NASA Astronomy Picture of the Day

September 9, 2024

Mars: Moon, Craters, and Volcanos

If you could fly over Mars, what might you see? The featured image shows exactly this in the form of a Mars Express vista captured over a particularly interesting region on Mars in July. The picture's most famous feature is Olympus Mons, the largest volcano in the Solar System, visible on the upper right. Another large Martian volcano is visible on the right horizon: Pavonis Mons. Several circular impact craters can be seen on the surface of the aptly named red planet. Impressively, this image was timed to capture the dark and doomed Martian moon Phobos, visible just left of center. The surface feature on the lower left, known as Orcus Patera, is unusual for its large size and oblong shape, and mysterious because the processes that created it still remain unknown. ESA's robotic Mars Express spacecraft was launched in 2003 and, among many notable science discoveries, bolstered evidence that Mars was once home to large bodies of water.

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

Goodnight, Cluster: brilliant end to trailblazing mission

09/09/2024

The first satellite in ESA’s Cluster quartet safely came back down to Earth last night in a world-first ‘targeted reentry’, marking a brilliant end to this remarkable mission.

The spacecraft, dubbed ‘Salsa’ (Cluster 2), reentered Earth’s atmosphere at 20:47 CEST on 8 September 2024 over the South Pacific Ocean. In this region, any risk of fragments reaching land are absolutely minimised.

During the last two decades Cluster has spent in space, it has provided invaluable data on how the Sun interacts with Earth’s magnetic field, helping us better understand and forecast space weather.

With this first-ever targeted reentry, Cluster will go down in history for a second reason – helping ESA become a world-leader in sustainable space exploration.

The reentry follows a tweaking of Salsa’s orbit back in January 2024 to target a region as far as possible from populated regions. This ensured that any spacecraft parts that survive the reentry would fall over the open ocean.

Over the past days, weeks and months, ESA’s spacecraft operators kept a close eye on Salsa as it came closer to Earth, slightly adjusting the spacecraft’s trajectory just once to keep it on track.

Nowadays, satellite missions are designed according to regulations that require them to minimise the risk of causing damage on their return to Earth.

However, when Cluster was built back in the 1990s no such regulations were in place. Without intervention, the four Cluster satellites would have reentered Earth’s atmosphere naturally – but with less control over when or where this would happen.

ESA Director of Operations, Rolf Densing explains why ESA decided to end the mission in this way: “Salsa’s reentry was always going to be very low risk, but we wanted to push the boundaries and reduce the threat even further, demonstrating our commitment to ESA’s Zero Debris approach.”

“By studying how and when Salsa and the other three Cluster satellites burn up in the atmosphere, we are learning a great deal about reentry science, hopefully allowing us to apply the same approach to other satellites when they come to the end of their lives.”

Salsa’s reentry marks the end of a unique mission that will ultimately help protect humanity from our tempestuous Sun.

Water? Warmth? Minerals? All vital for life, but not unique to planet Earth. Perhaps the one key thing that makes Earth a remarkable habitable world where life can thrive is its powerful magnetosphere.

Just a few hundred kilometres above our heads, a continuous battle is being fought between the forces of nature. Like a ship in a never-ending storm, Earth is bombarded by swarms of particles ejected from the Sun at supersonic speeds.

Most of these solar wind particles are deflected by the magnetosphere, and sail harmlessly by. But Earth’s shield is not bulletproof.

Gusts of solar wind can squeeze it mercilessly, pushing energetic particles through weak spots, and potentially damaging electronic equipment including vital satellites orbiting in space.

It might sound like science fiction, but scientists have been studying this continuous feud between the Sun and Earth for many years, first from the ground and then with the aid of single satellites.

But the complexities of the Sun-Earth connection have always eluded them. Until Cluster came along.

Director of Science Prof. Carole Mundell says: “Cluster is the first mission to make detailed studies, models and 3D maps of Earth’s magnetic field, as well as related processes within and around it.

