China's mysterious space plane returns to Earth after 9-month orbital mission

May 8, 2023

The second orbital mission of China's robotic space plane has come to a close.

The mysterious reusable vehicle touched down Monday (May 8) at the Jiuquan Satellite Launch Center in northwest China, wrapping up a 276-day mission to Earth orbit, according to China's state-run Xinhua news agency.

"The success of the experiment marks an important breakthrough in China's research on reusable spacecraft technologies, which will provide more convenient and affordable round-trip methods for the peaceful use of space in the future," Xinhua wrote in a brief update on Monday.

The space plane launched from Jiuquan on Aug. 4, 2022, kicking off a mission short on details but long on intrigue.

On Oct. 31, for example, the vehicle ejected something into orbit. Some experts speculated(opens in new tab) that the object was a service module, possibly indicating that the space plane was getting ready to return to Earth.

Others posited that the new free flyer was a small satellite(opens in new tab) designed to monitor the Chinese space plane — perhaps the correct guess, given how much longer the robotic spacecraft stayed aloft.

The Chinese space plane's first orbital mission, which took place in September 2020, lasted just two days.

Western experts think the vehicle is roughly similar to the U.S. Space Force's robotic X-37B, which is about 29 feet (8.8 meters) long. The U.S. military is similarly tight-lipped about the X-37B, which has flown six orbital missions to date, the longest of which lasted 909 days.

https://www.space.com/china-space-plane-lands-may-2023

Aeolus’ fiery demise to set standard for safe reentry

May 8, 2023

Having exceeded its planned life in orbit, the 1360-kg satellite is running out of fuel. Ensuring that enough fuel remains for a few final manoeuvres, ESA’s spacecraft operators will bring Aeolus back towards our planet’s atmosphere for its inevitable demise.

They will aim the mission towards the ocean, further reducing the very small chance that fragments could cause harm should any reach Earth’s surface.

This is the first assisted reentry of its kind and sets a precedent for a responsible approach to reduce the ever-increasing problem of space debris and uncontrolled reentries.

Why is Aeolus coming home?

Launched in 2018, Aeolus has outlived its planned three-year life in space by more than 18 months. During its mission, its trailblazing wind-mapping laser, which at one stage was thought a nigh-impossible feat of engineering, has significantly improved weather forecasts worldwide.

Aeolus has been hailed as one of the most successful missions ever built and flown by ESA. As an Earth Explorer research mission, it was designed to demonstrate new space technology, but it became one of the highest impact-per-observation weather satellites, and its laser is still performing as well as ever.

However, Aeolus’ fuel is now almost depleted and orbiting low, at an altitude of just 320 km, means it is already being caught up by Earth’s wispy atmosphere.

Speeding up Aeolus’ return is the Sun.

Solar flares and coronal mass ejections release matter and radiation, and when this washes past Earth, it increases the density of Earth’s atmosphere. Intense solar activity in recent months means that the satellite has been using even more fuel to remain in orbit. For Aeolus, it’s been like running against the wind.

This is why, after five years of spectacular science, ESA’s wind mission ended operations on 30 April 2023.

Making use of this phase, scientists have put its instrument into a special mode to perform end-of-life activities that will help to prepare the Aeolus-2 follow-on mission, which like a phoenix will emerge from the ashes of its pathfinding predecessor.

Aeolus’ final breaths

Over the next few months, Aeolus will descend naturally from its current altitude of 320 km to 280 km. At this point, spacecraft operators at ESA’s mission control centre, ESOC, in Darmstadt, Germany, will gradually lower it to 150 km above Earth’s surface. The satellite will burn up as it descends to around 80 km.

As populated regions make up a relatively small percentage of Earth’s surface, the chance of a re-entry causing any harm is exceptionally low.

The final date depends on how solar activity speeds up the process, but Aeolus is expected to be no more before the end of August.

Aeolus engineers and industry partners have carefully worked out how to best position Aeolus in Earth’s atmosphere to target open ocean waters upon reentry, hugely reducing the amount of land over which pieces fragments could fall.

ESA’s Aeolus Mission Manager, Tommaso Parrinello, said, “The exact details on the reentry approach and series of manoeuvres and operations, as well as a more detailed timeline will be made public in mid-June.

“For now, we can anticipate that we are targeting the best ocean corridor to reenter.”

