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Earth from Space: Easter egg hunt
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By NASA
Scientists find that cometary dust affects interpretation of spacecraft measurements, reopening the case for comets like 67P as potential sources of water for early Earth.
Researchers have found that water on Comet 67P/Churyumov–Gerasimenko has a similar molecular signature to the water in Earth’s oceans. Contradicting some recent results, this finding reopens the case that Jupiter-family comets like 67P could have helped deliver water to Earth.
Water was essential for life to form and flourish on Earth and it remains central for Earth life today. While some water likely existed in the gas and dust from which our planet materialized around 4.6 billion years ago, much of the water would have vaporized because Earth formed close to the Sun’s intense heat. How Earth ultimately became rich in liquid water has remained a source of debate for scientists.
Research has shown that some of Earth’s water originated through vapor vented from volcanoes; that vapor condensed and rained down on the oceans. But scientists have found evidence that a substantial portion of our oceans came from the ice and minerals on asteroids, and possibly comets, that crashed into Earth. A wave of comet and asteroid collisions with the solar system’s inner planets 4 billion years ago would have made this possible.
This image, taken by ESA’s Rosetta navigation camera, was taken from a about 53 miles from the center of Comet 67P/Churyumov-Gerasimenko on March 14, 2015. The image resolution is 24 feet per pixel and is cropped and processed to bring out the details of the comet’s activity. ESA/Rosetta/NAVCAM While the case connecting asteroid water to Earth’s is strong, the role of comets has puzzled scientists. Several measurements of Jupiter-family comets — which contain primitive material from the early solar system and are thought to have formed beyond the orbit of Saturn — showed a strong link between their water and Earth’s. This link was based on a key molecular signature scientists use to trace the origin of water across the solar system.
This signature is the ratio of deuterium (D) to regular hydrogen (H) in the water of any object, and it gives scientists clues about where that object formed. Deuterium is a rare, heavier type — or isotope — of hydrogen. When compared to Earth’s water, this hydrogen ratio in comets and asteroids can reveal whether there’s a connection.
Because water with deuterium is more likely to form in cold environments, there’s a higher concentration of the isotope on objects that formed far from the Sun, such as comets, than in objects that formed closer to the Sun, like asteroids.
Measurements within the last couple of decades of deuterium in the water vapor of several other Jupiter-family comets showed similar levels to Earth’s water.
“It was really starting to look like these comets played a major role in delivering water to Earth,” said Kathleen Mandt, planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Mandt led the research, published in Science Advances on Nov. 13, that revises the abundance of deuterium in 67P.
About Kathleen Mandt
But in 2014, ESA’s (European Space Agency) Rosetta mission to 67P challenged the idea that Jupiter-family comets helped fill Earth’s water reservoir. Scientists who analyzed Rosetta’s water measurements found the highest concentration of deuterium of any comet, and about three times more deuterium than there is in Earth’s oceans, which have about 1 deuterium atom for every 6,420 hydrogen atoms.
“It was a big surprise and it made us rethink everything,” Mandt said.
Mandt’s team decided to use an advanced statistical-computation technique to automate the laborious process of isolating deuterium-rich water in more than 16,000 Rosetta measurements. Rosetta made these measurements in the “coma” of gas and dust surrounding 67P. Mandt’s team, which included Rosetta scientists, was the first to analyze all of the European mission’s water measurements spanning the entire mission.
The researchers wanted to understand what physical processes caused the variability in the hydrogen isotope ratios measured at comets. Lab studies and comet observations showed that cometary dust could affect the readings of the hydrogen ratio that scientists detect in comet vapor, which could change our understanding of where comet water comes from and how it compares to Earth’s water.
What are comets made of? It’s one of the questions ESA’s Rosetta mission to comet 67P/Churyumov-Gerasimenko wanted to answer. “So I was just curious if we could find evidence for that happening at 67P,” Mandt said. “And this is just one of those very rare cases where you propose a hypothesis and actually find it happening.”
Indeed, Mandt’s team found a clear connection between deuterium measurements in the coma of 67P and the amount of dust around the Rosetta spacecraft, showing that the measurements taken near the spacecraft in some parts of the coma may not be representative of the composition of a comet’s body.
As a comet moves in its orbit closer to the Sun, its surface warms up, causing gas to release from the surface, including dust with bits of water ice on it. Water with deuterium sticks to dust grains more readily than regular water does, research suggests. When the ice on these dust grains is released into the coma, this effect could make the comet appear to have more deuterium than it has.
