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NASAâs Webb Investigates Eternal Sunrises, Sunsets on Distant World
JUL 15, 2024
Researchers using NASAâs James Webb Space Telescope have finally confirmed what models have previously predicted: An exoplanet has differences between its eternal morning and eternal evening atmosphere.
WASP-39 b, a giant planet with a diameter 1.3 times greater than Jupiter, but similar mass to Saturn that orbits a star about 700 light-years away from Earth, is tidally locked to its parent star.
This means it has a constant dayside and a constant nightsideâone side of the planet is always exposed to its star, while the other is always shrouded in darkness.
Using Webbâs NIRSpec (Near-Infrared Spectrograph), astronomers confirmed a temperature difference between the eternal morning and eternal evening on WASP-39 b, with the evening appearing hotter by roughly 300 Fahrenheit degrees (about 200 Celsius degrees).
They also found evidence for different cloud cover, with the forever morning portion of the planet being likely cloudier than the evening.
Astronomers analyzed the 2- to 5-micron transmission spectrum of WASP-39 b, a technique that studies the exoplanetâs terminator, the boundary that separates the planetâs dayside and nightside.
A transmission spectrum is made by comparing starlight filtered through a planetâs atmosphere as it moves in front of the star, to the unfiltered starlight detected when the planet is beside the star.
When making that comparison, researchers can get information about the temperature, composition, and other properties of the planetâs atmosphere.
âWASP-39 b has become a sort of benchmark planet in studying the atmosphere of exoplanets with Webb,â said NĂŠstor Espinoza, an exoplanet researcher at the Space Telescope Science Institute and lead author on the study.
âIt has an inflated, puffy atmosphere, so the signal coming from starlight filtered through the planetâs atmosphere is quite strong.â
Previously published Webb spectra of WASP-39bâs atmosphere, which revealed the presence of carbon dioxide, sulfur dioxide, water vapor, and sodium, represent the entire day/night boundary â there was no detailed attempt to differentiate between one side and the other.
Now, the new analysis builds two different spectra from the terminator region, essentially splitting the day/night boundary into two semicircles, one from the evening, and the other from the morning.
Data reveals the evening as significantly hotter, a searing 1,450 degrees Fahrenheit (800 degrees Celsius), and the morning a relatively cooler 1,150 degrees Fahrenheit (600 degrees Celsius).
âItâs really stunning that we are able to parse this small difference out, and itâs only possible due Webbâs sensitivity across near-infrared wavelengths and its extremely stable photometric sensors,â said Espinoza.
âAny tiny movement in the instrument or with the observatory while collecting data would have severely limited our ability to make this detection. It must be extraordinarily precise, and Webb is just that.â
Extensive modeling of the data obtained also allows researchers to investigate the structure of WASP-39 bâs atmosphere, the cloud cover, and why the evening is hotter.
While future work by the team will study how the cloud cover may affect temperature, and vice versa, astronomers confirmed gas circulation around the planet as the main culprit of the temperature difference on WASP-39 b.
On a highly irradiated exoplanet like WASP-39 b that orbits relatively close to its star, researchers generally expect the gas to be moving as the planet rotates around its star:
Hotter gas from the dayside should move through the evening to the nightside via a powerful equatorial jet stream. Since the temperature difference is so extreme, the air pressure difference would also be significant, which in turn would cause high wind speeds.
Using General Circulation Models, 3-dimensional models similar to the ones used to predict weather patterns on Earth, researchers found that on WASP-39 b the prevailing winds are likely moving from the night side across the morning terminator, around the dayside, across the evening terminator and then around the nightside.
As a result, the morning side of the terminator is cooler than the evening side. In other words, the morning side gets slammed with winds of air that have been cooled on the nightside, while the evening is hit by winds of air heated on the dayside.
Research suggests the wind speeds on WASP-39 b can reach thousands of miles an hour!
