and landing experiment, SpaceX engineers added fins near the top of the Falcon 9's first stage to add stability as the rocket falls back to Earth. The hypersonic grid fins are arranged in an "X-wing" configuration around the circumference of the launcher and remain stowed during liftoff before popping open on reentry.
Hypersonic grid fins were added to the Falcon 9 rocket to stabilize the first stage booster during descent. They will be stowed during launch and will deploy during re-entry. Credit: SpaceX
"Each fin moves independently for roll, pitch and yaw, and combined with the engine gimbaling, will allow for precision landing — first on the autonomous spaceport drone ship, and eventually on land," SpaceX said in its online update Tuesday.
"Before we boost back to the launch site, and try to land there, we need to show that we can land with precision over and over again," Musk said in October. "Otherwise, something bad could happen if it doesn't boost back to where we intended."
If SpaceX returns the rocket to Earth intact, engineers will examine the booster's structure, propellant tanks and engines to determine what work is needed to refurbish the first stage and fly it again.
Musk has said SpaceX's goal is the "rapid and complete" reusability of the Falcon 9's booster stage. He said the rocket's upper section, which enters orbit with each mission's payload, may continue to be a throwaway component of the launcher until a new generation of rockets start flying.
But SpaceX's quest to demonstrate a reusable booster will be restricted to a fraction of the company's launches in the next few years. SpaceX officials say some of their flights, such as Falcon 9 launches with heavy commercial communications satellites and military missions, will not have enough leftover fuel to devote to a guided descent of the rocket.
When the company's Falcon Heavy rocket starts flying — a maiden launch is planned as soon as late next year — more launches will have fuel to spare to get rocket stages back on the ground.
A launch is often one of the most expensive parts of a space mission for human crews, commercial and military satellites, and scientific probes. Saving the rocket booster and launching it repeatedly could dramatically cut the cost of spaceflight, according to SpaceX.
"The reason why there's low demand for spaceflight is because it's ridiculously expensive, and so at some point someone has to say, 'We're going to make something that's much more affordable and then see what applications develop.' That's what has to happen," Musk said.

© 2014 Spaceflight Now Inc.

Photos: SpaceX's autonomous spaceport drone ship
December 16, 2014 by Stephen Clark
An ocean-going cargo barge modified to serve as a landing pad for SpaceX's Falcon 9 booster is set to depart the Port of Jacksonville for a journey into the Atlantic Ocean ahead of Friday's launch of a space station cargo mission from Cape Canaveral.
The barge will be stationed about 200 miles northeast of Cape Canaveral — or about 165 miles southeast of Charleston, S.C. — for Friday's Falcon 9 launch, which is set for 1:22 p.m. EST (1822 GMT). SpaceX hopes to refire engines on the Falcon 9 rocket's first stage after the booster finishes its nearly three-minute burn to propel a Dragon supply ship into orbit on the way to the International Space Station.
While the Falcon 9 rocket's second stage injects the Dragon spacecraft into orbit, a subset of the first stage's nine Merlin 1D engines will reignite to guide the 14-story rocket back to the ground from more than 50 miles in altitude. The rocket will deploy grid fins for aerodynamic stability and then extend four landing legs just before touchdown on the landing ship, which is named the Marmac 300 but has been christened the "Autonomous Spaceport Drone Ship" by SpaceX.
A final landing burn will slow down the rocket for a vertical descent to the ship, which SpaceX founder and CEO Elon Musk says has thrusters repurposed from a deep sea oil drilling rig to keep the barge within 3 meters — about 10 feet — of the correct position.
Emblazoned with a SpaceX logo in the center of a bullseye painted on a black deck, the barge is 300 feet long with extendable wings to stretch its width to 170 feet, according to Musk, who assessed the probability of successfully pulling off an intact recovery of the booster stage as "probably not more than a 50 percent chance."
The experiment is aimed at demonstrating technologies to make the Falcon 9 reusable, an achievement that Musk says would drastically cut launch costs.
