NASA Astronomy Picture of the Day

October 10, 2024

Five Bright Comets from SOHO

Five bright comets are compared in these panels, recorded by a coronograph on board the long-lived, sun-staring SOHO spacecraft. Arranged chronologically all are recognizable by their tails streaming away from the Sun at the center of each field of view, where a direct view of the overwhelmingly bright Sun is blocked by the coronagraph's occulting disk. Each comet was memorable for earthbound skygazers, starting at top left with Comet McNaught, the 21st century's brightest comet (so far). C/2023 A3 Tsuchinshan-Atlas, approaching its perihelion with the active Sun at bottom center, has most recently grabbed the attention of comet watchers around the globe. By the end of October 2024, the blank 6th panel may be filled with bright sungrazer comet C/2024 S1 Atlas. … or not.

https://apod.nasa.gov/apod/astropix.html

NASA's Hubble Watches Jupiter's Great Red Spot Behave Like a Stress Ball

October 09, 2024 2:15PM

Titanic Storm Wiggles Like a Plate of Gelatin

Jupiter's birthmark is an unbelievably huge storm that’s mysteriously crimson red in color. It looks like a bloodshot cycloptic eye staring back at Earth.

The anticyclone churns along a southern mid-latitude cloud belt and has survived in Jupiter's turbulent atmosphere for at least 150 years.

What’s mind-numbing is that the Great Red Spot (GRS) is big enough to swallow our entire planet, making it the largest storm in the solar system.

Astronomers need Hubble's keen vision to keep an eye on the GRS's behavior, like a weatherman watching a spinning hurricane.

This is done only once per year under the Outer Planet Atmospheres Legacy program (OPAL), but a new program has enabled Hubble to capture eight views of the spot over a 90-day period.

And there are always new surprises.

For 90 days between December 2023 and March 2024, a collection of Hubble photos reveal that the GRS is not as stable as it might look.

Its elliptical shape can change dimensions – looking like a slightly skinnier or fatter red oval. This shape-shifting is unexpected and unexplained.

But in hindsight, this might not be a total surprise considering that Jupiter’s atmosphere is ever-changing with dynamic winds.

It's like trying to predict the exact motion of a swirl of creamer poured into a cup of coffee.

Does the meteorology on giant planets around other stars have their own immense storms? Hubble's detailed look at Jupiter might offer new clues.

Astronomers have observed Jupiter's legendary Great Red Spot (GRS), an anticyclone large enough to swallow Earth, for at least 150 years.

But there are always new surprises – especially when NASA's Hubble Space Telescope takes a close-up look at it.

Hubble's new observations of the famous red storm, collected 90 days between December 2023 to March 2024, reveal that the GRS is not as stable as it might look.

The recent data show the GRS jiggling like a bowl of gelatin. The combined Hubble images allowed astronomers to assemble a time-lapse movie of the squiggly behavior of the GRS.

"While we knew its motion varies slightly in its longitude, we didn't expect to see the size oscillate as well.

As far as we know, it's not been identified before," said Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Maryland, lead author of the science paper published in The Planetary Science Journal.

"This is really the first time we've had the proper imaging cadence of the GRS. With Hubble's high resolution we can say that the GRS is definitively squeezing in and out at the same time as it moves faster and slower.

That was very unexpected, and at present there are no hydrodynamic explanations."

Hubble monitors Jupiter and the other outer solar system planets every year through the Outer Planet Atmospheres Legacy program (OPAL) led by Simon, but these observations were from a program dedicated to the GRS.

Understanding the mechanisms of the largest storms in the solar system puts the theory of hurricanes on Earth into a broader cosmic context, which might be applied to better understanding the meteorology on planets around other stars.

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Simon's team used Hubble to zoom in on the GRS for a detailed look at its size, shape, and any subtle color changes.

"When we look closely, we see a lot of things are changing from day to day," said Simon.

This includes ultraviolet-light observations showing that the distinct core of the storm gets brightest when the GRS is at its largest size in its oscillation cycle.

This indicates less haze absorption in the upper atmosphere.

"As it accelerates and decelerates, the GRS is pushing against the windy jet streams to the north and south of it," said co-investigator Mike Wong of the University of California at Berkeley.

