Debunking myths on genetics and DNA

Tuesday, April 11, 2017

Looking for clues for past life on Mars

NASA's Curiosity Mars. Credits: NASA/JPL-Caltech/MSSS

On August 6, 2012, the NASA Curiosity rover landed on Mars at the base of Mount Sharp, a mountain the size of Kilimanjaro (~19,000 feet) in the middle of Gale Crater. Nina Lanza, space scientist at the Los Alamos National Laboratory, remembers the day well. As part of the team that built ChemCam, one of the ten instruments on the rover, she spent three months at the Jet Propulsion Laboratory in California, living on “Mars time” to follow Curiosity’s first “steps.”

ChemCam stands for “chemistry camera” and comprises a laser-induced breakdown spectroscopy (LIBS) instrument and a Remote Micro Imager (RMI). It was built at the Los Alamos National Laboratory in collaboration with the French space agency CNES. Nina Lanza and postdoctoral fellow Patrick Gasda are two of the Los Alamos scientists who work on the instrument.

“We get to shoot a laser on Mars for a living,” Lanza says, grinning.

And the laser on ChemCam is extremely powerful. When focused on a target, it vaporizes a small amount of material by heating Martian rocks to a temperature that’s roughly equivalent to that of the surface of the sun. “When we fire at a nearby target,” Gasda explains, “the elements get excited and, as they come down from that excited state, they emit light.”

By looking at the light emitted by the target, scientists can analyze the composition of rocks and soils on Mars. Previous Mars missions have found ice in the near-surface at high latitudes, begging the question: was there ever water on other parts of Mars at some point? And if there was—does that mean there could have been life, too?

With the very first laser shots from ChemCam, the answer was a definitive yes. “ChemCam discovered that all Martian dust is hydrated,” Lanza explains. “Given how dusty Mars is, this means that water is everywhere on the planet. We also found evidence that water was flowing in Mars’s past.”

“Gale Crater was filled with water,” Gasda adds. “From the sequence of sedimentary rocks we know of flowing streams in the crater that converged to a large body of still water that likely lasted for millions of years.”

“Curiosity gave us a picture of Gale Crater as an extremely habitable system,” Lanza continues. “We know that on Earth systems like this, with long-lasting neutral pH waters, would definitely support life.”

But how do you go about finding evidence for life? You search for clues, in other words, unique markers that identify biological activity.

“A potential marker could be manganese minerals,” Lanza says. In 2016 Curiosity found rocks rich in manganese-oxides at a location called Kimberley. “Manganese deposits in the terrestrial geological record mark the shift to higher concentrations of atmospheric oxygen due to the emergence of photosynthesis. This means that there could have been more oxygen in the Martian atmosphere in the past.”

Water. Oxygen. What about other building blocks of life? How do we look for those?

Nucleic and amino acids have been found in space,” Gasda tells me. “However, ribose—the ‘R’ in RNA, one of the first building blocks of life—and other sugars have never been found in space because they are too unstable. In order to have life, you need molecules that stabilize these sugars in water. Borates are particularly promising molecules for stabilizing sugars [1].”

Boron is highly soluble in water. In 2013 researchers from the University of Hawaii found boron in a meteorite from Mars [2]. That’s when Gasda became interested in this quest. “Once we knew that Gale Crater had once hosted a large body of water, it was natural to search for boron in those sediments.”

ChemCam did indeed find boron on Mars in 2016. Together with the manganese oxides, this is still not sufficient evidence for life on Mars, but it shows that some of the raw ingredients were present. The scientists are primed to keep looking. Curiosity has been on Mars almost five years (or 1660 sols), and its data is helping researchers fine-tune the instruments for the next Mars rover, provisionally named Mars 2020, to be launched in July 2020.

“We need to look for biosignatures,” Lanza says. “And we may not find them. But if we don’t, to me, the most striking question would be: what if there were indeed all the ingredients for life on Mars, yet life never happened? What made Earth so unique that life could happen here but nowhere else?”

Gasda nods. “And if we are indeed unique, shouldn’t this make us feel more special, and make us more cautious about the way we treat our planet and our biodiversity?”

I mention the current political climate, with the planned budget cuts to scientific research, and the appalling denial of any intervention to curb global warming.

“These cuts to basic research are disheartening,” Lanza says. “People often think of NASA research as esoteric and out of touch. And yet almost everyone has GPS technology on their smart phones today, something we owe to space research. Take the electron as another example. I’m sure people in the nineteenth century found J. J. Thomson’s research on the electron to be highly academic, with few practical applications. Yet without his discovery we wouldn’t have electricity, and our lives today would be fundamentally different.”

“The best measure for progress,” Lanza concludes, “is when you can’t imagine the knowledge you are going to gain. Let the science surprise you.”

Nina Lanza is a staff scientist, and Patrick Gasda is a postdoctoral research fellow, both in the Space and Remote Sensing group at the Los Alamos National Laboratory. They are both on the science team for the Curiosity Mars rover mission. The opinions expressed here are their own and not their employer’s. Both will be speaking at the March for Science in Santa Fe, New Mexico, on April 22nd.

[1] Ricardo, A. (2004). Borate Minerals Stabilize Ribose Science, 303 (5655), 196-196 DOI: 10.1126/science.1092464

[2] Stephenson, J., Hallis, L., Nagashima, K., & Freeland, S. (2013). Boron Enrichment in Martian Clay PLoS ONE, 8 (6) DOI: 10.1371/journal.pone.0064624

Monday, April 3, 2017

"Science is Under Attack." A Climate Scientist's Call to Action for the Future of our Planet.

