WASHINGTON — There’s a long-standing joke that NASA is always 20 years from putting astronauts on Mars. Mission details shared at a recent summit shows that the space agency is right on schedule. A to-do list from 2015 looks remarkably similar to one compiled in 1990. One difference: NASA is now building a rocket and test-driving technologies needed to get a crew to Mars. But the specifics for the longest road trip in history — and what astronauts will do once they arrive — remain an open question.

“Are we going to just send them there to explore and do things that we could do robotically though slower, or can we raise the bar?” asked planetary scientist Jim Bell during the Humans to Mars summit. “We need to make sure that what these folks are being asked to do is worthy of the risk to their lives,” said Bell, of Arizona State University in Tempe.
The three-day symposium, which ended May 19, was organized by Explore Mars Inc., a nonprofit dedicated to putting astronauts on Mars by the 2030s.

While the summit didn’t break new scientific ground, it did bring together planetary scientists , space enthusiasts and representatives from both NASA and the aerospace industry to talk about the challenges facing a crewed mission to Mars and rough ideas for how to get there.

Part of the appeal in sending humans is the pace of discovery. Drilling just one hole with the Curiosity rover, which has been exploring Gale Crater on Mars since August 2012 (SN: 5/2/2015, p. 24), currently takes about a week. “It’s a laborious, frustrating, wonderful — frustrating — multiday process,” said Bell.

Humans also can react to novel situations, make quick decisions and see things in a way robotic eyes cannot. “A robot explorer is nowhere near as good as what a human geologist can do,” says Ramses Ramirez, a planetary scientist at Cornell University. “There’s just a lot more freedom.”

Researchers saw the human advantage firsthand in 1997 when they sent a rover called Nomad on a 45-day trek across the Atacama Desert in Chile. Nomad was controlled by operators in the United States to simulate operating a robot on another planet. Humans at the rover site provided a reality check on the data Nomad sent back. “There was a qualitative difference,” says Edwin Kite, a planetary scientist at the University of Chicago. And it wasn’t just that the geologists could do things faster. “The robots were driving past evidence of life that humans were finding very obvious.”
To get astronauts ready to explore Mars, the Apollo program is a good template, said Jim Head, a geologist at Brown University who helped train the Apollo astronauts. “Our strategy was called t-cubed: train them, trust them and turn them loose.” While each of the moon expeditions had a plan, the astronauts were trusted to use their judgment. Apollo 15 astronaut David Scott, for example, came across a chunk of deep lunar crust that researchers hoped to find although it wasn’t at a planned stop. “He spotted it three meters away,” said Head. “He saw it shining and recognized it immediately. That’s exploration.”

Despite a lack of clear goals for a jaunt to Mars, NASA is forging ahead. The Orion crew capsule has already been to space once; a 2014 launch atop a Delta IV Heavy rocket sent an uncrewed Orion 5,800 kilometers into space before it splashed down in the Pacific Ocean (SN Online: 12/5/2014). And construction of the Space Launch System, a rocket intended to hurl humans at the moon and Mars, is under way. The first test flight, scheduled for October 2018, will send Orion on a multiday uncrewed trip around the moon. NASA hopes to put astronauts onboard for a lunar orbit in 2021.

Meanwhile, the crew aboard the International Space Station is testing technologies that will keep humans healthy and happy during an interplanetary cruise. Astronaut Scott Kelly recently completed a nearly yearlong visit to the station intended to reveal the effects of long-duration space travel on the human body (SN Online: 2/29/2016). And on April 10, a prototype inflatable habitat — the Bigelow Expandable Activity Module — arrived at the station and was attached to a docking port six days later. The station crew will inflate the module for the first time on May 26. No one will live in it, but over the next two years, astronauts will collect data on how well the habitat handles radiation, temperature extremes and run-ins with space debris.
Beyond that, the plans get fuzzy. The general idea is to construct an outpost in orbit around the moon as a testing and staging ground starting in the late 2020s. The first crew to Mars might land on the planet — or might not. One idea is to set up camp in Mars orbit; from there, astronauts could operate robots on the surface without long communication delays. Another idea has humans touching down on one of Mars’ two moons, Phobos or Deimos. When crews do land on the Martian surface, NASA envisions establishing a base from which astronauts could plan expeditions.

