New Signs of Long-Gone Life on Mars

A spectacular nail-biter of a landing was just the beginning. This was the year Mars’ rover Curiosity proved its worth by giving researchers unprecedented access to the Red Planet.



Curiosity looks back at the walls of Gale Crater in this colorized view.

In 1976, the Viking spacecraft gave us the first clear picture of the Martian surface — and sparked hopes that the barren, toxic planet once hosted life. In 2013, the rover Curiosity found the most convincing evidence yet that the planet was once habitable, as well as clues about why life there might have died out.

The $2.5 billion rover, roughly the size of a Mini Cooper automobile, discovered an ancient streambed soon after landing — evidence that water once flowed there. Next, Curiosity used its considerable payload of geologic tools to dig up further proof. 

Its robotic arm drilled a 2.5-inch borehole in mudstone bedrock. The robot fed the resulting rock powder into its Sample Analysis at Mars (SAM) instrument, which heated the sample, vaporizing it into gases that the tool could analyze.

Meanwhile, the Chemistry and Mineralogy (CheMin) tool beamed X-rays at the powder. The scattering of the rays reveals crystal structures, making it possible to identify Martian minerals.

The findings: carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorous — key ingredients for life — plus chemicals such as sulfur dioxide and hydrogen sulfide that could provide energy for microorganisms. All were found in a locale that was once wet, and neither too salty nor too acidic.

“To tie that all up in one ball of twine: We found a habitable environment,” says John Grotzinger, Mars Science Laboratory project scientist at the California Institute of Technology.

Nonetheless, the rover found no sign of methane in the atmosphere, dashing hopes that methane-producing microbes might still dwell there now. By sampling other atmospheric gases, Curiosity also found one reason why life-friendly conditions vanished. 

Compared to the raw materials found elsewhere in the solar system (a record preserved in the sun and the gaseous planets Jupiter, Saturn, Uranus and Neptune) the Martian atmosphere has more heavy isotopes — heavier versions of basic elements such as carbon and oxygen. The skewed ratio suggests that the planet’s lighter isotopes escaped as part of a gaseous atmosphere and left a disproportionate amount of the heavy ones behind. 

The rover’s journey also collected evidence that a manned mission to Mars would require better shielding to safeguard the crew. The spacecraft carrying Curiosity found that with today’s propulsion and shielding technology, Mars-bound astronauts would be exposed every five or six days to as much radiation as a whole-body CT scan, a total of about 662 millisieverts by the end of the yearlong round-trip journey. This figure is beyond safety guidelines and enough to raise lifetime cancer risk by as much as 3 percent.

NASA is testing out new lightweight, durable shielding materials such as one made with hydrogen-filled nanotubes. Unlike larger atoms, when hydrogen is hit by cosmic rays it does not break down into showers of secondary particles that bombard astronauts with additional radiation.

Curiosity is now trekking toward the 3.4-mile-high Mount Sharp, where exposed rock layers that have preserved billions of years of geologic history may reveal more secrets about the Red Planet’s past. The rover should cover the five rugged miles in about a year. “Right now, it’s pedal to the metal,” says Grotzinger.

Russian Forces Double Along Ukraine Border

American officials are worried that 50,000 Russian troops being massed near the Ukraine border and within Crimea, the pro-Russian peninsula recently annexed by President Vladimir Putin, aren't there for just a training exercise

Despite Russian reassurances that Moscow’s troop buildup along Ukraine’s eastern frontier is for a military exercise, its growing scale is making U.S. officials nervous about its ultimate aim.

President Barack Obama on Friday urged Russia to stop “intimidating” Ukraine and to pull its troops back to “de-escalate the situation.” He told CBS that the troop buildup may “be an effort to intimidate Ukraine, or it may be that [Russia has] additional plans.”

Pentagon officials say they believe there could be close to 50,000 Russian troops bordering the former Soviet republic and inside Crimea, recently seized and annexed by Moscow. That estimate is double earlier assessments, and means Russian President Vladimir Putin could order a lighting strike into Ukrainian territory with the forces already in place. The higher troop count was first reported by the Wall Street Journal.

“We continue to see the Russian military reinforce units on their side of the border with Ukraine to the south and to the east of Ukraine,” Rear Admiral John Kirby, the Pentagon spokesman, said Thursday. “They continue to reinforce and it continues to be unclear exactly what the intent there is.”

State Department spokeswoman Marie Harf played down the notion that there are as many as 100,000 Russian troops now bordering Ukraine, as Olexander Motsyk, the Ukrainian ambassador to the U.S., said Thursday on Capitol Hill. “I hadn’t actually seen the hundred-thousand number,” Harf said. “There are huge numbers of Russian troops on the Ukrainian border. … We are concerned about Russia taking further escalatory steps with whatever number of tens of thousands of troops they have there, and have called on them not to do so.”

Washington got those assurances that the Russian troop buildup was only an exercise from Russian Defense Minister Sergei Shoigu a week ago. But no one in the U.S. government knows if Putin agrees—or if the Russian leader has changed his mind as the West has debated what level of economic and political sanctions might be imposed if Moscow takes an additional chunk of Ukraine beyond Crimea. “They made it clear that their intent was to do exercises and not to cross the border,” Kirby said. “Our expectation is they’re going to live up to that word.”

There is no plan to involve the U.S. military in what is happening in Ukraine, even if Russia takes more territory. Ukraine borders Russia, and Ukraine does not belong to NATO, where an attack on one member is deemed to be an attack on all.

“Should the Russians continue to move aggressively in that region and in the Ukraine, what does that mean—and NATO would have to respond, for example—what would that mean for the United States Army?” Rep. Tim Ryan, D-Ohio, asked the Army’s top officer Thursday.

“My responsibility is to make sure that the U.S. Army is prepared to respond as part of a joint force, as part of NATO,” General Ray Odierno, the Army chief of staff, responded. “So what I’m focused on is improving our readiness in combat, combat service support and combat aviation capabilities to make sure we’re ready to respond whether it’s from a humanitarian assistance aspect or any other aspect.”

How many of the 67,000 U.S. troops in Europe might be involved? “I simply don’t know,” Odierno said. “And I would just remind people that, actually, some of the soldiers that are assigned to Europe actually right now are in Afghanistan.”

Lawmakers suggested that the world is abandoning Ukraine. “It appears to me Ukraine was left defenseless over the last two decades,” said Rep. Marcy Kaptur, D-Ohio.

“Ukraine has stood with us both in Iraq and Afghanistan,” added Rep. Rodney Frelinghuysen, R-N.J. “We’re highly appreciative and recognize their sacrifice.”

The U.S. has made plain it is not rushing military aid of any kind to Ukraine, despite Kiev’s requests. Ukraine has sought lethal military aid—small arms and ammunition—but that is off the table. “The rations, the Meals Ready to Eat, they are on the way,” Kirby said. “We expect them to arrive in Ukraine probably by the weekend is the best estimate. They’re going over land.”

Obama stressed Thursday that economic and political sanctions would be the primary weapons the international community would be brandishing to curb Russian aggression against Ukraine. “I’ve been very clear in saying that we are going to do everything we can to support Ukraine and the Ukrainian people,” he said in Rome. “But I think that it’s also important for us not to promise and then not be able to deliver.”