Pentagon releases results of 13000-mph test flight over Pacific – Los Angeles Times

An artist’s rendering of the Falcon Hypersonic Technology Vehicle 2. (Defense Advanced Research Projects Agency / April 20, 2012)

The results are in from last summer’s attempt to test new technology that would provide the Pentagon with a lightning-fast vehicle, capable of delivering a military strike anywhere in the world in less than an hour.

In August the Pentagon’s research arm, known as the Defense Advanced Research Projects Agency, or DARPA, carried out a test flight of an experimental aircraft capable of traveling at 20 times the speed of sound.

The arrowhead-shaped unmanned aircraft, dubbed Falcon Hypersonic Technology Vehicle 2, blasted off from Vandenberg Air Force Base, northwest of Santa Barbara, into the upper reaches of the Earth’s atmosphere aboard an eight-story Minotaur IV rocket made by Orbital Sciences Corp.

After reaching an undisclosed altitude, the aircraft jettisoned from its protective cover atop the rocket, then nose-dived back toward Earth, leveled out and glided above the Pacific at 20 times the speed of sound, or Mach 20.

The plan was for the Falcon to speed westward for about 30 minutes before plunging into the ocean near Kwajalein Atoll, about 4,000 miles from Vandenberg.

But it was ended about nine minutes into flight for unknown reasons. The launch had received worldwide attention and much fanfare, but officials didn’t provide much information on why the launch failed.

On Friday, DARPA said in a statement that the searing high speeds caused portions of the Falcon’s skin to peel from the aerostructure. The resulting gaps created strong shock waves around the vehicle as it traveled nearly 13,000 mph, causing it to roll abruptly.

The Falcon, which is built by Lockheed Martin Corp., is made of durable carbon composite material, which was expected to keep the aircraft’s crucial internal electronics and avionics — only a few inches away from the surface — safe from the fiery hypersonic flight. Surface temperatures on the Falcon were expected to reach more than 3,500 degrees, hot enough to melt steel.

“The initial shock wave disturbances experienced during second flight, from which the vehicle was able to recover and continue controlled flight, exceeded by more than 100 times what the vehicle was designed to withstand,” DARPA Acting Director Kaigham J. Gabriel said in a statement. “That’s a major validation that we’re advancing our understanding of aerodynamic control for hypersonic flight.”

The flight successfully demonstrated stable aerodynamically controlled flight at speeds up to Mach 20 for nearly three minutes.

Sustaining hypersonic flight has been an extremely difficult task for aeronautical engineers over the years. While supersonic means that an object is traveling faster than the speed of sound, or Mach 1, “hypersonic” refers to an aircraft going five times that speed or more.

The Falcon hit Mach 20. At that speed, an aircraft could zoom from Los Angeles to New York in less than 12 minutes — 22 times faster than a commercial airliner. Take a look at what that looks like from the ground in the video below.

The August launch was the second flight of the Falcon technology. The first flight, which took place in April 2010, also ended prematurely with only nine minutes of flight time.

There aren’t any more flights scheduled for the Falcon program, which began in 2003 and cost taxpayers about $320 million.

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Researchers make alternatives to DNA and RNA – Los Angeles Times

DNA and RNA molecules are the basis for all life on Earth, but they don’t necessarily have to be the basis for all life everywhere, scientists have shown.

Researchers at the Medical Research Council in Cambridge, England, demonstrated that six synthetic molecules that are similar to — but not exactly like — DNA and RNA have the potential to exhibit “hallmarks of life” such as storing genetic information, passing it along and undergoing evolution. The man-made molecules are called “XNAs.”

“DNA and RNA aren’t the only answers,” said Vitor Pinheiro, the postdoctoral researcher who led the study, which was published this week in the journal Science.

Manipulating XNAs to behave like DNA and RNA could help scientists design better drugs, Pinheiro said.

It could also shed light on how life emerged on Earth, and on what living things might look like if they exist beyond our planet.

“Everyone wants to know what aliens would use for DNA,” said Steven Benner, a biochemist at the Foundation for Applied Molecular Evolution in Gainesville, Fla., who has synthesized artificial DNA but was not involved in the new study. “Lab experiments tell you about the possibilities in the universe.”

In natural life on Earth, the nucleic acids DNA and RNA are formed by sugar molecules — deoxyribose in DNA and ribose in RNA — that link to phosphates to form a backbone onto which the four nucleotide bases attach to form a chain.

Genetic information is stored in the order in which the bases — known by the chemical letters A, C, G and T — are strung along the chain.

DNA forms the template that holds all the information needed to create an organism. RNA takes that information and translates it into proteins, the basic building blocks of biology. (Viruses, which some scientists consider to be a life form, use only RNA.)

To build alternatives to DNA and RNA, scientists often fiddle with one component or another and see how the changes affect genetic function.

Pinheiro and his team worked with six molecules that use different sugars or sugar-like groups in place of deoxyribose and ribose. Something called CeNA, for instance, employs a ring-shaped structure called cyclohexene. Another variant called HNA used a group of atoms called anhydrohexitol.

Collectively, the scientists refer to the group as XNAs. The X stands for “xeno-,” the Greek prefix meaning “strange,” “foreign” or “alien.”

The researchers started with molecules that were already synthesized in other labs or sold by companies. The new part was demonstrating that the molecules were capable of passing along their genetic code. To do this, they had to engineer a group of enzymes that could read information stored in XNAs and write it onto DNA. After making make a bunch of copies of that DNA, they then used the enzymes to write those copies back to XNAs.

The group then showed that HNA was capable of evolution by making lots of copies of it, selecting out the ones with desired characteristics — in this case, the ability to bind to certain proteins — creating more copies of those, selecting out the best ones again, and so on.

“It’s domesticated breeding of molecules,” said Dr. Gerald Joyce, a researcher at the Scripps Research Institute in La Jolla, Calif., who was not involved in the study.

Joyce, who wrote an editorial for Science about the research, said the techniques Pinheiro and his colleagues used could some day make it easier for scientists to build nucleic acid-based medicines and diagnostic tests.

Today such products rely on RNA or DNA — both of which degrade quickly when exposed to enzymes called nucleases.

“If you take RNA and put it in a dish and breathe heavy, the RNA is a goner,” Joyce said.

With an XNA alternative, scientists could produce tests or therapies that are impervious to nucleases, potentially speeding the drug development process, Pinheiro said.

As for XNAs’ possible role in the evolution of life, Joyce said that scientists believe life on Earth probably was RNA-based before it became DNA-based — and could have been based on an even simpler XNA, such as TNA (made with a sugar called threose), before that.

“Some molecules developed the ability to replicate their own information, then we were off to the Darwinian races,” he said.

eryn.brown@latimes.com

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