âThis analysis is also particularly interesting because youâre getting 3D information on the planet that you werenât getting before,â added Espinoza.
https://science.nasa.gov/missions/webb/nasas-webb-investigates-eternal-sunrises-sunsets-on-distant-world/
https://www.nature.com/articles/s41586-024-07768-4
Scientist discover tunnels on the Moon - and NASA could send humans in to investigate
UPDATED: 09:13, Tue, Jul 16, 2024
Scientists have discovered a cave on the Moon for the first time. The cave is at least 100m deep.
It could be an ideal place for humans to build a permanent base, according to research published in the scientific journal Nature Astronomy.
It is just one in probably hundreds of caves hidden in an âunderground, undiscovered world,â researchers told the BBC.
Countries are racing to establish a permanent human presence on the Moon, but obstacles such as radiation, extreme temperatures, and space weather remain in the picture, providing complications.
Helen Sharman, the first British astronaut to travel to space, told BBC News that the newly discovered cave looked like a good place for a base and suggested humans could live in lunar pits in 20-30 years.
However, Sharman said this cave is so deep that astronauts might need âjet packs or a liftâ to get out.
Lorenzo Bruzzone and Leonardo Carrer at the University of Trento in Italy found the cave using radar that examined a rocky plain called the Mare Tranquillitatis.
"âŚWhen you make these discoveries, and you look at these images, you realize youâre the first person in the history of humanity to see it,â Professor Carrer said to BBC.
âAfter all, life on Earth began in caves, so it makes sense that humans could live inside them on the Moon,â Carrer added.
Once Professor Bruzzone and Professor Carrer understood how big the cave was, they realized it could be a good spot for a lunar base.
The Moon cave could benefit humans, and scientists are also investigating how it could help answer fundamental questions about the history of the Moon and our solar system.
The rocks inside the cave will not be as damaged or eroded by space weather so they can provide an extensive geological record dating back billions of years.
Although the cave has not been fully explored, researchers are hopeful that ground-penetrating radar, cameras, or even robots can be used to map it.
https://www.express.co.uk/news/science/1923698/scientist-discovered-cave-on-moon
'What exactly is a planet?' Astronomers want to amend the definition
July 15, 2024
Three astronomers last week proposed expanding the official definition of a planet to encompass worlds orbiting stars other than our own, a nuance not currently included in the formal definition of the term established in 2006 by the International Astronomical Union, or IAU.
If the trio's new definition pans out, thousands of celestial bodies across the universe could be confirmed as formal planets.
For a celestial body to qualify as a planet per the current IAU definition, it must orbit the sun, should have cleared the area around its orbit, and must have enough mass that its gravity would have sculpted it into a nearly round shape in order to be a "planet."
The third requirement is particularly vague because it does not quantify just how round the celestial body should be, according to a team led by astronomer Jean-Luc Margot of the University of California in Los Angeles (UCLA).
"The Earth isn't completely round, so how round does a planet have to be?" study co-author Brett Gladman, who is an astronomy professor at the University of British Columbia said in a recent statement.
"If you look at a world orbiting another star, with current technology, we can't measure the shape."
Three astronomers last week proposed expanding the official definition of a planet to encompass worlds orbiting stars other than our own, a nuance not currently included in the formal definition of the term established in 2006 by the International Astronomical Union, or IAU. If the trio's new definition pans out, thousands of celestial bodies across the universe could be confirmed as formal planets.
For a celestial body to qualify as a planet per the current IAU definition, it must orbit the sun, should have cleared the area around its orbit, and must have enough mass that its gravity would have sculpted it into a nearly round shape in order to be a "planet." The third requirement is particularly vague because it does not quantify just how round the celestial body should be, according to a team led by astronomer Jean-Luc Margot of the University of California in Los Angeles (UCLA).
"The Earth isn't completely round, so how round does a planet have to be?" study co-author Brett Gladman, who is an astronomy professor at the University of British Columbia said in a recent statement.
"If you look at a world orbiting another star, with current technology, we can't measure the shape."
The researchers also say some aspects of the current definition are too specific, such as the one that requires planets must orbit our sun, because it excludes thousands of worlds around other stars in the universe that otherwise meet the criteria to be called a planet.