"It's similar to a sandwich where the slices of bread are forced to bulge out when there's too much filling in the middle."

Wong contrasted this to Neptune, where dark spots can drift wildly in latitude without strong jet streams to hold them in place.

Jupiter's Great Red Spot has been held at a southern latitude, trapped between the jet streams, for the extent of Earth-bound telescopic observations.

The team has continued watching the GRS shrink since the OPAL program began 10 years ago. They predict it will keep shrinking before taking on a stable, less-elongated, shape.

"Right now it's over-filling its latitude band relative to the wind field. Once it shrinks inside that band the winds will really be holding it in place," said Simon.

The team predicts that the GRS will probably stabilize in size, but for now Hubble only observed it for one oscillation cycle.

The researchers hope that in the future other high-resolution images from Hubble might identify other Jovian parameters that indicate the underlying cause of the oscillation.

https://hubblesite.org/contents/news-releases/2024/news-2024-011

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https://science.nasa.gov/missions/hubble/nasas-hubble-new-horizons-team-up-for-a-simultaneous-look-at-uranus/

NASA’s Hubble, New Horizons Team Up for a Simultaneous Look at Uranus

Oct 09, 2024

NASA's Hubble Space Telescope and New Horizons spacecraft simultaneously set their sights on Uranus recently, allowing scientists to make a direct comparison of the planet from two very different viewpoints.

The results inform future plans to study like types of planets around other stars.

Astronomers used Uranus as a proxy for similar planets beyond our solar system, known as exoplanets, comparing high-resolution images from Hubble to the more-distant view from New Horizons.

This combined perspective will help scientists learn more about what to expect while imaging planets around other stars with future telescopes.

"While we expected Uranus to appear differently in each filter of the observations, we found that Uranus was actually dimmer than predicted in the New Horizons data taken from a different viewpoint," said lead author Samantha Hasler of the Massachusetts Institute of Technology in Cambridge and New Horizons science team collaborator.

Direct imaging of exoplanets is a key technique for learning about their potential habitability, and offers new clues to the origin and formation of our own solar system.

Astronomers use both direct imaging and spectroscopy to collect light from the observed planet and compare its brightness at different wavelengths.

However, imaging exoplanets is a notoriously difficult process because they're so far away. Their images are mere pinpoints and so are not as detailed as the close-up views that we have of worlds orbiting our Sun.

Researchers can also only directly image exoplanets at "partial phases," when only a portion of the planet is illuminated by their star as seen from Earth.

Uranus was an ideal target as a test for understanding future distant observations of exoplanets by other telescopes for a few reasons.

First, many known exoplanets are also gas giants similar in nature. Also, at the time of the observations, New Horizons was on the far side of Uranus, 6.5 billion miles away, allowing its twilight crescent to be studied—something that cannot be done from Earth.

At that distance, the New Horizons view of the planet was just several pixels in its color camera, called the Multispectral Visible Imaging Camera.

On the other hand, Hubble, with its high resolution, and in its low-Earth orbit 1.7 billion miles away from Uranus, was able to see atmospheric features such as clouds and storms on the day side of the gaseous world.

"Uranus appears as just a small dot on the New Horizons observations, similar to the dots seen of directly-imaged exoplanets from observatories like Webb or ground-based observatories," added Hasler.

"Hubble provides context for what the atmosphere is doing when it was observed with New Horizons."

The gas giant planets in our solar system have dynamic and variable atmospheres with changing cloud cover. How common is this among exoplanets?

By knowing the details of what the clouds on Uranus looked like from Hubble, researchers are able to verify what is interpreted from the New Horizons data.

In the case of Uranus, both Hubble and New Horizons saw that the brightness did not vary as the planet rotated, which indicates that the cloud features were not changing with the planet’s rotation.

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However, the importance of the detection by New Horizons has to do with how the planet reflects light at a different phase than what Hubble, or other observatories on or near Earth, can see.

New Horizons showed that exoplanets may be dimmer than predicted at partial and high phase angles, and that the atmosphere reflects light differently at partial phase.

NASA has two major upcoming observatories in the works to advance studies of exoplanet atmospheres and potential habitability.

