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Joel Hurowitz

Joel Hurowitz

By Daniel Dunaief

February 18th marked an end and a beginning.

On that day, the Mars Perseverance rover descended through the atmosphere with considerable fanfare back on Earth. Using some of the 23 cameras on Perseverance, engineers took pictures and videos of the landing.

The National Aeronautics and Space Administration not only shared the video of the rover descending into the Jezero crater which held water and, perhaps, life three billion years ago, but also offered a view of the elated engineers who had spent years planning this mission.

 

In a calm, but excited voice, a female narrator counted down the height and speed of the rover, which weighs about a ton on Earth and closer to 800 pounds in the lower gravity of Mars. The NASA video showed staff jumping out of their seats, cheering for the achievement.

Launched from Cape Canaveral, the rover took 233 days to reach Mars, which is about the gestation period for a chimpanzee.

Some of the engineers “who got us there have reached the end of their marathon,” said Joel Hurowitz, Associate Professor in the Department of Geosciences at Stony Brook University and Deputy Principal Investigator for one of the seven scientific instruments aboard the Perseverance. 

With ongoing support from other engineers who helped design and build the rover, the scientists “get the keys to the vehicle and we get to start using these things.”

Indeed, Hurowitz and Scott McLennan, Distinguished Professor in the Department of Geosciences at Stony Brook University are part of teams of scientists who will gather information to answer basic questions about Mars, from whether life existed, to searching for evidence of ancient habitable environments, to seeking evidence about the changing environment.

Both Stony Brook scientists were riveted by the recordings of the landing.

Scott McLennan

Hurowitz marveled at the cloud of dust that formed as the rover approached the surface.“You could see these chunks of rock flying back up at the sky crane cameras,” he said. “I was amazed at the amount of debris that was kicked up in the landing process.”

Hurowitz had seen pieces of rock on top of the Curiosity rover after it landed, but he felt he understood more about the process from the new video. “To see it happening, I realized how violent that final stage of the landing is,” he said.

McLennan said this has been his sixth Mars mission and he “never tires of it. It’s always exciting, especially when there is a landing involved.”

Like Hurowitz, who earned his PhD in McLennan’s lab at Stony Brook, McLennan was impressed by the dust cloud. “I understood that a lot of dust and surface debris was displaced, but it was quite remarkable to see the rover disappear into the dust for a short while,” he wrote in an email.

While previous missions and orbiting satellites have provided plenty of information about Mars, the Perseverance has the potential to beam pictures and detailed analysis of the elements inside rocks.

Hurowitz, who helped build the Planetary Instrument for X-ray Lithochemistry, or PIXL, said the team, led by Abigail Allwood at the Jet Propulsion Laboratory, has conducted its first successful instrument check, which involves turning everything on and making sure it works. Around April, the PIXL team will start collecting its first scientific data.

In addition to searching for evidence of previous life on Mars, Hurowitz will test a model for climate variation.

The SuperCam on the Perseverance Rover. Photo by Gregory M. Waigand

From measurements of the chemistry and mineralogy of sedimentary rock, the scientists can deduce whether the rocks formed in an environment that was oxygen-rich or oxygen-poor. Additionally, they can make inferences about temperature conditions based on their chemical compositions.

Looking at variations in each layer, they can see whether Mars cycled back and forth between cold and warm climates.

Warmer periods could have lasted for hundreds, thousands or even tens of thousands of years, depending on how much greenhouse gas was injected at any time, Hurowitz explained. “Whether this is long enough to enable biological development is probably one of the great questions in the field of pre-biotic chemistry,” he said.

The Martian atmosphere could have had dramatic swings between warm and oxygen-poor conditions and cold and oxygen-rich conditions. “This has not really been predicted before and provides a hypothesis we can test with the rover payload for how climate might have varied on Mars,” he added.

Tempering the expectation of confirming the existence of life, Hurowitz said he would be “shocked if we woke one morning and a picture in the rover image downlink [included] a fossil,” he said. “It’s going to take time for us to build up our understanding of the geology of the site well enough.” The process could take months or even years.

