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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
We’ve been talking about this for 2,000 years. Aristotle mentions it. And in our own time, scientists are designing experiments to figure out exactly what’s going on. But there’s no consensus yet.
Here’s what we do know.
The atmosphere isn’t magnifying the Moon. If anything, atmospheric refraction squashes it a little bit. And the Moon’s not closer to us at the horizon. It’s about 1.5 percent farther away. Also, it isn’t just the Moon. Constellations look huge on the horizon, too.
One popular idea is that this is a variation on the Ponzo illusion. Everything in our experience seems to shrink as it recedes toward the horizon — I mean clouds and planes and cars and ships. But the Moon doesn’t do that. So our minds make up a story to reconcile this inconsistency. Somehow the Moon gets bigger when it’s at the horizon. That’s one popular hypothesis, but there are others. And we’re still waiting for the experiment that will convince everyone that we understand this.
So why does the Moon look larger on the horizon? We don’t really know, but scientists are still trying to figure it out.
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Last Updated Feb 12, 2025 Related Terms
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By NASA
“I do evolutionary programming,” said NASA Goddard oceanographer Dr. John Moisan. “I see a lot of possibility in using evolutionary programming to solve many large problems we are trying to solve. How did life start and evolve? Can these processes be used to evolve intelligence or sentience?”Courtesy of John Moisan Name: John Moisan
Formal Job Classification: Research oceanographer
Organization: Ocean Ecology Laboratory, Hydrosphere, Biosphere, Geophysics (HBG), Earth Science Directorate (Code 616) – duty station at NASA’s Wallops Flight Facility on Virginia’s Eastern Shore
What do you do and what is most interesting about your role here at Goddard? How do you help support Goddard’s mission?
I develop ecosystem models and satellite algorithms to understand how the ocean’s ecology works. My work has evolved over time from when I coded ocean ecosystem models to the present where I now use artificial intelligence to evolve the ocean ecosystem models.
How did you become an oceanographer?
As a child, I watched a TV series called “Sea Hunt,” which involved looking for treasure in the ocean. It inspired me to want to spend my life scuba diving.
I got a Bachelor of Science in marine biology from the University of New England in Biddeford, Maine, and later got a Ph.D. from the Center for Coastal Physical Oceanography at Old Dominion University in Norfolk, Virginia.
Initially, I just wanted to do marine biology which to me meant doing lots of scuba diving, maybe living on a sailboat. Later, when I was starting my graduate schoolwork, I found a book about mathematical biology and a great professor who helped open my eyes to the world of numerical modeling. I found out that instead of scuba diving, I needed instead to spend my days behind a computer, learning how to craft ideas into equations and then code these into a computer to run simulations on ocean ecosystems.
I put myself through my initial education. I went to school fulltime, but I lived at home and hitchhiked to college on a daily basis. When I started my graduate school, I worked to support myself. I was in school during the normal work week, but from Friday evening through Sunday night, I worked 40 hours at a medical center cleaning and sterilizing the operating room instrument carts. This was during the height of the AIDS epidemic.
What was most exciting about your two field trips to the Antarctic?
In 1987, I joined a six-week research expedition to an Antarctic research station to explore how the ozone hole was impacting phytoplankton. These are single-celled algae that are responsible for making half the oxygen we breathe. Traveling to Antarctica is like visiting another planet. There are more types of blue than I’ve ever seen. It is an amazingly beautiful place to visit, with wild landscapes, glaciers, mountains, sea ice, and a wide range of wildlife. After my first trip I returned home and went back in a few months later as a biologist on a joint Polish–U.S. (National Oceanic and Atmospheric Administration) expedition to carry out a biological survey and measure how much fast the phytoplankton was growing in different areas of the Southern Ocean. We used nets to measure the amounts of fish and shrimp and took water samples to measure salinity, the amount of algae and their growth rates. We ate well, for example the Polish cook made up a large batch of smoked ice fish.
What other field work have you done?
While a graduate student, I helped do some benthic work in the Gulf of Maine. This study was focused on understanding the rates of respiration in the muds on the bottom of the ocean and on understanding how much biomass was in the muds. The project lowered a benthic grab device to the bottom where it would push a box core device into the sediments to return it to the surface. This process is sort of like doing a biopsy of the ocean bottom.
What is your goal as a research oceanographer at Goddard?