“These landmark New Horizons studies of Uranus from a vantage point unobservable by any other means add to the mission’s treasure trove of new scientific knowledge, and have, like many other datasets obtained in the mission, yielded surprising new insights into the worlds of our solar system,” added New Horizons principal investigator Alan Stern of the Southwest Research Institute.

NASA's upcoming Nancy Grace Roman Space Telescope, set to launch by 2027, will use a coronagraph to block out a star’s light to directly see gas giant exoplanets.

NASA’s Habitable Worlds Observatory, in an early planning phase, will be the first telescope designed specifically to search for atmospheric biosignatures on Earth-sized, rocky planets orbiting other stars.

“Studying how known benchmarks like Uranus appear in distant imaging can help us have more robust expectations when preparing for these future missions,” concluded Hasler. “And that will be critical to our success.”

Launched in January 2006, New Horizons made the historic flyby of Pluto and its moons in July 2015, before giving humankind its first close-up look at one of these planetary building block and Kuiper Belt object, Arrokoth, in January 2019.

New Horizons is now in its second extended mission, studying distant Kuiper Belt objects, characterizing the outer heliosphere of the Sun, and making important astrophysical observations from its unmatched vantage point in distant regions of the solar system.

The Uranus results are being presented this week at the 56th annual meeting of the American Astronomical Society Division for Planetary Sciences, in Boise, Idaho.

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Artemis I Radiation Measurements Validate Orion Safety for Astronauts

Oct 09, 2024

NASA’s Orion spacecraft is designed to keep astronauts safe in deep space, protecting them from the unforgiving environment far from Earth.

During the uncrewed Artemis I mission, researchers from NASA, along with several collaborators, flew payloads onboard Orion to measure potential radiation exposure to astronauts.

Radiation measurements were taken inside Orion by 5,600 passive sensors and 34 active radiation detectors during its 25.5-day mission around the Moon and back, which provided important data on exposure within the Earth’s Van Allen radiation belt.

These detailed findings were published in a recent scientific article through a collaborative effort by NASA’s Space Radiation Analysis Group, the DLR (German Space Center), and ESA (European Space Agency).

The measurements show that while radiation exposure can vary depending on location within Orion, the spacecraft can protect its crew from potentially hazardous radiation levels during lunar missions.

Space radiation could pose major risks to long-duration human space flights, and the findings from the Artemis I mission represent a crucial step toward future human exploration beyond low Earth orbit, to the Moon, and eventually to Mars.

NASA’s HERA (Hybrid Electronic Radiation Assessor) and Crew Active Dosimeter, which were tested previously on the International Space Station, and ESA’s Active Dosimeter, were among the instruments used to measure radiation inside Orion.

HERA’s radiation sensor can warn crew members need to take shelter in the case of a radiation event, such as a solar flare.

The Crew Active Dosimeter can collect real-time radiation dose data for astronauts and transmit it back to Earth for monitoring.

Radiation measurements were conducted in various areas of the spacecraft, each offering different levels of shielding.

In addition, the Matroshka AstroRad Radiation Experiment, a collaboration between NASA and DLR, involved radiation sensors placed on and inside two life-sized manikin torsos to simulate the impact of radiation on human tissue.

These manikins enabled measurements of radiation doses on various body parts, providing valuable insight into how radiation may affect astronauts traveling to deep space.

Researchers found that Orion’s design can protect its crew from potentially hazardous radiation levels during lunar missions.

Though the spacecraft’s radiation shielding is effective, the range of exposure can greatly vary based on spacecraft orientation in specific environments.

When Orion altered its orientation during an engine burn of the Interim Cryogenic Propulsion Stage, radiation levels dropped nearly in half due to the highly directional nature of the radiation in the Van Allen belt.

“These radiation measurements show that we have an effective strategy for managing radiation risks in the Orion spacecraft.

However, key challenges remain, especially for long-duration spaceflights and the protection of astronauts on spacewalks,” said Stuart George, NASA’s lead author on the paper.

NASA’s long-term efforts and research in mitigating space radiation risks are ongoing, as radiation measurements on future missions will depend heavily on spacecraft shielding, trajectory, and solar activity.

