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By NASA
NASA’s Dawn spacecraft captured this image of Vesta as it left the giant asteroid’s orbit in 2012. The framing camera was looking down at the north pole, which is in the middle of the image.NASA/JPL-Caltech/UCLA/MPS/DLR/IDA Known as flow formations, these channels could be etched on bodies that would seem inhospitable to liquid because they are exposed to the extreme vacuum conditions of space.
Pocked with craters, the surfaces of many celestial bodies in our solar system provide clear evidence of a 4.6-billion-year battering by meteoroids and other space debris. But on some worlds, including the giant asteroid Vesta that NASA’s Dawn mission explored, the surfaces also contain deep channels, or gullies, whose origins are not fully understood.
A prime hypothesis holds that they formed from dry debris flows driven by geophysical processes, such as meteoroid impacts, and changes in temperature due to Sun exposure. A recent NASA-funded study, however, provides some evidence that impacts on Vesta may have triggered a less-obvious geologic process: sudden and brief flows of water that carved gullies and deposited fans of sediment. By using lab equipment to mimic conditions on Vesta, the study, which appeared in Planetary Science Journal, detailed for the first time what the liquid could be made of and how long it would flow before freezing.
Although the existence of frozen brine deposits on Vesta is unconfirmed, scientists have previously hypothesized that meteoroid impacts could have exposed and melted ice that lay under the surface of worlds like Vesta. In that scenario, flows resulting from this process could have etched gullies and other surface features that resemble those on Earth.
To explore potential explanations for deep channels, or gullies, seen on Vesta, scientists used JPL’s Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE, to simulate conditions on the giant asteroid that would occur after meteoroids strike the surface.NASA/JPL-Caltech But how could airless worlds — celestial bodies without atmospheres and exposed to the intense vacuum of space — host liquids on the surface long enough for them to flow? Such a process would run contrary to the understanding that liquids quickly destabilize in a vacuum, changing to a gas when the pressure drops.
“Not only do impacts trigger a flow of liquid on the surface, the liquids are active long enough to create specific surface features,” said project leader and planetary scientist Jennifer Scully of NASA’s Jet Propulsion Laboratory in Southern California, where the experiments were conducted. “But for how long? Most liquids become unstable quickly on these airless bodies, where the vacuum of space is unyielding.”
The critical component turns out to be sodium chloride — table salt. The experiments found that in conditions like those on Vesta, pure water froze almost instantly, while briny liquids stayed fluid for at least an hour. “That’s long enough to form the flow-associated features identified on Vesta, which were estimated to require up to a half-hour,” said lead author Michael J. Poston of the Southwest Research Institute in San Antonio.
Launched in 2007, the Dawn spacecraft traveled to the main asteroid belt between Mars and Jupiter to orbit Vesta for 14 months and Ceres for almost four years. Before ending in 2018, the mission uncovered evidence that Ceres had been home to a subsurface reservoir of brine and may still be transferring brines from its interior to the surface. The recent research offers insights into processes on Ceres but focuses on Vesta, where ice and salts may produce briny liquid when heated by an impact, scientists said.
Re-creating Vesta
To re-create Vesta-like conditions that would occur after a meteoroid impact, the scientists relied on a test chamber at JPL called the Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE. By rapidly reducing the air pressure surrounding samples of liquid, they mimicked the environment around fluid that comes to the surface. Exposed to vacuum conditions, pure water froze instantly. But salty fluids hung around longer, continuing to flow before freezing.
The brines they experimented with were a little over an inch (a few centimeters) deep; scientists concluded the flows on Vesta that are yards to tens of yards deep would take even longer to refreeze.
The researchers were also able to re-create the “lids” of frozen material thought to form on brines. Essentially a frozen top layer, the lids stabilize the liquid beneath them, protecting it from being exposed to the vacuum of space — or, in this case the vacuum of the DUSTIE chamber — and helping the liquid flow longer before freezing again.
This phenomenon is similar to how on Earth lava flows farther in lava tubes than when exposed to cool surface temperatures. It also matches up with modeling research conducted around potential mud volcanoes on Mars and volcanoes that may have spewed icy material from volcanoes on Jupiter’s moon Europa.
“Our results contribute to a growing body of work that uses lab experiments to understand how long liquids last on a variety of worlds,” Scully said.
Find more information about NASA’s Dawn mission here:
https://science.nasa.gov/mission/dawn/
News Media Contacts
Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
818-287-4115
gretchen.p.mccartney@jpl.nasa.gov
Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
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Last Updated Dec 20, 2024 Related Terms
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By NASA
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NASA’s X-59 quiet supersonic research aircraft completed its first maximum afterburner test at Lockheed Martin’s Skunk Works facility in Palmdale, California. This full-power test, during which the engine generates additional thrust, validates the additional power needed for meeting the testing conditions of the aircraft. The X-59 is the centerpiece of NASA’s Quesst mission, which aims to overcome a major barrier to supersonic flight over land by reducing the noise of sonic booms.Lockheed Martin Corporation/Garry Tice NASA completed the first maximum afterburner engine run test on its X-59 quiet supersonic research aircraft on Dec. 12. The ground test, conducted at Lockheed Martin’s Skunk Works facility in Palmdale, California, marks a significant milestone as the X-59 team progresses toward flight.
An afterburner is a component of some jet engines that generates additional thrust. Running the engine, an F414-GE-100, with afterburner will allow the X-59 to meet its supersonic speed requirements. The test demonstrated the engine’s ability to operate within temperature limits and with adequate airflow for flight. It also showed the engine’s ability to operate in sync with the aircraft’s other subsystems.