A ship seen near the barge moored at the Port of Jacksonville fitted with dish-shaped communications antennas is believed to be accompanying the Marmac 300 barge into the Atlantic Ocean to act as a control vessel.
Credit: Stephen Clark/Spaceflight Now
Credit: Stephen Clark/Spaceflight Now
Credit: Stephen Clark/Spaceflight Now
Credit: Stephen Clark/Spaceflight Now
Credit: Stephen Clark/Spaceflight Now
Credit: Harwood/CBS News
Credit: SpaceX via Elon Musk

© 2014 Spaceflight Now Inc.

AmericaSpace
For a nation that explores
December 16th, 2014
SpaceX to Launch Next Dragon Mission to Space Station on Friday
By Ben Evans

Spectacular view of the CRS-4 Dragon cargo ship, pictured berthed at the Earth-facing (or "nadir") port of the Harmony node in September 2014. Photo Credit: NASA
Almost three months since its last flight and since winning a $2.6 billion slice of NASA's Commercial Crew transportation Capability (CCtCap) "pie," SpaceX—the Hawthorne, Calif.-based launch services company, headed by entrepreneur Elon Musk—stands primed to launch its seventh Falcon 9 v1.1 booster of 2014. Liftoff of the two-stage rocket from Space Launch Complex (SLC)-40 at Cape Canaveral Air Force Station, Fla., is currently scheduled to occur no sooner than 1:20 p.m. EST on Friday, 19 December, whereupon the fifth dedicated Dragon cargo ship will embark on a two-day rendezvous profile to reach the International Space Station (ISS). The spacecraft will deliver more than 3,700 pounds (1,680 kg) of experiments, technology demonstrations, and supplies for the incumbent Expedition 42 crew and will remain berthed at the station for about four weeks.
Although nearly three months have elapsed since the Cape last shook to the roar of the Falcon 9 v1.1's nine Merlin 1D first-stage engines, 2014 has long since shaped up to be the company's most successful year to date. First trialed in June 2010, the Falcon 9 achieved a flight rate of only two missions per annum through the end of 2012, before executing three launches in 2013. These included a Dragon cargo mission to the ISS in March, the maiden voyage of the uprated Falcon 9 v1.1 in September, and SpaceX's first commercial geostationary payload, the SES-8 communications satellite, in December. The latter mission was covered by AmericaSpace's imagery team in an expansive Photo Feature. Having thus picked up the baton, SpaceX continued to run with it and triumphantly delivered a second geostationary satellite (Thaicom-6) into orbit in January 2014, followed by two more Dragon missions to the ISS in April and September.
However, the Falcon 9 v1.1's fortunes proved mixed during a frustrating summer, which saw its Orbcomm OG-2 mission delayed repeatedly, before a successful launch on 13 July. SpaceX also received some criticism from several areas of the media after initially announcing that it would not televise the launch. In the aftermath of the OG-2 flight, a "personal best" was established on 5 August, when another Falcon 9 v1.1 delivered the AsiaSat-8 communications satellite into geostationary transfer orbit, marking the first occasion on which SpaceX had flown twice in as little as three weeks. It also surpassed the company's 2013 record by marking a fourth flight in a single calendar year. This latter achievement was itself broken on 7 September, when another Falcon 9 v1.1 delivered AsiaSat-6 into orbit … and again on 21 September, when the second Dragon cargo mission of 2014 roared perfectly into orbit. With Friday's upcoming flight, SpaceX will close out 2014 by launching a third Dragon within a single calendar year for the first time.