Mandt and her team reported that by the time dust gets to the outer part of the coma, at least 75 miles from the comet body, it is dried out. With the deuterium-rich water gone, a spacecraft can accurately measure the amount of deuterium coming from the comet body.
This finding, the paper authors say, has big implications not only for understanding comets’ role in delivering Earth’s water, but also for understanding comet observations that provide insight into the formation of the early solar system.
“This means there is a great opportunity to revisit our past observations and prepare for future ones so we can better account for the dust effects,” Mandt said.
By Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Dec 03, 2024 Editor Lonnie Shekhtman Contact Lonnie Shekhtman lonnie.shekhtman@nasa.gov Location Goddard Space Flight Center Related Terms
Comets Goddard Space Flight Center Planetary Science Planetary Science Division Rosetta Science Mission Directorate The Solar System View the full article
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By European Space Agency
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By European Space Agency
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Aaron Yazzie’s dream of being part of humanity’s exploration of space took him on a journey from his childhood home on the Navajo Nation to working at NASA’s Jet Propulsion Laboratory (JPL) in Southern California. His journey reflects not only his personal ambition, but also a commitment to elevating Indigenous representation in science, technology, engineering, and mathematics (STEM) fields.
“Getting an internship at NASA was the culmination of a lot of work done by myself, and many of the Indigenous trailblazers that came before me, to make a path and a space for Indigenous peoples at places where there might not have been any Indigenous Peoples in any rooms,” said Yazzie.
Born in Tuba City, Arizona, Yazzie is of the Salt Clan and born for the Bitter Water Clan, which reflect his maternal and paternal lineage, respectively. The Navajo clan system communicates family heritage and where their families come from.
Yazzie’s path to NASA began with a passion for engineering, which he pursued at Stanford University in Stanford, California, where he earned a bachelor’s degree in mechanical engineering in 2008. NASA is a dream job for many, from artists to engineers, and Yazzie was no exception. Securing an internship at NASA’s Jet Propulsion Laboratory in 2008 marked a significant milestone for him, particularly as an Indigenous person in STEM where Indigenous people are underrepresented. Throughout his academic and professional journey, he frequently found himself as the only Indigenous voice in the room with Indigenous people representing less than 0.6% of the American STEM workforce.
Yazzie’s work at NASA is deeply intertwined with his cultural identity. In the Navajo culture, traditional stories tell how the Diné (the people) came to exist in Dinétah (Navajo homelands).
Yazzie’s contributions to missions exploring Mars, including testing the Curiosity Rover’s sample acquisition system and developing drill bits for the Perseverance Rover, resonate with the Navajo creation story, which emphasizes nurturing life on a developing Earth—paralleling his efforts to support the possibility of life on Mars. He approaches his role with a sense of purpose, reflecting on the importance of understanding origins–both of the Earth and of life itself.
“By studying Mars, we learn about how rocky, terrestrial planets, like Mars and Earth, formed over billions of years,” said Yazzie, “And by searching for ancient microbial life on Mars, we might learn how life on Earth originated. I am proud to be doing what my ancestors have been doing before me.”
Emphasizing a commitment to lifelong learning, Yazzie advises future interns to “embrace the opportunities of growth and learning that come with working at NASA.” His advice: learn how to be a good learner. Yazzie’s diverse responsibilities, from test engineer to systems engineer, keep him engaged and continuously evolving.
“I think I am most proud of the outreach work I have been able to do, especially to Indigenous communities,” said Yazzie, “I want to help Indigenous students understand that they can exist and thrive at places like NASA.”
Yazzie’s work has been recognized with awards from NASA JPL, Stanford University, and his own tribe, reinforcing his role as a trailblazer for generations. As he continues to contribute to humanity’s understanding of Mars and its potential for past life, he honors his ancestors by paving the way for a more inclusive future in space exploration. Through his work, Yazzie inspires a new generation of Diné scientists and engineers, proving their voices have an essential place in the story of the cosmos.
Like Yazzie, NASA is devoted to mentoring the next generation of Indigenous doers, thinkers, and innovators. Anyone interested in following his footsteps may consider applying for a NASA Internship. Outside of internships NASA offers numerous routes to help Indigenous students get involved with STEM. Additionally, through NASA’s Minority University Research and Education Project (MUREP), the agency provides financial assistance via competitive awards to Minority Serving Institutions. The MUREP American Indian and Alaska Native STEM Engagement (MAIANSE) program offers funding dedicated to supporting Indigenous students launch their careers at NASA.
Want to learn more about interns at NASA? Read More View the full article
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