The X-59 is the centerpiece of NASA’s Quesst mission, which seeks to solve one of the major barriers to supersonic flight over land by making sonic booms quieter. The X-59’s first flight is expected to occur in 2025.
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Last Updated Dec 20, 2024 EditorDede DiniusContactMatt Kamletmatthew.r.kamlet@nasa.gov Related Terms
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By NASA
This article is for students grades 5-8.
The Sun is the star of our solar system. Its gravity holds Earth and our planetary neighbors in its orbit. At 865,000 miles (1.4 million km) in diameter, it’s the largest object in our solar system. On Earth, its influence is felt in our weather, seasons, climate, and more. Let’s learn about our dynamic star and its connections to life on Earth.
What is the Sun, and what is it made of?
The Sun is a yellow dwarf star. It is approximately 4.5 billion years old and is in its “main sequence” phase. This means it is partway through its lifecycle with a few billion more years ahead of it.
The Sun is made of hydrogen and helium gases. At its core, hydrogen is fused to form helium. This nuclear reaction creates the Sun’s heat and light. That energy moves outward through the Sun’s radiative zone and convective zone. It then reaches the Sun’s visible surface and lower atmosphere, called the photosphere. Above the photosphere lies the chromosphere, which forms the Sun’s middle atmosphere, and beyond that is the corona, the Sun’s outermost atmosphere.
The Sun is a yellow dwarf star with a complex series of layers and features.NASA What is the solar cycle?
The Sun goes through a pattern of magnetic activity known as the solar cycle. During each cycle, the Sun experiences a very active period called “solar maximum” and a less active period called “solar minimum.”
During solar maximum, increased magnetic activity creates sunspots. These appear as darker, cooler spots on the Sun’s surface. The more sunspots we can see, the more active the Sun is.
The solar cycle begins at solar minimum, peaks at solar maximum, and then returns to solar minimum. This cycle is driven by the Sun’s magnetic polarity, which flips – north becomes south, and vice versa – every 11 years. It takes two cycles – or 22 years – to complete the full magnetic cycle where the poles return to their original positions.
The Sun’s level of magnetic activity changes throughout its 11-year solar cycle. During each cycle, the Sun experiences a less-active period called “solar minimum” (left) and a very active period called “solar maximum” (right).NASA Wait. The Sun’s magnetic poles can flip??
Yes! Like Earth, the Sun has north and south magnetic poles. But unlike Earth, the Sun’s poles flip regularly. Each 11-year solar cycle is marked by the flipping of the Sun’s poles. The increased magnetic activity during solar maximum makes the north and south poles less defined. As the cycle moves back to solar minimum, the polarization of the poles returns – with flipped polarity.
Unlike Earth, the Sun’s poles regularly flip with each 11-year solar cycle.NASA What is space weather?
Space weather includes phenomena such as solar wind, solar storms, and solar flares. When space weather conditions are calm, there may be little noticeable effect on Earth. But when the Sun is more active, space weather has real impacts on Earth and in space.
Let’s explore these phenomena and how they affect our planet.
Periods of increased solar activity can cause noticeable effects on Earth and in space.NASA What is solar wind?
Solar wind is a stream of charged particles that flow outward from the Sun’s corona. It extends far beyond the orbit of the planets in our solar system. When solar wind reaches Earth, its charged particles interact with Earth’s magnetic field. This causes colorful streams of moving light at Earth’s north and south poles called aurora.
Earth’s magnetic field protects our planet from the charged solar particles of the solar wind.NASA What are solar storms, solar flares, and coronal mass ejections?
The Sun’s magnetic fields are a tangle of constant motion. These fields twist and stretch to the point that they snap and reconnect. When this magnetic reconnection occurs, it releases a burst of energy that can cause a solar storm.
Solar storms can include phenomena such as solar flares or coronal mass ejections. They happen more frequently around the solar maximum of the Sun’s cycle. A solar flare is an intense burst of light and energy from the Sun’s surface. Solar flares tend to happen near sunspots where the Sun’s magnetic fields are strongest. A coronal mass ejection is a massive cloud of material flowing outward from the Sun. These can occur on their own or along with solar flares.
The Sun’s magnetic field is strongest near sunspots. These active regions of the Sun’s surface release energy in the form of solar flares and coronal mass ejections like these.NASA How do these phenomena affect Earth?
When a solar storm erupts towards Earth, our atmosphere and magnetic field protect us from significant harm. However, some impacts are possible, both on Earth and in space. For example, strong solar storms can cause power outages and radio blackouts. GPS signals can be disrupted. Satellite electronics can be affected. And astronauts working outside of the International Space Station could be exposed to dangerous radiation. NASA monitors and forecasts space weather to protect the safety and health of astronauts and spacecraft.
When charged particles from intense solar storms interact with Earth’s magnetic fields, colorful auroras like this one captured in Saskatchewan, Canada, can occur.NASA Learn more about the Sun
NASA’s Parker Solar Probe launched in 2018 on the first-ever mission to fly into the Sun’s corona. Since its first pass through the corona in 2021, every orbit has brought it closer to the Sun. On Dec. 24, 2024, it makes the first of its three final, closest solar approaches of its primary mission. Test your knowledge with NASA’s new quiz, Kahoot! Parker Solar Probe trivia.
Visit these resources for more details about the Sun:
https://science.nasa.gov/sun/facts/ https://spaceplace.nasa.gov/all-about-the-sun/en/ https://science.nasa.gov/exoplanets/stars/ Explore More For Students Grades 5-8 View the full article
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