We’re proud to say that through Cluster and other missions, ESA has advanced humankind’s understanding of how the solar wind interacts with the magnetosphere, helping us prepare for the dangers it can bring.”

Our understanding of space weather – the environmental conditions in space caused by the Sun’s activity – depends on understanding many different factors: the behaviour of the Sun, how the solar wind travels through space, and how Earth’s magnetosphere responds.

With Cluster, ESA took on the challenge of uncovering how Earth’s magnetosphere responds to the solar wind.

Other ESA missions have studied different parts of the process, with Solar Orbiter, SOHO, Proba-2 and Ulysses keeping watching on the Sun itself, and Swarm and Double Star also studying Earth’s magnetic environment.

Double Star focused on the ‘magnetotail’ that stretches away from planet Earth, and Swarm continues to analyse Earth’s magnetic field itself.

1/2

>>21557499

Cluster’s scientific torch will be passed on to the ESA/Chinese Academy of Sciences Solar wind Magnetosphere Ionosphere Link Explorer (Smile) mission, set to launch in late 2025.

A few years later, ESA’s Vigil mission will head into space to put the different puzzle pieces together, aiming to provide continuous, near real-time data on potentially hazardous solar activity. Ultimately this will help us ensure safe satellite communications and space and air travel.

While most missions exploring Earth’s magnetic phenomena focus on the equator, the Cluster quartet circled over the poles, where there is a lot of magnetic activity. Solar wind in this area can dive deeper into Earth’s upper atmosphere, giving rise to the spectacular auroras.

Cluster’s ability to observe higher latitudes than other missions meant that it revealed parts of the magnetosphere that we’ve never been able to ‘see’ before with multiple spacecraft at the same time.

Through its mapping of Earth’s magnetic field, and comparison of this to Mars’s lacklustre present-day magnetism, Cluster has reaffirmed the importance of our magnetosphere in shielding us from the solar wind.

The mission also helped us understand weaknesses in the magnetosphere, including how solar wind particles can break through the shield. It even discovered the origin of ‘killer electrons’, energetic particles in the outer belt of radiation surrounding Earth, that can cause havoc for satellites.

By continually monitoring and recording the dynamics and properties of Earth’s magnetosphere over two decades, Cluster has amassed an unprecedented wealth of data, allowing scientists to make truly ground-breaking findings, including on longer-term trends.

After an incredibly successful 24 years in space, ESA took the decision to deorbit the four Cluster satellites throughout 2024–2026. Planning the reentries at this time made it possible for the Cluster spacecraft to contribute to reentry science as a final farewell.

“Cluster’s multi-spacecraft design has always been key to its success,” explains Philippe Escoubet, Cluster Mission Manager.

“By using four spacecraft instead of one, Cluster was able to uniquely measure multiple areas of space simultaneously.

When closer together, the Cluster spacecraft could dig into the finer magnetic structures in near-Earth space. When further apart, they could obtain a broader view of wider-scale activity.”

And now ESA is using the fact that there are four Cluster satellites to better understand how reentries work.

By comparing the reentries of four identical satellites under different space weather conditions and with slightly different trajectories, ESA’s space debris team is conducting a valuable experiment on the break-up of satellites in the atmosphere.

Ultimately, this will make satellite reentries even safer.

Although Cluster has become an enormous scientific success, its early days didn’t go off without a hitch.

The rocket used to launch the Rumba (Cluster 1) and Tango (Cluster 4) satellites in 2000 left them in an incorrect orbit, forcing them to rely on their own propulsion, as well as the upper stage of the rocket, to get to the right position to join Salsa (Cluster 2) and Samba (Cluster 3).

The mishap followed the failed launch of the original Cluster quartet in 1996.

Since then, the mission has made tremendous progress, far outlasting its original planned lifetime and contributing enormously to our understanding of the interaction between the Sun and Earth.

