Searching for life on Mars and its moons

#life #Mars #moon #space #Extraterrestrial

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The scientific exploration of Mars over the past several decades has resulted in increasing evidence that the martian surface hosted habitable environments early in its history, as well as evidence of the building blocks of life in the form of organic molecules. Habitats on Mars that could harbor extant martian life have been hypothesized, such as subsurface environments, caves, and ice deposits. Mars is currently recognized as a “paleo-habitable” planet, reflecting its ancient habitability. Fully understanding the evolution of habitability and whether Mars has ever hosted life will be essential to understanding and exploring other extraterrestrial habitable environments and potential life-forms. Flagship missions of multiple space agencies in the 2020s will play essential and complementary roles and could finally provide an answer to these long-standing questions.

The planned Mars Sample-Return MSR mission of NASA and the European Space Agency should reveal more about the habitability of Mars by helping to determine the geologic evolution of Jezero crater and its surrounding areas, which are believed to be the site of an ancient lake see the photo. The Mars 2020 Perseverance rover will attempt to collect samples that will allow scientists to explore the evolution of Jezero crater and its habitability over time, as well as samples that may contain evidence of biosignatures. A high-priority science objective for MSR returned-sample science is to understand the habitability of Mars and look for potential signs of both extinct and extant life.

Mars is not alone because it has two small moons, Phobos and Deimos. Throughout the history of Mars, numerous asteroidal impacts on Mars have produced martian impact ejecta, and a fraction of the ejected material has been delivered to its moons. Phobos is closer to Mars, so it has more martian ejecta than Deimos. Numerical simulations show that >109 kg of martian material could be uniformly mixed in the regolith of Phobos the resultant martian fraction is >1000 parts per million.

Even if martian life-forms existed and could survive the transport to Phobos without suffering from impact-shock decomposition with a peak pressure of <5 GPa, the Phobos environment is highly inhospitable. Phobos does not have air or water, and its surface is constantly bathed in solar and galactic cosmic radiation. This indicates that martian materials on Phobos’ surface almost certainly do not contain any living microorganisms.

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Jezero crater on Mars is believed to be the site of an ancient lake. The Mars 2020 Perseverance rover aims to collect samples from the crater to analyze for evidence of life.

Instead, there may be dead biosignatures on Phobos, which we have called “SHIGAI” Sterilized and Harshly Irradiated Genes, and Ancient Imprints—the acronym in Japanese means “dead remains.” SHIGAI includes any potential microorganisms that could have been alive on Mars and were recently sterilized during or after the delivery to Phobos, and the microorganisms and biomarkers that had been processed on ancient Mars before the delivery to Phobos, including potential DNA fragments. The Mars-moon system is an ideal natural laboratory for the study of interplanetary transport and sustainability of SHIGAI on airless bodies in the Solar System.

Should a martian biosphere exist, any biosignatures or biomarkers observed in the samples from Jezero crater could be widespread elsewhere on Mars and possibly occur on the surface of Phobos. Because martian ejecta has been thoroughly delivered to Phobos by impact-driven random sampling, the biosignatures and biomarkers that may be contained in the Phobos regolith could reflect the diversity and evolution of a potential martian biosphere.

Martian Moons eXploration MMX, developed by the Japan Aerospace Exploration Agency, plans to collect a sample of >10 g from the Phobos surface and return to Earth in 2029. Detection of a “fingerprint” of martian life and SHIGAI should be achievable through comprehensive comparative studies using martian material from the Phobos surface and samples from Jezero crater returned by MMX and MSR, respectively.

The MSR samples have the potential to contain a variety of biomarker molecules e.g., lipids, such as hopanoids, sterols, and archaeols, and their diagenetic products. The sample could include modern living organisms from Jezero crater, if they are present. Of course, MSR could return samples without any evidence of life because of the focus on a single location. A distinct advantage for MMX is the ability to deliver martian materials derived from several regions. The random nature of the crater-forming impacts on Mars statistically delivers all possible martian materials, from sedimentary to igneous rocks that cover all of its geological eras.

Mutual international cooperation on MSR and MMX could answer questions such as how martian life, if present, emerged and evolved in time and place. If Mars never had life at all, these missions would then be absolutely vital in unraveling why Mars is lifeless and Earth has life. Therefore, the missions may eventually provide the means to decipher the divergent evolutionary paths of life on Mars and Earth.