Using information from orbiters, scientists have seen minerals in the Jezero crater that are only found when water and rock interact.

With the 11-minute time lag between when a signal from Earth reaches Perseverance, Hurowitz said scientific teams send daily codes up to the rover and its instrument. Hurowitz will be involved in uploading the signals for PIXL.

A Martian day is 40 minutes longer than the Earth day, which is why the Matt Damon movie “The Martian” used the word “sol,” which represents the time between sunrises on Mars.

McLennan, who works on three teams, said PIXL and the SuperCam provide complementary skill sets. With its laser, the SuperCam can measure the chemical composition of rocks at under seven meters away. Up close, PIXL can measure sub millimeter spot sizes for chemistry.

SuperCam will then find areas of interest, enabling PIXL to focus on a postage-stamp sized area.

As a member of the Returned Sample Science Working Group, McLennan, who is a specialist in studying the chemical composition of sedimentary rocks, helps choose which rocks to collect and set aside to bring back to Earth. The rocks could return on a mission some time in the 2030s.

The scientists will collect up to 43 samples, including some that are completely empty. The empty tubes will monitor the history of contamination that the other rock samples experienced. 

For McLennan, the involvement of his former student is especially rewarding. Hurowitz “didn’t just help build the instrument, he’s one of the leaders,” McLennan said. “That’s really fabulous.”

For Hurowitz, any data that supports or refutes the idea about the potential presence of life on Mars is encouraging.

He is “cautiously optimistic” about finding evidence of past life on Mars. “We’ve done everything we can as a scientific community to maximize the chance that we’ve landed some place that might preserve signs of life.”

Joel Hurowitz before the PIXL launch at the end of July. Photo by Tanya Hurowitz

By Daniel Dunaief

For six years, Joel Hurowitz worked as Deputy Principal Investigator on a team to build an instrument they would send to another planet.

Joel Hurowitz

An Assistant Professor of Geosciences at Stony Brook University, Hurowitz and the team led by Abigail Allwood at the NASA Jet Propulsion Laboratory created an instrument that would search for evidence of life that is likely long ago extinct on Mars.

The team designed a 10-pound machine (which will weigh less than four pounds in Mars’s lower gravity environment) that is about the size of a square lunchbox and houses x-ray equipment that can search along the surface of rocks for life that may have existed as long as three to four billion years ago.

Mars’s surface environment became less hospitable to life starting around three billion years ago, when the planet lost most of its atmosphere, causing the surface to dry out and become extremely cold. Surface life at this point likely became extinct.

Called the Planetary Instrument for X-ray Lithochemistry, or PIXL, the instrument was one of seven that lifted off at the end of July as part of a Mars 2020 mission. The Perseverance rover will land at the Jezero Crater on the Red Planet on February 18th, 2021.

After all that work, Hurowitz had planned to watch the launch with his family in Florida, but the pandemic derailed that plan.

“I got to watch the launch with my family,” Hurowitz said. He was on two zoom conferences, one with the Mars 2020 team and the other with members of the Department of Geosciences at Stony Brook. “It was a really special experience” and was the “best teleconference of the last six months,” he said.

As the rocket makes its 35.8 million mile journey to Mars, the JPL team will turn on the PIXL to monitor it, run health checks and do routine heating of the components to make sure it is operating. After the rocket lands, the rover will go through a commissioning period. Numerous subsystems need to be checked out, explained Hurowitz.

The first test for the PIXL will be to analyze a calibration target the researchers sent to Mars, to make sure the measurements coincide with the same data they collected numerous times on Earth. This ensures that the instrument is “working the way we want it to. That’ll happen in the first 40 sols.”

A sol is a day on Mars, which is slightly longer by about 40 minutes than a day on Earth.