The Falcon 9 v1.1 is powered off the pad by nine Merlin 1D engines, producing a combined yield of 1.3 million pounds (590,000 kg). Photo Credit: John Studwell/AmericaSpace
The SpX-5 mission is the fifth of 12 dedicated Dragon flights, executed under the language of SpaceX's $1.6 billion Commercial Resupply Services (CRS) contract with NASA, signed back in December 2008. Under the provisions of the contract, the company is required to deliver a combined total of 44,000 pounds (20,000 kg) of equipment and supplies to the ISS. Dragon accomplished an initial Commercial Orbital Transportation Systems (COTS) test flight to the station in May 2012, before kicking off the first of its 12 dedicated missions (CRS-1) in October of the same year. Further missions followed in March 2013, April 2014, and September 2014, with the launch of CRS-5 slightly delayed from its original target of no earlier than 16 December, as a result of the juggling of payloads and cargo priorities in the aftermath of Orbital Sciences' Antares explosion and the loss of the ORB-3 Cygnus cargo ship on 28 October.
Assuming that NASA and SpaceX press ahead with the plan to launch SpX-5 on Friday—a decision which is expected to be finalized in a press briefing at the Kennedy Space Center (KSC) on Thursday, 18 December—the weather forecast anticipates mostly cloudy conditions, a 20 percent likelihood of rain, and a 10 percent chance of lightning. The Falcon 9 v1.1 will be transferred to SLC-40 and will undergo a standard "hot-fire" test of the nine Merlin 1D first-stage engines, after which it will be fueled with liquid oxygen and a highly refined form of rocket-grade kerosene (known as "RP-1"). The cryogenic nature of the oxygen, whose liquid state exists within a temperature range from -221.54 degrees Celsius (-368.77 degrees Fahrenheit) to -182.96 degrees Celsius (-297.33 degrees Fahrenheit), requires the fuel lines of the engines to be chilled, in order to avoid thermally shocking or fracturing them. All propellants should be fully loaded within one hour, and at 1:07 p.m. EST Friday the countdown will reach its final "Go-No Go" polling point of all stations at T-13 minutes. Due to the nature of its destination, this launch window will be an "instantaneous" one, with no margin to accommodate technical issues or poor weather. If the vehicle cannot launch on time, the attempt will be scrubbed and the clock recycled.
Passing through the polls at T-13 minutes, the Terminal Countdown will get underway at T-10 minutes. During this phase, the Merlin 1D engines will be chilled, preparatory to their ignition sequence. All external power utilities from the Ground Support Equipment (GSE) will be disconnected, and at 1:15 p.m. EST the roughly 90-second process of retracting the "strongback" away from the vehicle will get underway. The Flight Termination System (FTS), which is tasked with destroying the Falcon 9 v1.1 in the event of a major accident during ascent, will be placed onto internal power and armed.
Experimental landing legs on the SpaceX Falcon-9 v1.1 rocket. Photo Credit: Alan Walters/AmericaSpace
By T-2 minutes and 15 seconds, the first stage's propellant tanks will attain flight pressure. The Merlin 1D engines will be purged with gaseous nitrogen, and at T-60 seconds the SLC-40 complex's "Niagara" deluge system of 53 nozzles will be activated, flooding the pad surface and flame trench with 30,000 gallons (113,500 liters) of water, per minute, to suppress acoustic energy radiating from the engine exhausts. At T-3 seconds, the Merlins will roar to life, ramping up to a combined thrust of 1.3 million pounds (590,000 kg). Following computer-commanded health checks, the stack will be released from SLC-40 to commence SpaceX's seventh and last mission of 2014.
Immediately after clearing the tower, the booster will execute a combined pitch, roll, and yaw program maneuver, which is designed to establish it onto the proper flight azimuth to inject the CRS-5 Dragon spacecraft into low-Earth orbit. Eighty seconds into the climb uphill, the vehicle will exceed the speed of sound and experience a period of maximum aerodynamic duress—colloquially dubbed "Max Q"—on its airframe. At about this time, the Merlin 1D Vacuum engine of the second stage will undergo a chill-down protocol, ahead of its own ignition later in the ascent. At 1:22 p.m. EST, 130 seconds after liftoff, two of the first-stage engines will throttle back, under computer command, in order to reduce the rate of acceleration at the point of Main Engine Cutoff (MECO).