With the assisted reentry of Aeolus, ESA is clearing the way for future missions to continue taking the pulse of our planet. They can only do this if Earth’s orbits aren’t filled with dangerous space debris, and safety is at the forefront of end-of-life activities.

https://www.esa.int/Applications/Observing_the_Earth/FutureEO/Aeolus/Aeolus_fiery_demise_to_set_standard_for_safe_reentry

Webb Looks for Fomalhaut’s Asteroid Belt and Finds Much More

May 8, 2023

Astronomers used NASA’s James Webb Space Telescope to image the warm dust around a nearby young star, Fomalhaut, in order to study the first asteroid belt ever seen outside of our solar system in infrared light. But to their surprise, the dusty structures are much more complex than the asteroid and Kuiper dust belts of our solar system. Overall, there are three nested belts extending out to 14 billion miles (23 billion kilometers) from the star; that’s 150 times the distance of Earth from the Sun. The scale of the outermost belt is roughly twice the scale of our solar system’s Kuiper Belt of small bodies and cold dust beyond Neptune. The inner belts – which had never been seen before – were revealed by Webb for the first time.

The belts encircle the young hot star, which can be seen with the naked eye as the brightest star in the southern constellation Piscis Austrinus. The dusty belts are the debris from collisions of larger bodies, analogous to asteroids and comets, and are frequently described as ‘debris disks.’ “I would describe Fomalhaut as the archetype of debris disks found elsewhere in our galaxy, because it has components similar to those we have in our own planetary system,” said András Gáspár of the University of Arizona in Tucson and lead author of a new paper describing these results. “By looking at the patterns in these rings, we can actually start to make a little sketch of what a planetary system ought to look like – If we could actually take a deep enough picture to see the suspected planets.”

The Hubble Space Telescope and Herschel Space Observatory, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), have previously taken sharp images of the outermost belt. However, none of them found any structure interior to it. The inner belts have been resolved for the first time by Webb in infrared light. “Where Webb really excels is that we're able to physically resolve the thermal glow from dust in those inner regions. So you can see inner belts that we could never see before,” said Schuyler Wolff, another member of the team at the University of Arizona.

Hubble, ALMA, and Webb are tag-teaming to assemble a holistic view of the debris disks around a number of stars. “With Hubble and ALMA, we were able to image a bunch of Kuiper Belt analogs, and we've learned loads about how outer disks form and evolve,” said Wolff. “But we need Webb to allow us to image a dozen or so asteroid belts elsewhere. We can learn just as much about the inner warm regions of these disks as Hubble and ALMA taught us about the colder outer regions.”

These belts most likely are carved by the gravitational forces produced by unseen planets. Similarly, inside our solar system Jupiter corrals the asteroid belt, the inner edge of the Kuiper Belt is sculpted by Neptune, and the outer edge could be shepherded by as-yet-unseen bodies beyond it. As Webb images more systems, we will learn about the configurations of their planets.

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Fomalhaut's dust ring was discovered in 1983 in observations made by NASA's Infrared Astronomical Satellite (IRAS). The existence of the ring has also been inferred from previous and longer-wavelength observations using submillimeter telescopes on Mauna Kea, Hawaii, NASA’s Spitzer Space Telescope, and Caltech's Submillimeter Observatory.

“The belts around Fomalhaut are kind of a mystery novel: Where are the planets?” said George Rieke, another team member and U.S. science lead for Webb’s Mid-Infrared Instrument (MIRI), which made these observations. “I think it's not a very big leap to say there's probably a really interesting planetary system around the star.”

“We definitely didn't expect the more complex structure with the second intermediate belt and then the broader asteroid belt,” added Wolff. “That structure is very exciting because any time an astronomer sees a gap and rings in a disk, they say, ‘There could be an embedded planet shaping the rings!’”

Webb also imaged what Gáspár dubs “the great dust cloud,” which may be evidence for a collision occurring in the outer ring between two protoplanetary bodies. This is a different feature from a suspected planet first seen inside the outer ring by Hubble in 2008. Subsequent Hubble observations showed that by 2014 the object had vanished. A plausible interpretation is that this newly discovered feature, like the earlier one, is an expanding cloud of very fine dust particles from two icy bodies that smashed into each other.

The idea of a protoplanetary disk around a star goes back to the late 1700s when astronomers Immanuel Kant and Pierre-Simon Laplace independently developed the theory that the Sun and planets formed from a rotating gas cloud that collapsed and flattened due to gravity. Debris disks develop later, following the formation of planets and dispersal of the primordial gas in the systems. They show that small bodies like asteroids are colliding catastrophically and pulverizing their surfaces into huge clouds of dust and other debris. Observations of their dust provide unique clues to the structure of an exoplanetary system, reaching down to earth-sized planets and even asteroids, which are much too small to see individually.

https://www.nasa.gov/feature/goddard/2023/webb-looks-for-fomalhaut-s-asteroid-belt-and-finds-much-more

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