Astronomy

From the 1960 astronomical catalog of

Since it began operating in 2022, the James Webb Space Telescope (JWST) has revealed some surprising things about the Universe. The latest came when a team of researchers used Webb‘s Mid-Infrared Instrument (MIRI) to observe Rho Ophiuchi, the closest star-forming nebula to Earth, about 400 light-years away. While at least five telescopes have studied the region since the 1970s, Webb’s unprecedented resolution and specialized instruments revealed what was happening at the heart of this nebula.

For starters, while observing what was thought to be a single star (WL 20S), the team realized they were observing a pair of young stars that formed 2 to 4 million years ago. The MIRI data also revealed that the twin stars have matching jets of hot gas (aka stellar jets) emanating from their north and south poles into space. The discovery was presented at the 244th meeting of the American Astronomical Society (224 AAS) on June 12th. Thanks to additional observations made by the Atacama Large Millimeter/submillimeter Array (ALMA), the team was surprised to notice large clouds of dust and gas encircling both stars.

Given the twins’ age, the team concluded that these may be circumstellar disks gradually forming a system of planets. This makes WL 20S a valuable find for astronomers, allowing them to watch a solar system take shape. As noted, the Rho Ophiuchi nebula has been studied for decades by infrared telescopes, including the Spitzer Space Telescope and the Wide-field Infrared Explorer (WISE), the Infrared Telescope Facility (IRTF) at the Mauna Kea Observatory, the Hale 5.0-meter telescope the Palomar Observatory, and the Keck II telescope.

This WL 20 star group image combines data from the Atacama Large Millimeter/submillimeter Array and the Mid-Infrared Instrument on NASA’s Webb telescope. Credit: NSF/NRAO/NASA/JPL-Caltech/B. Saxton

Infrared astronomy is necessary when studying particularly dusty nebulae since the clouds of dust and gas obscure most of the visible light of the stars within them. Thanks to its advanced infrared optics, Webb was able to detect slightly longer wavelengths using its MIRI instrument. Mary Barsony, an astronomer with the Carl Sagan Center for the Study of Life in the Universe (part of the SETI Institute), was the lead author of a new paper that describes the results. As she related in a recent NASA press statement.

“Our jaws dropped. After studying this source for decades, we thought we knew it pretty well. But we would not have known this was two stars or that these jets existed without MIRI. That’s really astonishing. It’s like having brand new eyes.”

Radio telescopes are another way to study nebulae, though they are not guaranteed to reveal the same features as infrared instruments. In the case of WL 20S, the absorbed light was visible in the submillimeter range, making ALMA the ideal choice for follow-up observations. However, the high-resolution mid-infrared data was needed to discern WL 20S as a pair of stars with individual accretion disks. This allowed the team to resolve stellar jets composed of ionized gas that is not visible at submillimeter wavelengths.

“The power of these two telescopes together is really incredible. If we hadn’t seen that these were two stars, the ALMA results might have just looked like a single disk with a gap in the middle. Instead, we have new data about two stars that are clearly at a critical point in their lives, when the processes that formed them are petering out.”

The combined MIRI and ALMA results revealed that the twin stars are nearing the end of their formation period and may already have a system of planets. Future observations of these stars with Webb and other telescopes will enable astronomers to learn more about how young stars transition from formation to their main sequence phase. “It’s amazing that this region still has so much to teach us about the life cycle of stars,” said Ressler. “I’m thrilled to see what else Webb will reveal.”

Further Reading: NASA

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Space debris is a major problem for space exploration. There are millions of pieces up there in orbit from flecks of paint to defunct satellites. It is a known challenge to space exploration creating a shell of uncontrolled debris which could cause damage to orbiting craft or astronauts. A team at Astroscale have a spacecraft in orbit whose singular purpose has been to rendezvous with a defunct Japanese upper-stage rocket module. On arrival it is to survey the debris to test approach and survey techniques to ultimately inform how we can remove them from orbit.

Space debris, or space junk, is exactly what it says; pieces of human made objects orbiting Earth that are no longer required. It’s not just unwanted items though, many pieces are the result of collisions and at speeds in excess of 28,000 kilometres per hour they pose a real threat to astronauts and operational spacecraft in low earth orbit.

Taking a bleak view, NASA scientists Donald Kessler proposed a scenario where the shear volume of debris is high enough that collisions could cascade into a chain reaction. The chain reaction of collisions could ultimately lead to an exponential growth in debris and even cut off our access to space. It may seem a pessimistic view but some computer modelling of the scenario does give strong indications that this may be the case if we don’t act now.

A map of space debris orbiting Earth. Credit: European Space Agency

There have been numerous, almost fanciful ideas proposed from great big balloons covered in sticky stuff like giant fly paper in orbit to pickup bits and bobs floating around. Nets have also been proposed even lasers to piece by piece destroy the offending objects. If I were a betting man I would go for something along the lines of a net travelling through space at similar velocity, scooping up the debris and controlling its gentle deorbit until either landed safely for collection or burnt up in the atmosphere. 