Finally at T+2 minutes and 58 seconds, the seven remaining first-stage engines will be shut down, and, a few seconds later, the lower component of the Falcon 9 v1.1 will separate from the rapidly ascending stack. The turn will then come for the restartable second stage, whose Merlin 1D Vacuum engine—with a maximum thrust of 180,000 pounds (81,600 kg)—will come to life to continue the boost into orbit. Based upon previous Dragon missions, it will burn for about six minutes and 45 seconds to inject the cargo ship into a "parking orbit." During this time, the protective nose fairing, which covers Dragon's berthing mechanism, will be jettisoned. Ten minutes after departing the Cape in a blaze of night and noise, the sixth overall ISS-bound Dragon will separate from the second stage and unfurl its electricity-generating solar arrays, deploy its Guidance and Navigation Control (GNC) Bay Door to expose critical rendezvous sensors, and begin the intricate sequence of maneuvers to reach the ISS on Sunday, 21 December.
In charge of the successful arrival of CRS-5 at the space station are the Expedition 42 crew, commanded by NASA's Barry "Butch" Wilmore, and also consisting of Russian cosmonauts Aleksandr Samokutyayev and Yelena Serova, as well as recent arrivals Anton Shkaplerov, U.S. astronaut Terry Virts and Italy's first woman in space, Samantha Cristoforetti. As part of preparations for Dragon, the crew will install the Centerline Berthing Camera System (CBCS) inside the Earth-facing (or "nadir") hatch of the station's Harmony node and route video equipment to permit imagery to be obtained by the Robotics Workstation (RWS) in the cupola and by Mission Control in Houston, Texas. As with previous Dragons, CRS-5 will approach the ISS along the "R-Bar" (or "Earth Radius Vector"), which provides an imagery line from Earth's center toward the station, effectively approaching its quarry from "below."
The CRS-4 Dragon spacecraft approaches the International Space Station (ISS) for berthing in September 2014. Note the cylindrical, unpressurized "Trunk," equipped with solar arrays and topped by the recoverable cargo capsule. Photo Credit: NASA
In doing so, Dragon will take advantage of natural gravitational forces to provide braking for its final approach and reduce the overall number of thruster firings it needs to perform. By the morning of Sunday, 21 December, it will reach the vicinity of the ISS. A carefully orchestrated symphony of maneuvers will then bring the cargo ship to a "Hold Point" about 1.5 miles (2.4 km) from the space station, whereupon it must pass a "Go-No Go" poll of flight controllers in order to draw closer. Further polls and holds will be made at distances of 3,700 feet (1,130 meters) and 820 feet (250 meters), after which Dragon will creep toward its target at less than 3 inches (7.6 cm) per second.
Critically, at 650 feet (200 meters), it will enter the "Keep-Out Sphere" (KOS), which provides a collision avoidance exclusion zone, and its rate of closure will be slowed yet further to just under 2 inches (5 cm) per second. After clearance has been granted for the robotic visitor to advance to the 30-foot (10-meter) "Capture Point," the final stage of the rendezvous will get underway, bringing Dragon within range of the 57.7-foot-long (17.6-meter) Canadarm2 mechanical arm. Wilmore will be at the controls for the capture and berthing, with Cristoforetti backing him up. Both astronauts will be stationed within the multi-windowed cupola. Following the initial capture of Dragon—an event anticipated to take place at about 6 a.m. EST Sunday—it will be maneuvered to its berthing interface on the nadir port of the Harmony node.
Physical berthing will occur in two stages, with Wilmore's crew overseeing "First Stage Capture," in which hooks from the node's nadir Common Berthing Mechanism (CBM) will extend to snare the cargo ship and pull their respective CBMs into a tight mechanized embrace. "Second Stage Capture" will then rigidize the two connected vehicles, by driving 16 bolts, effectively establishing Dragon as part of the ISS for the next four weeks. Shortly afterwards, the Expedition 42 crew will be given a "Go" to pressurize the vestibule leading from the Harmony nadir hatch into the cargo ship.