The same radiation measurement hardware flown on Artemis I will support the first crewed Artemis mission around the Moon, Artemis II, to better understand the radiation exposure seen inside Orion and ensure astronaut safety to the Moon and beyond.

https://www.nasa.gov/missions/artemis/artemis-1/artemis-i-radiation-measurements-validate-orion-safety-for-astronauts/

NASA Terminal Transmits First Laser Communications Uplink to Space

Oct 09, 2024

NASA’s LCOT (Low-Cost Optical Terminal), a ground station made of modified commercial hardware, transmitted its first laser communications uplink to the TBIRD (TeraByte Infrared Delivery), a tissue box-sized payload formerly in low Earth orbit.

During the first live sky test, NASA’s LCOT produced enough uplink intensity for the TBIRD payload to identify the laser beacon, connect, and maintain a connection to the ground station for over three minutes.

This successful test marks an important achievement for laser communications: connecting LCOT’s laser beacon from Earth to TBIRD required one milliradian of pointing accuracy, the equivalent of hitting a three-foot target from over eight American football fields away.

The test was one of many laser communications achievements TBIRD made possible during its successful, two-year mission.

Prior to its mission completion on Sept. 15, 2024, the payload transmitted at a record-breaking 200 gigabits per second.

In an actual use case, TBIRD’s three-minute connection time with LCOT would be sufficient to return over five terabytes of critical science data, the equivalent of over 2,500 hours of high-definition video in a single pass.

As the LCOT sky test demonstrates, the ultra-high-speed capabilities of laser communications will allow science missions to maintain their connection to Earth as they travel farther than ever before.

NASA’s SCaN (Space Communications and Navigation) program office is implementing laser communications technology in various orbits, including the upcoming Artemis II mission, to demonstrate its potential impact in the agency’s mission to explore, innovate, and inspire discovery.

“Optical, or laser, communications can transfer 10 to 100 times more data than radio frequency waves,” said Kevin Coggins, deputy associate administrator and SCaN program manager.

“Literally, it’s the wave of the future, as it’ll enable scientists to realize an ever-increasing amount of data from their missions and will serve as our critical lifeline for astronauts traveling to and from Mars.”

Historically, space missions have used radio frequencies to send data to and from space, but with science instruments capturing more data, communications assets must meet increasing demand.

The infrared light used for laser communications transmits the data at a shorter wavelength than radio, meaning ground stations on Earth can send and receive more data per second.

The LCOT team continues to refine pointing capabilities through additional tests with NASA’s LCRD (Laser Communications Relay Demonstration).

As LCOT and the agency’s other laser communications missions continue to reach new milestones in connectivity and accessibility, they demonstrate laser communications’ potential to revolutionize scientists’ access to new data about Earth, our solar system, and beyond.

“It’s a testament to the hard work and skill of the entire team,” said Dr. Haleh Safavi, project lead for LCOT.

“We work with very complicated and sensitive transmission equipment that must be installed with incredible precision.

These results required expeditious planning and execution at every level.”

Experiments like TBIRD and LCRD are only two of SCaN’s multiple in-space demonstrations of laser communications, but a robust laser communications network relies on easily reconfigurable ground stations on Earth.

The LCOT ground station showcases how the government and aerospace industry can build and deploy flexible laser communications ground stations to meet the needs of a wide variety of NASA and commercial missions, and how these ground stations open new doors for communications technology and extremely high data volume transmission.

https://www.nasa.gov/technology/space-comms/space-communications/nasa-terminal-transmits-first-laser-communications-uplink-to-space/

https://www.nasa.gov/earth/nasa-funded-study-assesses-pollution-near-los-angeles-area-warehouses/

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GH001091

NASA-Funded Study Assesses Pollution Near Los Angeles-Area Warehouses

Oct 09, 2024

Satellite-based data offers a broad view of particulate air pollution patterns across a major West Coast e-commerce hub.

As goods of all shapes and sizes journey from factory to doorstep, chances are they’ve stopped at a warehouse along the way — likely several of them.

The sprawling structures are waypoints in the logistics networks that make e-commerce possible. Yet the convenience comes with tradeoffs, as illustrated in a recent NASA-funded study.