And yesterday, Cluster became a key piece in ESA’s efforts towards more sustainable space exploration.

https://www.esa.int/Science_Exploration/Space_Science/Cluster/Goodnight_Cluster_brilliant_end_to_trailblazing_mission

2/2

https://www.livescience.com/space/astronomy/the-james-webb-telescope-found-hundreds-of-little-red-dots-in-the-ancient-universe-we-still-don-t-know-what-they-are

The James Webb telescope found hundreds of 'little red dots' in the ancient universe. We still don't know what they are.

September 8, 2024

Astronomers exploring the faraway universe with the James Webb Space Telescope, NASA's most powerful telescope, have found a class of galaxies that challenges even the most skillful creatures in mimicry — like the mimic octopus.

This creature can impersonate other marine animals to avoid predators. Need to be a flatfish? No problem. A sea snake? Easy.

When astronomers analyzed the first Webb images of the remote parts of the universe, they spotted a never-before-seen group of galaxies.

These galaxies — some hundreds of them and called the Little Red Dots — are very red and compact, and visible only during about 1 billion years of cosmic history.

Like the mimic octopus, the Little Red Dots puzzle astronomers, because they look like different astrophysical objects.

They're either massively heavy galaxies or modestly sized ones, each containing a supermassive black hole at its core.

However, one thing is certain. The typical Little Red Dot is small, with a radius of only 2% of that of the Milky Way galaxy. Some are even smaller.

As an astrophysicist who studies faraway galaxies and black holes, I am interested in understanding the nature of these little galaxies. What powers their light and what are they, really?

Astronomers analyze the light our telescopes receive from faraway galaxies to assess their physical properties, such as the number of stars they contain.

We can use the properties of their light to study the Little Red Dots and figure out whether they're made up of lots of stars or whether they have a black hole inside them.

Light that reaches our telescopes ranges in wavelength from long radio waves to energetic gamma rays.

Astronomers break the light down into the different frequencies and visualize them with a chart, called a spectrum.

Sometimes, the spectrum contains emission lines, which are ranges of frequencies where more intense light emission occurs.

In this case, we can use the spectrum's shape to predict whether the galaxy is harboring a supermassive black hole and estimate its mass.

Similarly, studying X-ray emisson from the galaxy can reveal a supermassive black hole's presence.

As the ultimate masters of disguise, the Little Red Dots appear as different astrophysical objects, depending on whether astronomers choose to study them using X-rays, emission lines or something else.

The information astronomers have collected so far from the Little Red Dots' spectra and emission lines has led to two diverging models explaining their nature.

These objects are either extremely dense galaxies containing billions of stars or they host a supermassive black hole.

In the stars-only hypothesis, the Little Red Dots contain massive amounts of stars — up to 100 billion stars. That's approximately the same number of stars as in the Milky Way — a much larger galaxy.

1/2

>>21557552

Imagine standing alone in a huge, empty room. This vast, quiet space represents the region of the universe in the vicinity of our solar system where stars are sparsely scattered. Now, picture that same room, but packed with the entire population of China.

This packed room is what the core of the densest Little Red Dots would feel like. These astrophysical objects may be the densest stellar environments in the entire universe. Astronomers aren't even sure whether such stellar systems can physically exist.

Then, there is the black hole hypothesis. The majority of Little Red Dots display clear signs of the presence of a supermassive black hole in their center.

Astronomers can tell whether there's a black hole in the galaxy by looking at large emission lines in their spectra, created by gas around the black hole swirling at high speed.

Astronomers actually estimate these black holes are too massive, compared with the size of their compact host galaxies.

Black holes typically have a mass of about 0.1% of the stellar mass of their host galaxies. But some of these Little Red Dots harbor a black hole almost as massive as their entire galaxy.

Astronomers call these overmassive black holes, because their existence defies the conventional ratio typically observed in galaxies.