The ideas are there, what we are lacking, is data to assess their feasibility. Enter Astroscale, a company that was founded in 2013 and develops in-orbit solutions. They have been selected by the Japan Aerospace Exploration Agency – JAXA – for the first phase of Commercial Removal of Debris Demonstration. The purpose to demonstrate how the technology for removing large pieces of debris. This has led to the development of ADRAS-J (Active Debris Removal by Astroscale-Japan.)

ADRAS-J was launched on 18 February and started its rendezvous phase four days later. On 9 April it began its approach from a few hundred kilometres and from 16 April it began its automated relative navigation approach taking it to within a few hundred metres using the onboard infrared camera. On 23 May it approached to 50 metres, a first for any spacecraft to arrive in such proximity to a large piece of debris. 

The item is the upper stage of a Japanese rocket that measures 11 metres long and 4 metres in diameter. Now the two are so close, ADRAS-J will demonstrate proximity operations and collect images of the rocket to assess its movements. This is a particularly interesting object for ADRAS-J to study becausey it has no technology or infrastructure to enable docking or servicing so is a challenging piece of debris to remove.

Source : Historic Approach to Space Debris: Astroscale’s ADRAS-J Closes in by 50 Meters

The post Astroscale Closes Within 50 Meters of its Space Junk Target appeared first on Universe Today.

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It has long been thought that young stars forming near each other will be aligned in terms of their rotation, and observations from the James Webb Space Telescope have offered confirmation

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This is probably what the demise of the Hubble Space Telescope was always going to look like: components failing one by one, with no way to replace them. In the last few months, the Hubble has repeatedly gone into safe mode as one of its remaining three gyros keeps giving faulty readings. But the Hubble and the people operating it are resilient and resourceful. The telescope is back to science operations now, though in single gyro mode.

NASA has released the first image the Hubble captured in this mode, and it’s clear that the Hubble is performing well.

This image is Hubble’s contribution to a three-telescope, multi-wavelength observing effort. The James Webb Space Telescope (JWST- infrared) and the Atacama Large Millimetre/submillimetre Array (ALMA-radio) are both involved. Hubble captured this image with its Wide Field Camera 3 (WFC3.)

“Hubble’s new image of a spectacular galaxy demonstrates the full success of our new, more stable pointing mode for the telescope.”

Dr. Jennifer Wiseman, senior project scientist for Hubble, NASA’s Goddard Space Flight Center

The image shows the lenticular galaxy NGC 1546, which is about 61 million light-years away in the constellation Dorado. The galaxy is oriented so that the glow from its core lights up dust lanes. The dust absorbs starlight and then emits it again at lower wavelengths, making the dust appear brown. The core is yellowish, which indicates a population of older stars. Bright blue regions peeking out from the dust lanes are where active star formation is taking place. Background galaxies are also visible, including an edge-on view of a reddish spiral galaxy on the left.

The Hubble started its mission with six gyros, which help the telescope point itself at chosen targets. There are now only three left, and one of them is repeatedly causing problems. NASA says the gyro is experiencing ‘saturation,’ meaning it also indicates that the Hubble is at its maximum slew rate, regardless of the actual slew rate.

But as this image shows, science operations are still continuing effectively, even though NASA says there are some minor limitations in the single gyro mode. In this mode, the telescope’s view of some regions of the sky is limited. The single gyro mode is part of the telescope’s design, just in case four or five of its six gyros fail.

It’s amazing that the space telescope can operate with a single gyro. It can capture the light from objects billions of light years away while travelling at about 27,000 km/hour (17,000 mp/h). All the while, it keeps its pinpoint gaze steady. NASA describes it as keeping a laser shining on a dime over 320 km (200) miles away. The telescope requires long exposure times; sometimes, it focuses on a single time for 24 hours.

This is Hubble’s second set of six gyros. They were all replaced during a 2009 servicing mission.

In this image, astronaut Mike Massimino works to remove and replace Hubble’s Rate Sensor Units, which contain the telescope’s gyroscopes, during Servicing Mission 4 in 2009. All of Hubble’s gyroscopes were replaced during the mission. Image Credit: NASA

“Hubble’s new image of a spectacular galaxy demonstrates the full success of our new, more stable pointing mode for the telescope,” said Dr. Jennifer Wiseman, senior project scientist for Hubble at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We’re poised now for many years of discovery ahead, and we’ll be looking at everything from our solar system to exoplanets to distant galaxies. Hubble plays a powerful role in NASA’s astronomical toolkit.”

Everything has a beginning and an end, including the Hubble. Over time, gyros and other equipment will continue to fail. Just like other aged spacecraft, like the Voyager Probes, engineers and mission staff will adapt and find new ways to keep the telescope going, probably with reduced results. But one day, the space telescope will cease functioning.

Considering all that Hubble has contributed, it will be a very sad day when the telescope shares its final image with us.

The post Here’s Hubble’s First Image in its New Pointing Mode appeared first on Universe Today.

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