Once it passes its calibration test, the PIXL can start collecting data. Hurowitz described the instrument as “incredibly autonomous.” It sits at the end of the rover’s arm. When the scientists find a rock they want to explore, the PIXL moves an inch away from the surface of the rock and opens its dust cover. The scientists take pictures with a camera and a set of laser beams. These beams help determine whether the PIXL is an optimal distance from the rock. If it isn’t, the instrument manipulates itself, using struts that allow it to extend or retract away from the rock.

Once PIXL gets in the right position, it fires an X-ray beam into the rock. The beam is about the diameter of a human hair. The x-ray that hits the rock is like wind going through chimes. Rather than make a familiar sound, the elements in the rock emit a specific x-ray signal as the atoms return to their ground state. Putting together the signals from the rock enables Hurowitz and the PIXL crew to determine its chemistry.

Even though the rocks are likely a combination of numerous elements, they “separate themselves cleanly in our spectra,” Hurowitz said. The SBU Geosciences expert expects the elements in the rocks to have different proportions than on Earth. Mars, for example, has more iron than sodium. A granite rock on Earth would likely have considerable sodium and some potassium, with a little iron.

Hurowitz and the PIXL team will be looking for rocks that may have evidence of prokaryotic organisms that are Mars’s versions of similar species found in undisturbed areas of Western Australia, where researchers discovered ancient fossilized life.

The rocks in Australia contain the oldest accepted fossilized forms of life, which are about 3.5 billion years old and are considered the best analogues for what the PIXL team might find on Mars.

In Australia, which is where Allwood grew up, scientists discovered microbial mats, which are single-celled organisms that build up, one layer after another, into a colony. These mats worked together to build up towards the sunlight, which fuels their metabolism. They use raw chemicals in the environment like dissolved sulfur, iron and manganese.

The Martian mats, if they find them, likely had to adapt to considerably different conditions than on Earth. The Martian environment may not have had large oceans or river systems and craters filled with lakes.

The scientists won’t be able to look for an individual microbe, but rather for indirect signals, such as laminated structures that formed in ways that are unique to microbial communities.

Hurowitz, Allwood and the PIXL team are looking for clues from an unusual lamination in the rock that they would likely associate with a microbial mat. By looking closely at the lamination, they may be able to develop hypotheses about whether a mat was taking chemicals out and depositing it to make a mineralized home for itself.

If they find rocks of interest, the rover’s drill will collect a sample and hermetically seal it in a tube.

A future mission to Mars, planned for 2026, could retrieve some of these samples, which, when they return, could confirm the presence of life on Mars. PIXL will continue to operate as long as the filament in the x-ray tube lasts, which should be between 1,300 and 1,400 uses.

Allwood, who shared an office with Hurowitz when they worked together at the Jet Propulsion Laboratory, said she approached him when she started assembling a team.

Finding life on Mars would answer a question that has intrigued those on Earth for thousands of years, Allwood said. Such Martian life would indicate that “we’re not alone. There was life and it was next door,” she said.

Rachel Caston looks at lunar soil simulant JSC1A. Photo by Upasna Thapar

By Daniel Dunaief

It’s the ultimate road trip into the unknown. Space travel holds out the possibility of exploring strange new worlds, boldly going where no one has gone before (to borrow from a popular TV show).

While the excitement of such long-distance journeys inspires people, the National Aeronautics and Space Administration, among other agencies, is funding scientific efforts to ensure that anyone donning a spacesuit and jetting away from the blue planet is prepared for all the challenges to mind and body that await.

Rachel Caston, recently completed her doctorate, which included work at Stony Brook University in the laboratory of Bruce Demple for a project that explored the genetic damage lunar soil simulants have on human lung cells and on mouse brain cells.

Geologist Harrison Schmitt, who was the Apollo 17 lunar module pilot, shared symptoms he described as “lunar hay fever,” which included the types of annoyances people with allergies have to deal with during the spring: sore throat, sneezing and watery eyes.

Using simulated lunar soil because actual soil from the moon is too scarce, Caston found that several different types of soil killed the cell or damaged the cell’s genes, or DNA for both human lung and mouse brain cells.