There's another catch, though. Unlike ordinary black holes, those presumably present in the Little Red Dots don't show any sign of X-ray emission.

Even in the deepest, high-energy images available, where astronomers should be able to easily observe these black holes, there's no trace of them.

Using the Webb telescope and more powerful X-ray telescopes to take additional observations will eventually uncover a feature that astronomers can attribute to only one of the two scenarios.

For example, if astronomers clearly detected X-ray or radio emission, or infrared light emitted from around where the black hole might be, they'd know the black hole hypothesis is the right one.

Just like how our marine friend can pretend to be a starfish, eventually it will move its tentacles and reveal its true nature.

2/2

Mind-blowing thing happened after man used balloon to launch GoPro into space

Updated 15:08 9 Sep 2024 GMT+1

People really love sticking GoPros all over the place, don't they?

There are quite a few folks who've developed a hobby of dropping them into the sea and showing people what aquatic creatures lurk beneath the waves.

Possibly the worst use of a GoPro I've ever witnessed was at a football game where the bloke in front of me was holding it in one hand to record the game while his other hand clutched his phone filming the same thing.

He'd alternate them depending on how tired his arms were, resulting in two terrible recording attempts while keeping the ways he was blocking my view fresh.

That might be the worst way I've ever seen someone use a GoPro, but sending one of the little cameras as close to space as a balloon could carry it might just be one of the best.

YouTuber BloonStu used a balloon to float a GoPro up as high as it'd go until it got a damn good view of space.

Launching his balloon from Texas, the GoPro floated up above the clouds until they were naught but tiny features drifting below.

Up and up the GoPro flew until the camera stopped seeing the ground and started seeing the Earth.

The camera could capture the curvature of the planet as it looked down at one tiny aspect of this massive ball that we all live on, except perhaps for those astronauts who are stuck in space for the foreseeable future.

The balloon with a GoPro rose ever higher until the inevitable happened, it burst.

What had seconds earlier been soaring above the world was now tumbling back down to the ground, and even though a parachute was deployed the air pressure and density this close to space was so thin that it had little impact.

Fortunately the parachute became of more use the closer to the ground the GoPro got, and the camera came down to land in a field.

The YouTuber was able to follow a tracking device and locate his gizmo.

He did note that he followed all Federal Aviation Administration regulations and notified the Flight Standards District Office of his launch beforehand.

The man added: "A NOTAM [Notice to Air Missions] was even filed with Ft Worth center for balloon activity."

As for why he did this, he explained in his video: "Mostly, I had free time and needed a project/hobby to keep me engaged and secondly, space is neat."

Space is indeed neat, and if you have a balloon that can fly a camera close to it and have a good look before bursting (which handily returns the camera to you) then what's stopping you?

https://www.ladbible.com/community/weird/balloon-launch-gopro-space-happened-064824-20240909

https://www.youtube.com/watch?v=3y0nHhFGXDo

SpaceX to launch private Polaris Dawn spacewalk mission overnight on farthest human spaceflight since Apollo

September 9, 2024

SpaceX is about to launch four private astronauts farther than any human has flown since the end of the Apollo era.

The crew will be on a mission to perform history's first commercial spacewalk.

The mission, Polaris Dawn, will liftoff early Tuesday (Sept. 10) during a four-hour launch window that opens at at 3:38 a.m. ET (0738 GMT).

Two additional launch opportunities are available within the four-hour window; one at 5:23 a.m. ET (0923 GMT) and another at 7:09 a.m. ET (1109 GMT).

Backup launch opportunities are available on Wednesday (Sept. 11) at the same times, according to SpaceX.

"Targeting no earlier than Tuesday, Sept. 10 for Falcon 9's launch of the Polaris Dawn mission," SpaceX wrote in a post on X (formerly Twitter) on Sept. 8.

"Weather is currently 40% favorable for liftoff, and conditions at the possible splashdown sites for Dragon's return to Earth remain a watch item."