Published in the journal GeoHealth, the research analyzes patterns of particulate pollution in Southern California and found that ZIP codes with more or larger warehouses had higher levels of contaminants over time than those with fewer or smaller warehouses. Researchers focused on particulate pollution, choosing Southern California because it is a major distribution hub for goods: Its ports handle 40% of cargo containers entering the country.

The buildings themselves are not the major particulate sources. Rather, it’s the diesel trucks that pick up and drop off goods, emitting exhaust containing toxic particles called PM2.5.

At 2.5 micrometers or less, these pollutants can be inhaled into the lungs and absorbed into the bloodstream.

Although atmospheric concentrations are typically so small they’re measured in millionths of a gram per cubic meter, the authors caution that there’s no safe exposure level for PM2.5.

“Any increase in concentration causes some health damage,” said co-author Yang Liu, an environmental health researcher at Emory University in Atlanta.

“But if you can curb pollution, there will be a measurable health benefit.”

Particulate pollution has been linked to respiratory and cardiovascular diseases, some cancers, and adverse birth outcomes, including premature birth and low infant birth weight.

The new study is part of a broader effort funded by the NASA Health and Air Quality Applied Sciences Team to use satellite data to understand how air pollution disproportionately affects underserved communities.

As the e-commerce boom of recent decades has spurred warehouse construction, pollution in nearby neighborhoods has become a growing area for research.

New structures have often sprouted on relatively inexpensive land, which tends to be home to low-income or minority populations who bear the brunt of the poor air quality, Liu said.

Another recent NASA-funded study analyzed satellite-derived nitrogen dioxide (NO2) measurements around 150,000 United States warehouses.

It found that concentrations of the gas, which is a diesel byproduct and respiratory irritant, were about 20% higher near warehouses.

Distribution Hub

For the GeoHealth paper, scientists drew on previously generated datasets of PM2.5 from 2000 to 2018 and elemental carbon, a type of PM2.5 in diesel emissions, from 2000 to 2019.

The data came from models based on satellite observations, including some from NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) instruments.

The researchers also mined a real estate database for the square footage as well as the number of loading docks and parking spaces at nearly 11,000 warehouses across portions of Los Angeles, Riverside, and San Bernardino counties, and all of Orange County.

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They found that warehouse capacity correlated with pollution. ZIP codes in the 75th percentile of warehouse square footage had 0.16 micrograms per cubic meter more PM2.5 and 0.021 micrograms per cubic meter more elemental carbon than those in the 25th percentile.

Similarly, ZIP codes in the 75th percentile of number of loading docks had 0.10 micrograms per cubic meter more PM2.5 and 0.014 micrograms per cubic meter more elemental carbon than those in the 25th percentile.

And ZIP codes in the 75th percentile of truck parking spaces had 0.21 micrograms per cubic meter more PM2.5 and 0.021 micrograms per cubic meter more elemental carbon than those in the 25th percentile.

“We found that warehouses are associated with PM2.5 and elemental carbon,” said lead author Binyu Yang, an Emory environmental health doctoral student.

Although particulate pollution fell from 2000 to 2019 due to stricter emissions standards, the concentrations in ZIP codes with warehouses remained consistently higher than for other areas.

Researchers also found that the gaps widened in the holiday shopping season, up to 4 micrograms per cubic meter — “a significant difference,” Liu said.

Satellites Provide Big Picture

Satellite observations, the researchers said, were essential because they provided a continuous map of pollution, including pockets not covered by ground-based instruments.

It’s the same motivation behind NASA’s TEMPO (Tropospheric Emissions: Monitoring of Pollution) mission, which launched in April 2023 and measures air pollution hourly during daylight over North America.

The release of TEMPO’s first maps showed higher concentrations of NO2 around cities and highways.

Meanwhile, NASA and the Italian Space Agency are collaborating to launch the MAIA (Multi-Angle Imager for Aerosols) in 2026.

It will be the first NASA satellite mission whose primary goal is to study health effects of particulate pollution while distinguishing between PM2.5 types.

“This mission will help air quality managers and policymakers conceive more targeted pollution strategies,” said Sina Hasheminassab, a co-author and science systems engineer at NASA’s Jet Propulsion Laboratory in Southern California.

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