Laden with more than 3,700 pounds (1,680 kg) of experiments, technology demonstrations, and supplies—and, doubtless, Christmas gifts for the crew and perhaps birthday presents for Wilmore, who turns 52 on 29 December—the CRS-5 Dragon will support much of the scientific research to be undertaken during Expedition 42. One key payload is NASA's Cloud Aerosol Transport System (CATS), to be installed on the Exposed Facility (EF) of Japan's Kibo laboratory module. This instrument will spend between six months and three years measuring the location, composition, and distribution of pollution, dust, smokes, aerosols, and other particulates in the atmosphere, using Light Detection and Ranging (LIDAR).
The Cloud Aerosol Transport System (CATS) will be robotically attached to the Exposed Facility (EF) of Japan's Kibo laboratory module. It will remain operational for between six months and three years. Photo Credit: SpaceX
Operating at three wavelength bands—at 1,064, 532, and 355 nanometers—the data from CATS will be utilized to explore the properties of cloud and aerosol layers, as well as helping to develop and refine climate models and provide insights for future observations of Mars, Jupiter, and other planetary bodies. In readiness for launch, CATS departed NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Md., on 30 September, bound for SpaceX's facility at Cape Canaveral, for final pre-launch processing. It was installed aboard the unpressurized "Trunk" of the CRS-5 Dragon vehicle on 8 October.
Present plans envisage the spacecraft remaining berthed at the ISS for about four weeks, with its robotic unberthing, departure, and return to Earth anticipated on 19 January. It will be loaded with supplies, hardware, and computer equipment, as well as experiment results, which it will transport back through the atmosphere to a parachute-assisted splashdown off the coast of Baja California. At present, Dragon is the only unpiloted cargo craft capable of returning safely to Earth; by contrast, its partners—Europe's Automated Transfer Vehicle (ATV), Japan's H-II Transfer Vehicle (HTV) "Kounotori" ("White Stork"), Russia's Progress, and Orbital Sciences' Cygnus—are loaded with trash and intentionally incinerated in the dense upper atmosphere.
Of particular significance on the CRS-5 mission is that the launch phase is expected to conclude with an attempt to return the first stage of the Falcon 9 v1.1 rocket to a soft landing on a 300 x 160-foot (90 x 50-meter) floating platform in the Atlantic Ocean. Known as the Autonomous Spaceport Drone Ship (ASDS), this vast barge—whose appearance was revealed by Elon Musk in a tweeted photograph last month—will be unanchored, but is reportedly capable of precisely holding its position to within 10 feet (3 meters), "even in a storm," using Differential Global Positioning System (GPS) hardware and four diesel-powered azimuth thrusters, repurposed from deep-sea oil rigs.
Unsurprisingly, Musk has explained that he anticipates no higher than a 50-50 chance of the first stage making a successful landing on the ASDS on its first attempt. However, if it works as advertised, this will mark the first occasion on which SpaceX has returned its Falcon 9 v1.1 flight hardware from the high atmosphere and landed it smoothly onto a solid surface. The company has performed several water splashdowns between September 2013 and September 2014, with mixed results.
Equipped with four fold-out landing legs—made from carbon-fiber and aluminum honeycomb, weighing 4,400 pounds (2,000 kg) and spanning 60 feet (18 meters) when fully deployed—the 150-foot-tall (46-meter) first stage made its initial attempt to return softly to water during the maiden voyage of the Falcon 9 v1.1 in September 2013. Unfortunately, it experienced an uncontrolled roll during descent, which overwhelmed the capabilities of its attitude-control system to compensate. This forced a planned final "burn" of the center Merlin 1D engine to be shortened, due to the centrifugal effect on propellant against the tank walls, which damaged the baffles and allowed for debris intrusion into the powerplant.