To watch the launch live, you can tune into Space.com or SpaceX's webcast on X, starting about 3.5 hours before liftoff.

Polaris Dawn will liftoff from SpaceX's Launch Complex-39A at NASA's Kennedy Space Center — the same pad that supported all the crewed Apollo missions to the moon.

Though it's true each of SpaceX's astronaut launches to date has flown out of LC-39A, it's particularly fitting that the members of Polaris Dawn will also launch from there, as this mission will take them further than any crewed flight has gone since Apollo 17, in 1972.

Billionaire philanthropist Jared Isaacman is footing the bill for the mission, and intends it to be the first of three in his "Polaris Program."

Dawn will be the second space mission Isaacman has funded, as well as his second personal launch to orbit. His first in both cases came in 2021, with the launch of Inspriation4 — the first all-civilian spaceflight.

These missions, and the next two planned for the Polaris Program, are being flown with the dual goal of furthering the bounds of private human space exploration and raising money to support St. Jude Children's Research Hospital.

With Inspriation4, Isaacman and the mission were able to raise $250 million in donations for the organization.

1/2

>>21557733

Isaacman will fly as Polaris Dawn's mission commander, and will be joined by the mission's pilot, retired United States Air Force (USAF) Lieutenant Colonel Scott "Kidd" Poteet, and the first two SpaceX employees to launch to orbit, Sarah Gillis and Anna Menon, who both work as Lead Space Operations Engineers. Gillis and Menon will serve as mission specialists.

The crewmembers will launch aboard a SpaceX Crew Dragon capsule into an elliptical orbit, flying to an initial maximum altitude (apogee) of about 745 miles (1,200 kilometers), where they will spend the beginning of their first day in space.

After several orbits, Dragon will raise its apogee about 125 miles, to a maximum altitude of 870 miles (1,400 kilometers).

At this distance from Earth, Polaris Dawn will fly through a portion of the radiation belts wrapped around our planet beyond its lower orbits.

Taking advantage of this course, the crew plans to complete a number of science experiments to study the deep-space radiation environment.

The trajectory also reaches another significant milestone for human spaceflight. Menon and Gillis will become the highest-flown women in history during this mission, beating out the previous altitude record set by NASA astronaut Kathryn Sullivan.

They will fly several hundred miles higher than Sullivan, who reached an altitude of 386 miles (621 km) during the STS-31 Space Shuttle mission to help deploy the Hubble Space Telescope.

Another critical focus for Polaris Dawn, of course, is the performance of the first-ever commercial spacewalk.

Donning newly-designed extravehicular activity (EVA) suits from SpaceX, the Dawn crew will vent all the atmosphere from their spacecraft and open Crew Dragon's forward hatch for an experience shared by only a fraction of astronauts today: floating in the vacuum of space.

The focus of this spacewalk is to test the function and mobility of SpaceX's new spacesuits.

Similar in style to the sleek, white suits worn by Dragon astronauts since SpaceX's first crewed launch in 2020, these new suits feature enhanced thermal control materials and technologies to help protect the wearer from the harsh, rapidly shifting environment of space.

Two of the Dawn crew, Isaacman and Gillis, referred to during their spacewalk as EV1 and EV2, respectively, will take turns exiting Dragon entirely while utilizing a special handrail support structure connected to the hatch that SpaceX engineers have dubbed the "Skywalker."

The spacewalk will take place on the third day of Polaris Dawn's five-day flight, and will last a total of two hours from cabin depressurization through repressurization.

Then, the fourth day of the mission will come with another technology demonstration, as the Dawn crew connects to SpaceX's Starlink satellite network to transmit a "surprise" message down to Earth.

https://www.space.com/spacex-polaris-dawn-to-launch-farthest-human-spaceflight-since-apollo

https://www.spacex.com/launches/mission/?missionId=polarisdawn

2/2