Toward next-generation brain-computer interface systems

A new kind of neural interface system that coordinates the activity of hundreds of tiny brain sensors could one day deepen understanding of the brain and lead to new medical therapies

#Brain #BCI #computer #interface #sensor

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Close-up portrait of young and beautiful woman with the virtual futuristic glasses ( technology concept).Virtual holographic interface and young woman wearing glasses

Brain-computer interfaces (BCIs) are emerging assistive devices that may one day help people with brain or spinal injuries to move or communicate. BCI systems depend on implantable sensors that record electrical signals in the brain and use those signals to drive external devices like computers or robotic prosthetics.

Most current BCI systems use one or two sensors to sample up to a few hundred neurons, but neuroscientists are interested in systems that are able to gather data from much larger groups of brain cells.

Now, a team of researchers has taken a key step toward a new concept for a future BCI system — one that employs a coordinated network of independent, wireless microscale neural sensors, each about the size of a grain of salt, to record and stimulate brain activity. The sensors, dubbed “neurograins,” independently record the electrical pulses made by firing neurons and send the signals wirelessly to a central hub, which coordinates and processes the signals.

In a study published on August 12 in Nature Electronics, the research team demonstrated the use of nearly 50 such autonomous neurograins to record neural activity in a rodent.

The results, the researchers say, are a step toward a system that could one day enable the recording of brain signals in unprecedented detail, leading to new insights into how the brain works and new therapies for people with brain or spinal injuries.

“One of the big challenges in the field of brain-computer interfaces is engineering ways of probing as many points in the brain as possible,” said Arto Nurmikko, a professor in Brown’s School of Engineering and the study’s senior author. “Up to now, most BCIs have been monolithic devices — a bit like little beds of needles. Our team’s idea was to break up that monolith into tiny sensors that could be distributed across the cerebral cortex. That’s what we’ve been able to demonstrate here.”

The team, which includes experts from Brown, Baylor University, University of California at San Diego and Qualcomm, began the work of developing the system about four years ago. The challenge was two-fold, said Nurmikko, who is affiliated with Brown’s Carney Institute for Brain Science. The first part required shrinking the complex electronics involved in detecting, amplifying and transmitting neural signals into the tiny silicon neurograin chips. The team first designed and simulated the electronics on a computer, and went through several fabrication iterations to develop operational chips.

The second challenge was developing the body-external communications hub that receives signals from those tiny chips. The device is a thin patch, about the size of a thumb print, that attaches to the scalp outside the skull. It works like a miniature cellular phone tower, employing a network protocol to coordinate the signals from the neurograins, each of which has its own network address. The patch also supplies power wirelessly to the neurograins, which are designed to operate using a minimal amount of electricity.

“This work was a true multidisciplinary challenge,” said Jihun Lee, a postdoctoral researcher at Brown and the study’s lead author. “We had to bring together expertise in electromagnetics, radio frequency communication, circuit design, fabrication and neuroscience to design and operate the neurograin system.”

The goal of this new study was to demonstrate that the system could record neural signals from a living brain — in this case, the brain of a rodent. The team placed 48 neurograins on the animal’s cerebral cortex, the outer layer of the brain, and successfully recorded characteristic neural signals associated with spontaneous brain activity.

The team also tested the devices’ ability to stimulate the brain as well as record from it. Stimulation is done with tiny electrical pulses that can activate neural activity. The stimulation is driven by the same hub that coordinates neural recording and could one day restore brain function lost to illness or injury, researchers hope.

The size of the animal’s brain limited the team to 48 neurograins for this study, but the data suggest that the current configuration of the system could support up to 770. Ultimately, the team envisions scaling up to many thousands of neurograins, which would provide a currently unattainable picture of brain activity.

“It was a challenging endeavor, as the system demands simultaneous wireless power transfer and networking at the mega-bit-per-second rate, and this has to be accomplished under extremely tight silicon area and power constraints,” said Vincent Leung, an associate professor in the Department of Electrical and Computer Engineering at Baylor. “Our team pushed the envelope for distributed neural implants.”

There’s much more work to be done to make that complete system a reality, but researchers said this study represents a key step in that direction.

“Our hope is that we can ultimately develop a system that provides new scientific insights into the brain and new therapies that can help people affected by devastating injuries,” Nurmikko said.

Other co-authors on the research were Ah-Hyoung Lee (Brown), Jiannan Huang (UCSD), Peter Asbeck (UCSD), Patrick P. Mercier (UCSD), Stephen Shellhammer (Qualcomm), Lawrence Larson (Brown) and Farah Laiwalla (Brown). The research was supported by the Defense Advanced Research Projects Agency (N66001-17-C-4013).