Ocean currents and eddies in a high-resolution global ocean simulation. Image courtesy of MPAS-Ocean Team.

It’s a foggy morning in London. Meteorologist George Simpson, the director of the British Meteorological Office, sips his tea and opens a paper authored by a scientist named Guy Stewart Callendar. The last sentence of the abstract reads, “The temperature observations at 200 meteorological stations are used to show that world temperatures have actually increased at an average rate of 0.005°C per year during the past half century.”

Simpson shakes his head and thinks, “Nonsense. It’s all a coincidence.”

If this seems like a modern-day scene over climate change, you’ll be surprised to know that Callendar published his paper in 1938. And of course, his results, linking a global trend in temperature rises to atmospheric carbon dioxide concentrations, were received with a lot of skepticism. Almost 80 years later the debate is still ongoing.

“It is disheartening,” says Todd Ringler, climate scientist currently working at Los Alamos National Laboratory. “The reality is that there is no uncertainty about the basic premise of climate change. We know that CO2 concentrations are rising, we know why they are rising, and we know that CO2 tends to warm the atmosphere.”

In fact, this last effect — that CO2 warms the atmosphere — was shown by Irish physicist John Tyndall in 1859, over 150 years ago. But if the science on CO2 and its effect has been clear for so long, why does the public still have this preconception of uncertainty when it comes to global warming and climate change?

“There is essentially no doubt that temperatures are rising because of CO2 concentrations,” Ringler explains. “The biggest uncertainty controlling global temperature in year 2100 is what our energy future will look like. In other words, we cannot estimate how much the temperatures will rise until we decide how dependent we want to be on fossil fuels going forward.”

“Basically what you’re saying,” I interject, “is that the largest uncertainty here is human behavior, because we still haven’t made up our mind on what, if anything, we want to do about global warming.”

“Exactly. I recently republished an op-ed I wrote ten years ago on the science and politics of global climate change,” Ringler says. “Unfortunately, 10 years later, the debate hasn’t changed, but all this litigation on the basic science is futile. The science is established, now we need to discuss policies.”

In his op-ed, Ringler has some stern words for our leaders: “Our government was failing us 10 years ago, and it's still failing us today by moving steadily away from a position of international leadership for crafting a comprehensive policy framework.”

“Why do you believe we still can’t come up with an agreement on this?” I ask.

Ringler sighs. “Humans have a long history of learning by experience, by trial and error. Take vaccines, for example. When we stop vaccinating, pockets of outbreaks resurface to remind us why we invented vaccines in the first place. Climate change happens over such a long time scale and carbon stays in the atmosphere for such a long time that we don’t have the luxury of learning by trial and error here. We have to get this right the first time, and we are not good at that. Day-to-day the biggest challenge we are facing when it comes to climate change is that we cannot pin down any single event to global warming. Weather is by its own nature random, but what global warming is doing is making certain random outcomes more likely than others. It’s shifting the roll of a dice, so to speak.”

And taken all together, these “random” events scattered across the globe are indeed making an impact: the ice caps have been steadily shrinking for the past 38 years of satellite records; the increasing amounts of CO2 retained by sea water are causing ocean acidification, harming marine organisms; weather patterns are becoming more severe, with stronger floods and longer droughts.

“What do you see as the biggest challenge posed by the current administration?”

“The current administration is ideologically opposed to regulations. But we need some rules, whatever they look like, to limit the amount of carbon in the atmosphere. Look, renewable energy is happening. Take Texas, for example, which is pioneering wind energy. Las Vegas is now mostly powered by clean energy. The very same oil companies we often think of as opposing regulations on carbon missions are actually advocating for us to take action. But the problem is global and as such it requires global agreements and global solutions. It does matter what country emits the carbon, the carbon harms everyone. All nations need to come together and share the opportunities and costs of transitioning away from fossil fuels. What the current administration needs to understand is that what they see as ‘regulations’ are in fact ‘protections’ that we need to put forward to safeguard our future and our children’s future.”

“What pains me the most,” Ringler continues, “is the disconnect between science and policy. We have this disconnect between knowing something and acting accordingly. Knowledge has lost its primary role in our society, and now science is under attack. This is not healthy. A healthy society is one in which the knowledge we gather through science informs the policy making.”

As Ringler wrote in his op-ed, “We owe it to ourselves and to future generations to ask the following question: What if our present understanding of global climate change is correct? What does this mean for our society? What will happen to water in the already arid West? What will happen to agriculture, both here and around the world? Can developing nations accommodate these changes? And if not, how will we deal with the climate-driven conflict that will surely follow?”

Dr. Todd Ringler has 25 years of experience modeling the climate of the atmosphere and ocean. He studied at Cornell and Princeton University, then joined the research faculty at Colorado State University and is presently a scientist working at Los Alamos National Laboratory. He is member of the International CLIVAR Ocean Model Development Panel and a long-time advocate for sensible solutions to address climate change impacts. The views and opinions expressed here are Todd Ringler’s own thoughts on this subject. He will be speaking at the March for Science in Santa Fe, New Mexico on April 22nd.


[1] Callendar, G. (1938). The artificial production of carbon dioxide and its influence on temperature Quarterly Journal of the Royal Meteorological Society, 64 (275), 223-240 DOI: 10.1002/qj.49706427503