While there has been considerable research that explores the inflammation response to soil, “there wasn’t any research previously done that I know of [that connected] lunar soil and DNA damage,” said Caston, who was the lead author on research published recently in the American Geophysical Union’s journal GeoHealth.

The moon’s soil becomes electrostatic due to radiation from the sun. Astronauts who walked on the moon, or did various explorations including digging into its surface, brought back some of that dust when it stuck to their space suits.

Caston sought to understand what causes damage to the DNA.

Going into the study, Demple, a professor of pharmacological sciences at SBU, suggested that they expected that the materials most capable of generating free radicals would also be the ones that exerted the greatest damage to the cells and their DNA. While free radicals may play a role, the action of dust simulants is more complex than that created by a single driving force.

Caston looked at the effect of five different types of simulants, which each represented a different aspect of lunar soil. One of the samples came from soil developed to test the ability of rovers to maneuver. Another one came from a lava flow in Colorado.

Demple said that the materials they used lacked space weather, which he suggested was an important feature of lunar soil. The surface of the moon is exposed constantly to solar wind, ultraviolet light and micrometeorites. The researchers mimicked the effect of micrometeorites by crushing the samples to smaller particle sizes, which increased their toxicity.

Farm to table: Caston eats ice cream and pets the cow that provided the milk for her frozen dessert at Cook’s Farm Dairy in Ortonville, Michigan. Photo by Carolyn Walls

In future experiments, the researchers plan to work with colleagues at the Department of Geosciences at SBU, including co-author Joel Hurowitz and other researchers at Brookhaven National Laboratory to mimic solar wind by exposing dust samples to high-energy atoms, which are the main component of solar wind. The scientists expect the treatment would cause the simulants to become more reactive, which they hope to test through experiments.

Caston credits Hurowitz , an assistant professor in the Department of Geosciences, with providing specific samples.

The samples are commonly used simulants for lunar rocks that mimic the chemical and mineral properties of the lunar highlands and the dark mare, Hurowitz explained.

“This has been a really fruitful collaboration between geology and medical science, and we’ll continue working together,” Hurowitz wrote in an email. They plan to look at similar simulants from asteroids and Mars in the future.

NASA has considered engineering solutions to minimize or eliminate astronaut’s exposure to dust. It might be difficult to eliminate all exposure for workers and explorers living some day on the moon for an extended period of time.

“The adherence of the dust to the space suits was a real problem, I think,” suggested Demple, adding that the next steps in this research will involve checking the role of the inflammatory response in the cytotoxicity, testing the effects of space weathering on toxicity and applying to NASA for actual samples of lunar regolith brought back by Apollo astronauts.

It took about two years of preliminary work to develop the methods to get consistency in their results, Demple said, and then another year of conducting research.

In addition to her work on lunar soil, Caston has studied DNA repair pathways in mitochondria. She used her expertise in that area for the DNA damage results they recently reported.

Caston, who is working as a postdoctoral researcher in Demple’s lab, is looking for a longer-term research opportunity either on Long Island or in Michigan, the two places where she’s lived for much of her life.

Caston lives in Smithtown with her husband Robert Caston, a software developer for Northrop Grumman. She earned her bachelor’s degree as well as her doctorate from Stony Brook University.

Her interest in science in general and genetics in particular took root at an early age, when she went with her father Kenneth Salatka, who worked at Parke Davis, a company Pfizer eventually bought. 

On April 23, 1997, she convinced her friend and her identical twin sister to attend a “fun with genetics” event.

Two of the people at her father’s company were using centrifuges to isolate DNA out of blood. “That was the coolest thing I ever saw,” she said. “I wanted to be a geneticist from that point on.” 

Her sister Madeline, who now sells insurance for Allstate, and her friend weren’t similarly impressed.

As for the work she did on lunar soil, Caston said she enjoys discussing the work with other people. “I like that I’m doing a project for NASA,” she said. “I’ve learned quite a bit about space travel.”