Ocean scientists measure the amount and variability of chlorophyll a, a pigment in algae, in the ocean because it is an analogue to the amount of algae or phytoplankton in the ocean. Chlorophyll a is used to capture solar energy to make sugars, which the algae use for growth. Generally, areas of the ocean that have more chlorophyll are also areas where growth or primary production is higher. So, by estimating how much chlorophyll is in the ocean we can study how these processes are changing with an aim in understanding why. NASA uses the color of the ocean using satellites to estimate chlorophyll a because chlorophyll absorbs sunlight and changes the color of the ocean. Algae have other kinds of pigments, each of which absorbs light at different wavelengths. Because different groups of algae have different levels of pigments, they are like fingerprints that can reveal the type of algae in the water. Some of my research aims at trying to use artificial intelligence and mathematical techniques to create new ways to measure these pigments from space to understand how ocean ecosystems change.
In 2024, NASA plans to launch the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite, which will measure the color of the ocean at many different wavelengths. The data from this satellite can be used with results from my work on genetic programs and inverse modeling to estimate concentrations of different pigments and possibly concentrations of different types of algae in the ocean.
You have been at Goddard over 22 years. What is most memorable to you?
I develop ecosystem models. But ecosystems do not have laws in the same way that physics has laws. Equations need to be created so that the ecosystem models represent what is observed in the real world. Satellites have been a great source for those observations, but without a lot of other types of observations that are collected in the field, the ocean, it is difficult to develop these equations. In my time at NASA, I have only been able to develop models because of the great but often tedious work that ocean scientists around the world have been doing when they go on ocean expeditions to measure various ocean features, be it simple temperature or the more complicated measurements of algal growth rates. My experience with their willingness to collaborate and share data is especially memorable. This experience is also what I enjoyed with numerous scientists at NASA who have always been willing to support new ideas and point me in the right direction. It has made working at NASA a phenomenal experience.
What are the philosophical implications of your work?
The human capacity to think rapidly, to test and change our opinions based on what we learn, is slow compared to that of a computer. Computers can help us adapt more quickly. I can put 1,000 students in a room developing ecosystem model models. But I know that this process of developing ecosystem models is slow when compared what a computer can do using an artificial intelligence approach called genetic programming, it is a much faster way to generate ecosystem model solutions.
Philosophically, there is no real ecosystem model that is the best. Life and ecosystems on Earth change and adapt at rates too fast for any present-day model to resolve, especially considering climate change. The only real ecosystem model is the reality itself. No computer model can perfectly simulate ecosystems. By utilizing the fast adaptability that evolutionary computer modeling techniques provide, simulating and ultimately predicting ecosystems can be improved greatly.
How does your work have implications for scientists in general?
I do evolutionary programming. I see a lot of possibility in using evolutionary programming to solve many large problems we are trying to solve. How did life start and evolve? Can these processes be used to evolve intelligence or sentience?
The artificial intelligence (AI) work answers questions, but you need to identify the questions. This is the greater problem when it comes to working with AI. You cannot answer the question of how to create a sentient life if you do not know how to define it. If I cannot measure life, how can I model it? I do not know how to write that equation. How does life evolve? How did the evolutionary process start? These are big questions I enjoy discussing with friends. It can be as frustrating as contemplating “nothing.”
Who inspires you?
Many of the scientists that I was fortunate to work with at various research institutes, such as Scripps Institution of Oceanography at the University of California, San Diego. These are groups of scientists are open to always willing to share their ideas. These are individuals who enjoy doing science. I will always be indebted to them for their kindness in sharing of ideas and data.
Do you still scuba dive?
Yes, I wish I could dive daily, it is a very calming experience. I’m trying to get my kids to join me.
What else do you do for fun?
My wife and I bike and travel. Our next big bike trip will hopefully be to Shangri-La City in China. I also enjoy sailing and trying to grow tropical plants. But, most of all, I enjoy helping raise my children to be resilient, empathic, and intelligent beings.
What are your words to live by?
Life. So much to see. So little time.
Conversations With Goddard is a collection of question and answer profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage. Conversations With Goddard is a collection of Q&A profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage.
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Last Updated Feb 10, 2025 EditorJessica EvansContactRob Garnerrob.garner@nasa.gov Related Terms
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By European Space Agency
Last night a crucial step in the European Space Agency’s eclipse-making Proba-3 mission was completed: the two spacecraft, flying jointly since launch, have successfully separated. This leaves them ready to begin their cosmic dance in the world’s first-ever precision formation-flying mission.
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
An equal collaboration between NASA and the Indian Space Research Organisation, NISAR will offer unprecedented insights into Earth’s constantly changing land and ice surfaces using synthetic aperture radar technology. The spacecraft, depicted here in an artist’s concept, will launch from India.NASA/JPL-Caltech A Q&A with the lead U.S. scientist of the mission, which will track changes in everything from wetlands to ice sheets to infrastructure damaged by natural disasters.
The upcoming U.S.-India NISAR (NASA-ISRO Synthetic Aperture Radar) mission will observe Earth like no mission before, offering insights about our planet’s ever-changing surface.