"We now know of thousands of 'planets' orbiting other stars, but the IAU definition applies only to those in our solar system, which is obviously a big flaw," said Margot.
"We propose a new definition that can be applied to celestial bodies that orbit any star, stellar remnant, or brown dwarf."
In a paper posted to a preprint server on July 10, which is soon to be published in the Planetary Science Journal, Margot and his colleagues propose determining planetary status of a celestial object based on its mass.
Per the proposed definition, a world could be called a planet if it is within certain mass limits. For instance, it must be lighter than 13 Jupiters, beyond which nuclear fusion begins and the object is no longer a planet but rather a substar called a brown dwarf.
"Having definitions anchored to the most easily measurable quantity â mass â removes arguments about whether or not a specific object meets the criterion," said Gladman. "This is a weakness of the current definition."
Pluto, which in 2006 was demoted to a dwarf planet in a highly-debated decision by the IAU, would be lighter than the lowest limit suggested by the newly proposed definition, and would thus continue to remain a dwarf planet.
Additionally, the current IAU definition requiring planets to have "nearly round" shapes is difficult to implement, Margot and his team argue, and thus is effectively useless as shapes of many faraway worlds cannot be resolved with certainty.
Instead, using thresholds based on mass would "replace a vague and impractical prescription regarding roundness," the researchers write in the new paper.
"We're drawing a line in the sand by putting some numbers to these definitions, to encourage our community to start the discussion: What exactly is a planet?" said Gladman.
The IAU has so far made no announcements about possible changes to its official definition of a planet.
The UCLA statement noted that Margot is scheduled to present the proposed definition next month at the IAU General Assembly in Cape Town, South Africa.
https://www.space.com/planet-definition-amendment-exoplanets
SpaceX test-fires Super Heavy Starship booster ahead of 5th flight
July 16, 2024
Super Heavy is breathing fire once again.
SpaceX ignited the engines on its Super Heavy booster yesterday (July 15), ahead of Starship's next integrated flight test (IFT), expected in the next few weeks.
IFT-5 will be fifth launch of Starship's fully-stacked vehicle, and its most ambitious to date.
The spacecraft has been contracted by NASA as the lunar lander for its Artemis 3 mission, and has also been touted by SpaceX CEO Elon Musk as eventually being capable of flying humans to Mars.
The 233 foot (71 meter) booster was rolled to the launchapd at SpaceX's test site on July 9, ahead of yeaterday's full-duration "static test fire," at the company's Starbase facility, in Texas.
With Super Heavy secured to launchpad, the rocket's 33 Raptor engines fire at full thrust for about 20 seconds in video captured and shared by SpaceX in a post on X.
Full duration static fire of Flight 5 Super Heavy booster pic.twitter.com/8rF9KUdMUDJuly 15, 2024
Each of Starship's four test flights has gone farther and accomplished more than its predecessor, with the rocket's the most recent launch in June being hailed as a complete success.
That launch saw Starship and its Super Heavy booster both return, as planned, for controlled ocean splashdowns. Now, hoping to build on that success, SpaceX will attempt to reach even further on Starship's fifth flight.
Starship is designed to as a completely reusable system. Like the first-stage of SpaceX's Falcon 9 booster, Super Heavy is designed with grid fins to help control its reentry through the atmosphere, but unlike the current workhorse of SpaceX's fleet, when Super Heavy returns to land, the plan is for it to fly straight back to the pad where it launched.
The Starship launch tower features two massive "chopstick" arms that are designed to catch Super Heavy by its grid fins, as the booster arrests its momentum to a momentary standstill in midair to sucumb to the chopsticks' tender embrace.
This way, in the efforts of rapid refurbishment, the booster is already where it needs to be in order to launch again.
During its fourth flight, though Super Heavy's landing burn over the ocean was nowhere near its launchpad in Starbase, Texas, SpaceX closed the launch tower's chopstick arms in conjunction with the booster's water landing, seemingly to test the system's timing and capabilities.