A second attempt during the ascent of the CRS-3 Dragon cargo mission in April 2014 met with greater success, experiencing no spin and zero vertical velocity, as planned. This marked the first successful controlled oceanic touchdown of liquid-fueled orbital booster, but due to rough seas the first stage was not recovered. SpaceX's third attempt took place during the Orbcomm OG-2 ascent in July 2014, and was again successful, although the first stage's hull integrity was breached when it toppled from vertical to horizontal in the Atlantic and it was not retrieved. Most recently, during the CRS-4 Dragon launch in September 2014, another successful splashdown was logged, but again no attempt was made to recover the first stage, as it was known that it would not survive the tip-over from a vertical to a horizontal orientation into the ocean.

Copyright © 2014 AmericaSpace - All Rights Reserved

SpaceX to attempt rocket landing at sea
By Irene Klotz
.
View photo
A Falcon 9 rocket is launched by Space Exploration Technologies on its fourth cargo resupply service …
By Irene Klotz
CAPE CANAVERAL, Fla. (Reuters) - Space Exploration Technologies will attempt to land its Falcon 9 rocket on a sea platform following launch on Friday, company officials said, a vital step to prove its precision landing capabilities needed before it can gain a ground landing license.
SpaceX, as the California-based firm is known, has been working on developing technology to return its rockets intact so they can be refurbished and reflown, dramatically cutting costs.
Falcon rockets practiced ocean touchdowns in September 2013 and twice the following year, demonstrating their ability to relight engines, position nose-up and deploy landing legs. But the rockets toppled over and smashed into the sea. "Returning anything from space is a challenge, but returning a Falcon 9 first stage for a precision landing presents a number of additional hurdles," the company said in a statement.
"At 14 stories tall and traveling upwards of 1,300 miles per second (2,092 km per second), stabilizing the Falcon 9 first stage for reentry is like trying to balance a rubber broomstick on your hand in the middle of a wind storm," SpaceX said.
SpaceX put the odds of success at about 50 percent. "Though the probability of success ... is low, we expect to gather critical data to support future landing testing," it said.
Launch is scheduled for 1:22 p.m. EST from Cape Canaveral Air Force Station in Florida.
After separating from the capsule and the rocket's upper-stage booster, the first stage will attempt to slow its fall back through the atmosphere by relighting its Merlin engines three times and positioning itself using steerable fins.
The landing target is a specially made floating platform that will be positioned in the Atlantic Ocean about 200 miles (322 km) northeast of Cape Canaveral.
Though the barge has thrusters for stability it will not be anchored. "Finding the bullseye becomes particularly tricky," SpaceX said.
(Editing by David Holmes)
Copyright © 2014 Reuters Limited. All rights reserved.

Curiosity Rover Finds Life's Building Blocks on Mars
by Mike Wall, Space.com Senior Writer | December 17, 2014 07:00am ET

NASA's Mars rover Curiosity drilled into this rock target, "Cumberland," during the 279th Martian day, or sol, of the rover's work on Mars (May 19, 2013) and collected a powdered sample of material from the rock's interior.
Credit: NASA/JPL-Caltech/MSSS View full size image

SAN FRANCISCO — NASA's Mars rover Curiosity has found organic chemicals — the carbon-containing building blocks of life — on the Red Planet.
The discovery is not evidence that life exists, or has ever existed, on Mars, researchers stressed. But it does mark the first time that organics have been confirmed inside Red Planet rocks, and it checks off a chief goal of the rover team.
"This is really a great moment for the mission," Curiosity project scientist John Grotzinger, of the California Institute of Technology in Pasadena, said during a news conference Tuesday (Dec. 16) here at the annual fall meeting of the American Geophysical Union (AGU). [The Search for Life on Mars in Photos]
The rover's Sample Analysis at Mars instrument (SAM) detected chlorobenzene and several other chlorine-containing carbon compounds in samples from a rock called "Cumberland," which Curiosity drilled into in May 2013.
SAM uses a tiny oven to cook samples, and then analyzes the gases that waft off. Martian soil and rocks commonly host a chlorine-containing chemical called perchlorate, which can destroy or alter organics during this heating process — a fact that has complicated Curiosity's hunt for life's building blocks.