With so few details, it’s difficult for the space agency to identify specific technologies to invest in. “There have been lots of studies — we get a lot of grief that it’s nothing but studies,” said Bret Drake, an engineer at the Aerospace Corp. in El Segundo, Calif. “But out of the studies, there are a lot of common things that come to the top no matter what path you take.”

Any mission to Mars has to support astronauts for roughly 500 to 1,000 days. The mission has to deal with round-trip communication delays of up to 42 minutes. It will need the ability to land roughly 40-ton payloads on the surface of Mars (current robotic missions drop about a ton). Living off the land is also key, making use of local water and minerals. And astronauts need the ability to not just survive, but drive around and explore. “We want to land in a safe place, which is going to be geologically boring, but we want to go to exciting locations,” said Drake.

The technical and logistical challenges might be the easiest part. “We do know enough to pull this off,” Ramirez says. “The biggest problem is political will.” Congress has yet to sign off on funding this adventure (nor has NASA presented a budget — expected to be in the hundreds of billions of dollars), and future administrations could decide to kill it.

Multiple summit speakers stressed the importance of using technology that is proven or under development — no exotic engines or rotating artificial gravity habitats for now. And a series of small missions —baby steps to the moon and an asteroid before committing to Mars — could show progress that might help keep momentum (and public interest) alive.

“We thought going to the moon was impossible, but we got there,” says Ramirez. “If we dedicate ourselves as a nation to do something crazy, we’ll do it. I have no doubt.”

Schrödinger’s cat can’t seem to catch a break. The unfortunate imaginary feline is famous for being alive and dead at the same time, as long as it remains hidden inside a box. Scientists have now gone one step further, splitting one living-dead cat between two boxes.

Animal lovers can relax — there are no actual cats involved. Instead, physicists used microwaves to mimic the cat’s weird quantum behavior. The new advance, reported May 26 in Science, brings scientists a step closer to building quantum computers out of such systems.
Schrödinger’s cat is the hapless participant in a hypothetical experiment dreamt up by physicist Erwin Schrödinger in 1935. He imagined a cat in a closed box with a lethal poison that will be released if a sample of radioactive material decays. After any given amount of time passes, quantum math can provide only the odds that the material has decayed and released the poison. So from the quantum perspective, the cat is in a state of superposition — both dead and alive. It remains in limbo until the box is opened, and out comes a purring kitty or a lifeless corpse (SN: 11/20/10, p. 15).

In a real laboratory version of the experiment, microwaves inside a superconducting aluminum cavity take the place of the cat. Inside the specially designed cavity, the microwaves’ electric fields can be pointing in two opposing directions at the same time — just as Schrödinger’s cat can be simultaneously alive and dead. These states are known as “cat states.” Now, physicists have created such cat states in two linked cavities, thereby splitting the cat into two “boxes” at once.

Though the idea of one cat in two boxes is “kind of whimsical,” says Chen Wang of Yale University, a coauthor of the paper, it’s not that far off from the real-world situation. The cat state “is shared in two boxes because it’s a global quantum state.” In other words, the cat is not only in one box or the other, but stretches out to occupy both.

Because the states of the two boxes are linked — or in quantum parlance, entangled — if the cat turns out to be alive in one box, it’s also alive in the other (SN: 11/20/10, p. 22). Wang compares it to a cat with two symptoms of life: an open eye in the first box and a heartbeat in the second box. Measurements from the two boxes will always agree on the cat’s status. For microwaves, this means the electric field will always be in sync in both cavities. The scientists measured the cat states produced and found a fidelity of 81 percent — a measure of how close the state was to the ideal cat state. This fidelity is comparable to that achieved in similarly complex systems, the researchers say.

The result is a step toward quantum computing with such devices. The two cavities could serve the purpose of two quantum bits, or qubits. One stumbling block for quantum computers is that errors inevitably slip in to calculations due to interactions with the outside environment that muck up the qubits’ quantum properties. The cat states are more resistant to errors than other types of qubits, the researchers say, so the system could eventually lead to more fault-tolerant quantum computers.
“I think they’ve made some really great advances,” says Gerhard Kirchmair of the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences in Innsbruck. “They’ve come up with a very nice architecture to realize quantum computation.”