The NISAR mission is a first-of-a-kind dual-band radar satellite that will measure land deformation from earthquakes, landslides, and volcanoes, producing data for science and disaster response. It will track how much glaciers and ice sheets are advancing or retreating and it will monitor growth and loss of forests and wetlands for insights on the global carbon cycle.
As diverse as NISAR’s impact will be, the mission’s winding path to launch — in a few months’ time — has also been remarkable. Paul Rosen, NISAR’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California, has been there at every step. He recently discussed the mission and what sets it apart.
NISAR Project Scientist Paul Rosen of NASA’s Jet Propulsion Laboratory first traveled to India in late 2011 to discuss collaboration with ISRO scientists on an Earth-observing radar mission. NASA and ISRO signed an agreement in 2014 to develop NISAR. NASA/JPL-Caltech How will NISAR improve our understanding of Earth?
The planet’s surfaces never stop changing — in some ways small and subtle, and in other ways monumental and sudden. With NISAR, we’ll measure that change roughly every week, with each pixel capturing an area about half the size of a tennis court. Taking imagery of nearly all Earth’s land and ice surfaces this frequently and at such a small scale — down to the centimeter — will help us put the pieces together into one coherent picture to create a story about the planet as a living system.
What sets NISAR apart from other Earth missions?
NISAR will be the first Earth-observing satellite with two kinds of radar — an L-band system with a 10-inch (25-centimeter) wavelength and an S-band system with a 4-inch (10-centimeter) wavelength.
Whether microwaves reflect or penetrate an object depends on their wavelength. Shorter wavelengths are more sensitive to smaller objects such as leaves and rough surfaces, whereas longer wavelengths are more reactive with larger structures like boulders and tree trunks.
So NISAR’s two radar signals will react differently to some features on Earth’s surface. By taking advantage of what each signal is or isn’t sensitive to, researchers can study a broader range of features than they could with either radar on its own, observing the same features with different wavelengths.
Is this new technology?
The concept of a spaceborne synthetic aperture radar, or SAR, studying Earth’s processes dates to the 1970s, when NASA launched Seasat. Though the mission lasted only a few months, it produced first-of-a-kind images that changed the remote-sensing landscape for decades to come.
It also drew me to JPL in 1981 as a college student: I spent two summers analyzing data from the mission. Seasat led to NASA’s Shuttle Imaging Radar program and later to the Shuttle Radar Topography Mission.
What will happen to the data from the mission?
Our data products will fit the needs of users across the mission’s science focus areas — ecosystems, cryosphere, and solid Earth — plus have many uses beyond basic research like soil-moisture and water resources monitoring.
We’ll make the data easily accessible. Given the volume of the data, NASA decided that it would be processed and stored in the cloud, where it’ll be free to access.
How did the ISRO partnership come about?
We proposed DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice), an L-band satellite, following the 2007 Decadal Survey by the National Academy of Sciences. At the time, ISRO was exploring launching an S-band satellite. The two science teams proposed a dual-band mission, and in 2014 NASA and ISRO agreed to partner on NISAR.
Since then, the agencies have been collaborating across more than 9,000 miles (14,500 kilometers) and 13 time zones. Hardware was built on different continents before being assembled in India to complete the satellite. It’s been a long journey — literally.
More About NISAR
The NISAR mission is an equal collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on hardware development for an Earth-observing mission. Managed for the agency by Caltech, JPL leads the U.S. component of the project and is providing the mission’s L-band SAR. NASA is also providing the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem.
Space Applications Centre Ahmedabad, ISRO’s lead center for payload development, is providing the mission’s S-band SAR instrument and is responsible for its calibration, data processing, and development of science algorithms to address the scientific goals of the mission. U R Rao Satellite Centre in Bengaluru, which leads the ISRO components of the mission, is providing the spacecraft bus. The launch vehicle is from ISRO’s Vikram Sarabhai Space Centre, launch services are through ISRO’s Satish Dhawan Space Centre, and satellite mission operations are by ISRO Telemetry Tracking and Command Network. National Remote Sensing Centre in Hyderabad is primarily responsible for S-band data reception, operational products generation, and dissemination.
To learn more about NISAR, visit:
https://nisar.jpl.nasa.gov
News Media Contacts
Andrew Wang / Jane J. Lee
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 / 818-354-0307
andrew.wang@jpl.nasa.gov / jane.j.lee@jpl.nasa.gov
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Last Updated Jan 06, 2025 Related Terms
NISAR (NASA-ISRO Synthetic Aperture Radar) Climate Change Earth Earth Science Earth Science Division Ice & Glaciers Jet Propulsion Laboratory Seasat Shuttle Radar Topography Mission (SRTM) SIR-C/X-SAR (Shuttle Imaging Radar-C / X-Band Synthetic Aperture Radar) Explore More
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