In late 2012, for example, mission scientists announced that SAM had spotted simple chlorinated organics in samples taken from a different site, called "Rocknest." But they have since determined that this earlier detection probably picked up carbon carried to Mars within SAM.
That's not the case with the more complex chlorobenzene, dichloroethane, dichloropropane and dichlorobutane discovered inside the Cumberland sample, researchers said.
"This is the first in situ detection of organics that are from Mars samples," Caroline Freissinet, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, told Space.com. Freissinet is lead author of the paper detailing the Cumberland results, which has been submitted to the Journal of Geophysical Research.
The apparent ubiquity of perchlorate on Mars makes it tough to know if the original Cumberland sample contained chlorobenzene and the other chlorinated compounds, or some other types of organics. Freissinet, however, is leaning toward the latter explanation.
"Everything is Martian — the chlorine and the carbon — but it's from two different molecules, and it mixed together in the SAM oven," she said.
"The aromatic [carbon] ring was certainly there in some form or another," study co-author and SAM principal investigator Paul Mahaffy, also of NASA Goddard, told Space.com. "That didn't get made in the oven."
At the moment, it's impossible to tell whether the Cumberland organics were produced by living organisms, Grotzinger said. He hopes Curiosity's discovery helps guide the planning effort for NASA's 2020 Mars rover mission, which aims to collect samples for eventual return to Earth.
"Let's get 2020 up there to follow this program of where the best rock materials are to return to Earth," he said.
Curiosity scientists also announced two other big discoveries on Tuesday— the detection of an intriguing and mysterious spike in Mars' atmospheric methane levels in late 2013 through early 2014, and the ratio of hydrogen to deuterium (also known as "heavy hydrogen") in the Cumberland sample, which yields clues about when the Red Planet lost much of its surface water.
Curiosity touched down on Mars in August 2012. It is now exploring the foothills of Mount Sharp, which rises 3.4 miles (5.5 kilometers) into the Red Planet's sky from the center of the huge Gale Crater.

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Curiosity Rover Finds Methane on Mars: What It Could Mean for Life
by Miriam Kramer, Space.com Staff Writer | December 16, 2014 01:35pm ET

NASA's Curiosity rover has recently made a surprising find on Mars that could help scientists get one step closer to figuring out if the Red Planet has ever supported life.
The 1-ton Curiosity rover also discovered a fleeting spike in the levels of methane at its landing site, Gale Crater. Over the course of four measurements in two months on Mars, average methane levels increased 10 fold before quickly dissipating, but the cause of the fluctuation is still unknown.
Researchers are particularly interested in finding methane on alien worlds because living organisms produce an overwhelming amount of the gas on Earth. While finding significant amounts of methane on Mars isn't a sure-fire sign of past or present life — geological processes can also produce the gas — it's still a good starting point, according to many scientists. [The Search for Life on Mars in Photos]
"Right now, it's too much of a single-point measurement for us really to jump to any conclusions," Paul Mahaffy of NASA's Goddard Space Flight Center in Greenbelt, Maryland one of the authors of the new methane study, told Space.com. "So all we can really do is lay out the possibilities. And we certainly should have an open mind. Maybe there are microbes on Mars cranking out methane, but we sure can't say that with any certainty. It's just speculation at this point."
This diagram depicts potential means by which methane might incorporate into Mars' atmosphere (sources) and disappear from the atmosphere (sinks). Image released Dec. 16, 2014.
Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan
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A new baseline
Although methane had been discovered before from space, Curiosity made the first in-situ discovery of rapid changes in methane concentration from the surface of Mars. See how Curiosity found methane on Mars in our full infographic.
Credit: By Karl Tate, Infographics Artist
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The new study, which was published online today (Dec. 16) in the journal Science, also reveals that Curiosity found methane levels in the Martian atmosphere to be, on average, about 0.7 parts per billion.