Now, they're going to try it for real. Following the success of IFT-4, Musk wrote in a post on X, "aiming to try this in late July!" in response to a video featuring an animated Super Heavy booster catch.
As for when the next Starship launch will take place, on July 5, Musk said "four weeks," in a post on X.
That timeline would put the launch around Aug. 2, however the rocket billionaire's estimates are often optimistically hopefull.
So, at the earliest, we may see Starship IFT-5 liftoff around the beginning of August.
https://www.space.com/spacex-starship-super-heavy-test-fire-booster-5th-flight
U.S. nuclear command satellites need hardening against attacks, report warns
July 15, 2024
The United States should harden its low Earth orbit satellites that support nuclear command and control against radiation effects from potential high-altitude nuclear detonations, according to a new report from a prominent think tank.
The Atlantic Councilâs Scowcroft Center for Strategy and Security released a study July 15 titled âModernizing Space-Based Nuclear Command, Control, and Communicationsâ that recommends steps to protect space-based elements of the U.S. nuclear command, control and communications (NC3) system.
The report comes amid growing concerns about Russiaâs development of space-based nuclear weapons and the vulnerability of critical military satellites.
NC3 comprises the sensors, communications networks, and command centers that allow the President to direct nuclear forces.
Its space segment includes satellites for missile warning, secure communications, and nuclear detonation detection.
âIn a most disturbing scenario, the efficacy of commercial LEO satellites in supporting Ukraine could lead the Russians (or the Chinese in a Taiwan invasion, for instance) to assess that the greatest military effectiveness from the limited use of nuclear weapons would be to detonate just one in LEO,â the report stated.
A high-altitude nuclear blast could create widespread electromagnetic pulse effects and inject high-energy particles into Earthâs radiation belts, potentially crippling unprotected satellites, the authors warned.
Low Earth orbit satellites between 160-2,000 km altitude are especially at risk due to their proximity.
âA high-altitude nuclear detonation would raise the peak radiation flux in parts of the Van Allen radiation belts by three to four orders of magnitude, cause the failure in weeks to months of most if not all LEO satellites not specifically hardened against this threat,â according to the report.
U.S. modernizing nuclear command technology
The U.S. is currently modernizing its aging NC3 infrastructure as part of a broader nuclear forces upgrade.
Key space assets include the Space-Based Infrared System for missile warning and the Advanced Extremely High Frequency satellites for assured communications.
However, a planned shift to smaller, distributed satellite constellations in low Earth orbit creates new vulnerabilities that must be addressed, the report said.
The Space Forceâs Space Development Agency is deploying hundreds of satellites for missile tracking and other military purposes.
âThe ability of space-based NC3 systems to ensure ânuclear suretyâ â the absolute reliability and security of nuclear operations â is being challenged,â the Atlantic Council report stated.
âThis is because these systems may become vulnerable to attack or interference from advanced counterspace weapons.â
The authors recommend accelerating deployment of radiation-hardened satellites and other protective measures for next-generation NC3 systems.
The report highlights how the emergence of multiple nuclear peers has complicated the strategic landscape.
It argues that Chinaâs nuclear buildup and views on strategic stability, coupled with the possibility of limited nuclear use, are raising questions about the adequacy of existing and planned NC3 capabilities.
On the technical front, the development of sophisticated anti-satellite weapons by Russia and China poses a direct threat to U.S. space-based NC3 assets, the study found.
The transition from analog to digital systems also introduces new cyber vulnerabilities that must be addressed.
As the Pentagon shifts to more distributed satellite architectures, the report warns that nuclear surety requirements may get overlooked amid competing priorities.
It calls for ensuring these critical capabilities remain a top focus in future space systems planning.
https://spacenews.com/u-s-nuclear-command-satellites-need-hardening-against-attacks-report-warns/
https://www.atlanticcouncil.org/in-depth-research-reports/issue-brief/modernizing-space-based-nuclear-command-control-and-communications/