The demonstration of entanglement in the two-cavity system is very important, says Sergey Polyakov of the National Institute of Standards and Technology in Gaithersburg, Md. “The next step would be to demonstrate that this approach is actually scalable” by adding more cavities to the mix to build a bigger quantum computer.

Peppered moths and copycat butterflies owe their wing color-changing abilities to a single gene, two independent studies suggest.

A genetic tweak in a portion of the cortex gene that doesn’t make protein painted the speckled gray wings of peppered moths black, researchers report online June 1 in Nature. Genetic variants in DNA interspersed with and surrounding the cortex gene also help some tasty species of Heliconius butterflies mimic unpalatable species and avoid getting eaten by predators, a second team of scientists reports, also June 1 in Nature.
In the often-told evolutionary tale, the color shift in moths began as factories in Britain started to darken the skies with coal smoke during the Industrial Revolution in the 1800s. Victorian naturalists took note as a newly discovered, all-black carbonaria form of peppered moths (Biston betularia) blended into soot-covered backgrounds; the light-colored typica moths, which lacked the mutation, were easily picked off by birds. By 1970, nearly 99 percent of peppered moths were black in some localities. As air pollution decreased in the late 20th century, black moths became more visible to birds. As a result, carbonaria moths are now rare.

“This begins to unravel exactly what the original mutation was that produced the black … moths that were favored by natural selection” during much of the last century, says evolutionary biologist Paul Brakefield of the University of Cambridge in England. “It adds a new and exciting element to the story.”

Wing pattern changes in butterflies and peppered moths are textbook examples of natural selection, but the molecular details behind the adaptation have eluded scientists for decades. In 2011, researchers tracked the traits to a region of a chromosome all the species have in common (SN: 5/7/11, p. 11; SN: 9/24/11, p. 16). Which of the many genes in that region might be responsible remained a mystery.
In peppered moths, the region of interest stretches over about 400,000 DNA bases and contains 13 genes and two microRNAs. “There aren’t really any genes that scream out to you, ‘I’m involved in wing patterning,’” says evolutionary geneticist Ilik Saccheri at the University of Liverpool in England.
Saccheri and colleagues compared that region in one black moth and three typical moths. The researchers found 87 places where the black moth differed from the light-colored moths. Most of the differences were changes in single DNA bases — the information-carrying chemicals in DNA. Such genetic variants are known as SNPs for single nucleotide polymorphisms. One difference was the insertion of a 21,925-base-long stretch of DNA into the region. This big chunk of DNA contained multiple copies of a transposable element, or jumping gene. Transposable elements are viruslike pieces of DNA that copy and insert themselves into a host’s DNA.

By examining the DNA of hundreds more typica moths and ruling out mutations one by one, the team ended up with one candidate: the large transposable element that had landed in the cortex gene. But the jumping gene didn’t land in the DNA that encodes the protein. Instead it landed in an intron — a stretch of DNA that gets chopped out after the gene is copied into RNA and before a protein is made.

The jumping gene first landed in the cortex intron in about 1819, the researchers calculated from historical measurements of how common the trait was throughout history. That timing gave the mutation about 20 to 30 moth generations to spread through the population before people first reported sightings of the black moths in 1848. Saccheri and colleagues found the transposable element in 105 of 110 wild-caught carbonaria moths and none of the 283 typica moths tested. The remaining five moths are black because of another, unknown, genetic variation.

Similarly, Nicola Nadeau, an evolutionary geneticist at the University of Sheffield in England, and colleagues combed through more than 1 million DNA bases in each of five species of Heliconius butterflies. The researchers were looking for genetic variants associated with the presence or absence of yellow bands on the wings.

Nadeau’s team found 108 SNPs in all H. erato favorinus butterflies that have a yellow band on their hind wings. Most of those SNPs were in introns of the cortex gene or outside of the gene. Butterflies that lack the yellow band don’t have those SNPs.

Other DNA changes were found to draw yellow bars on the wings of different species of Heliconius butterflies, suggesting that evolution acted multiple times on the cortex gene with similar results.