This level is lower than previous estimates and calculations, but still higher than earlier Curiosity readings of methane published last year. The rover's earlier measurements did not find any trace of methane in the Martian atmosphere; however, scientists found a way to concentrate the rover's samples of the atmosphere, allowing them to get the most recent data about the gas.
The lack of methane measured earlier by Curiosity was disappointing for many scientists because of its potentially damning implication for finding Martian life. But the new measurements could mean there's hope yet.
"The original Science [journal] paper was very negative about there being any credence to large fluctuations in methane," Jan-Peter Muller, an ExoMars and Curiosity team member that isn't directly involved with the new study, told Space.com. "The current paper shows that such conclusions should be taken with a great deal of skepticism until sufficient data has been collected."
Water and spikes in methane
Another study published in Science today also details another exciting Curiosity find on Mars. Using a sample of clay, scientists have measured the hydrogen in the Martian atmosphere about 3 billion to 3.7 billion years ago. The new finding could help pin down when the Red Planet lost its liquid surface water.
NASA officials also announced during a news conference at the meeting of the American Geophysical Union today that Curiosity has measured organic compounds in a rock the rover drilled into on the Martian surface. The molecules could have been delivered to Mars via meteorites, or they could be native to the Red Planet, officials added.
"We will keep working on the puzzles these findings present," John Grotzinger, Curiosity project scientist of the California Institute of Technology in Pasadena, said in a statement. "Can we learn more about the active chemistry causing such fluctuations in the amount of methane in the atmosphere? Can we choose rock targets where identifiable organics have been preserved?"
The momentary spike in the level of methane found in the Martian atmosphere is somewhat puzzling for the scientists who discovered it. Curiosity found that the background level of methane averages out to about 0.7 parts per billion, but the spike brought those levels up to an average of 7 parts per billion, in just 60 Mars days. This is particularly surprising because scientists expect methane on Mars to have a lifetime of about 300 years, much longer than it actually stuck around near Curiosity, according to Christopher Webster, the lead author of the new study. [7 Biggest Mars Mysteries Ever]
Curiosity scientists made their first, surprising measurement of the methane in November 2013, when the gas clocked in at 5.5 parts per billion, Webster said. After about two more weeks, the researchers repeated the measurement with Curiosity's SAM (Sample Analysis at Mars) instrument and found the levels were at 7 parts per billion. They found this same level the next time they measured. The fourth measurement, taken a couple weeks later, came in at 9 parts per billion, but six weeks later the methane levels were back to background levels, according to Webster.
It's possible that a trapped bit of gas set free somewhere near Curiosity caused the increase in methane, scientists speculate. This burp could have created a momentary rise in the methane level around the rover, an increase that dissipated relatively quickly.
"Because of the way it [the methane] behaves, we believe it's a smaller, closer source [rather] than it is a bigger, further away source," Webster told Space.com. "But as far as the source of that methane, we cannot rule out biological activity, whether it's today or in the past, and we cannot rule out geophysical activity."
Other methane measurements
Scientists have seen fluctuations in the level of methane in the Martian atmosphere before, using orbiters and Earth-based means of looking at the planet, said Malynda Chizek Frouard, a Mars methane researcher at New Mexico State University who is unaffiliated with the study. The new data from Curiosity could help create better models of the Martian atmosphere, Chizek Frouard added.
Researchers can now try to "create scenarios where a burst of methane would produce the same sort of variation that they saw in Gale Crater," Chizek Frouard told Space.com.
Webster and his team say it is possible to narrow down the source of the methane further, but Curiosity probably isn't up to the task. Scientists will need new tools at Mars that can probe the planet's thin atmosphere to see what type of methane is present.
Certain isotopes of the gas could indicate that life forms created the methane at some point in Mars' history, while other isotopes would potentially mean that geological forces are responsible for producing the gas.
"This is a big surprise to us," Webster said. "And here we are, writing the next chapter."
Editor's Note: This story was updated at 1:55 p.m. EST (1855 GMT) to include new details.

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