The finding that the same gene influences wing patterns in butterflies and moths supports an idea that some genes are hot spots of natural selection, says Robert Reed, an evolutionary biologist at Cornell University.

None of the genetic differences in the butterflies or peppered moths change the cortex gene itself. That leaves open the possibility that the transposable element and SNPs aren’t doing anything to cortex, but may be regulating a different gene. But the evidence that cortex really is the gene upon which natural selection has acted is strong, says Reed. “I’d be surprised if they were wrong.”

Still, it’s not obvious how cortex changes wing patterns, says Saccheri. “We’re both equally puzzled about how it is doing what it appears to be doing.” The teams have evidence that cortex helps determine when certain wing scales grow. In butterflies and moths, the timing of wing scale development affects the color of the wings, says Reed. “You see colors popping up almost like a paint-by-numbers.”

Yellow, white and red scales develop first. Black scales come later. Cortex is known to be involved in cell growth. So varying levels of the protein may speed up development of wing scales, causing them to become colored, or slow their growth, allowing them to turn black, the researchers speculate.

A sloppy light system may be just what a squid needs to hide from predators. Bioluminescent cells in some glass squid work in a surprisingly inefficient way — leaking a lot of light rather than fully channeling it, a new study suggests.

Glass squid have largely transparent bodies, helpful for inconspicuous swimming in deep open water. Marine predators often scan the waters above them for the telltale silhouettes of prey blocking sunlight, but there’s little to betray a glass squid — except for a few notable features such as the shadow-making eyes on its head.
Underneath those eyes, squid in the genus Galiteuthis grow silvery patches of cells that act as undersurface bioluminescence, a camouflage technique that has evolved in various marine creatures, making their shadows less conspicuous to hunters below.

Biophysicist Alison Sweeney of the University of Pennsylvania in Philadelphia had hypothesized that the cells, called photophores, act like microscopic cables that channel the bioluminescent glow of the squid down or out in a specific direction. The skinny, cablelike cells are surrounded by thin, protein-dense layers that create a silver tube that reminds Sweeney of Saran Wrap. But in the first detailed look at these structures, Sweeney and Pennsylvania colleague Amanda Holt found that the channels performed poorly, letting most of the light leak away sideways. That efficiency, it turns out, could be useful, Sweeney and Holt report June 8 in the Journal of the Royal Society Interface.
“We always expect that the most ‘perfect’ or efficient mechanism will be the pinnacle of evolution, but this study shows that there are many ways to solve challenges imposed by the environment,” says marine biologist Steven Haddock of Monterey Bay Aquarium Research Institute in California.

Inefficiency might sound like an improbable scenario for success. But, says visual ecologist Justin Marshall of the University of Queensland in Brisbane, Australia, “I believe it.”

Other researchers had discussed the idea that certain sea creatures show a great deal of subtlety in disguising their silhouettes, but Sweeney knew of no other study trying to figure out how supposed cables work.
It turns out that the squid structures were “really bad at being fiber-optic cables,” Sweeney says. The cells are about 50 micrometers long, longish for a cell but short for a cable. And the cells couldn’t guide light even over that short distance without losing much of it. Looking at the cross sections of the photophores under a microscope showed big, uneven gaps in the layers. When she first recognized this, she expected to write “a boring paper that’s, ‘Gee, squid cells kind of sort of guide light, but not really.’”

Then came the “of course” moment for Sweeney and her puzzling measurements. “The lesson that keeps coming back to us,” she says, “is that these things are meaningless until you consider the habitat.” After calculating the light environment where wild squid swim, the researchers realized that the overall effect of the leaking tubes created a plausible approximation for the twilightlike haze in which the squid live. A glowing blur might actually make the eyes less conspicuous to predator approaching from a variety of angles.

Irregularities in the sheathing and shapes of the leaky cables might even make the living cables more remarkable, Sweeney speculates. Dividing them into five rough types, the researchers investigated the kinds of light effects each produced and matched those effects with ocean conditions at two locations off Hawaii. If squid can pick which cable doodads to use and when, the animals could improve the match between their under-eye shine and conditions in the ocean.

Other squid with opaque skin flicker, darken and quick-change their tiny color-making structures, she points out. So, the suggestion that eye-glow structures might change, too, “is not crazy,” Sweeney says.