Tag: astronomy

Eta Carinae: The star that proved Hubble was fixed

1:02 pm

The Space Telescope Science Institute, which operates both the Hubble Space Telescope and the James Webb Space Telescope, today released a wonderful short video summarizing in images the decades of knowledge that Hubble has gleaned of the massive star Eta Carinae.

I have embedded that video below the fold. What makes Eta Carinae special is that when Hubble was pointed at it shortly after the first repair mission in 1993, that photo proved without a doubt that the telescope’s vision had been fixed. More important, the photo proved that Hubble was going to routinely show us things never before seen. In this case, we got our first sharp and unambiguous view of a massive star exploding.
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Planetary scientists fight back: “Pluto is a planet!”

6:04 pm

A group of eminent and active planetary scientists have just published a new peer-reviewed paper documenting how moons and asteroids were routinely referred to as planets from Galileo until 2006 when a very small number of scientists at an International Astronomical Union (IAU) meeting decided arbitrarily that the definition must be changed.

That IAU definition, which required an object to have a solar orbit and the vague ability of the object to clear that orbit, somehow made Pluto a non-planet. It has also never been accepted by planetary scientists, who consider it inconsistent, vague, and useless in their research as well as in teaching students about planetary science. I know this attitude is real because of what planetary scientists have told me consistently in many interviews since 2006.

The new paper appears to be part of a new aggressive campaign by planetary scientists to get that IAU definition dumped, and replace it with the definition planetary scientists have been using forever, which is that if the object is large enough for gravity to shape it into a spherical shape, it is a planet. This is still the definition they routinely use when discussing large moons like the Moon or the large Galilean moons of Jupiter or the larger moons of Saturn or Pluto itself.

It also appears, based on information at the link, that this campaign is beginning to make headway. To that I say, Hallelajuh!

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Webb successfully inserted in final orbital position at the Sun-Earth Lagrange point

3:01 pm

The James Webb Space Telescope today successfully completed a five minute firing of its engines to place it at the Sun-Earth Lagrange point dubbed L2.

Webb’s orbit will allow it a wide view of the cosmos at any given moment, as well as the opportunity for its telescope optics and scientific instruments to get cold enough to function and perform optimal science. Webb has used as little propellant as possible for course corrections while it travels out to the realm of L2, to leave as much remaining propellant as possible for Webb’s ordinary operations over its lifetime: station-keeping (small adjustments to keep Webb in its desired orbit) and momentum unloading (to counteract the effects of solar radiation pressure on the huge sunshield).

Engineers will spend the next three months aligning the segments of Webb’s large primary and secondary mirrors, while they wait for the telescope to cool down to the ambient very cold temperatures required for it to detect the tiny infrared heat emissions from very faint very very very distant objects.

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Gehrels/Swift space telescope enters safe mode

3:57 pm

The Neil Gehrels Swift observatory ceased science observations and entered safe mode on January 18, 2021, when one of its six reaction wheels experienced a failure.

It appears the other five reaction wheels, which function as gyroscopes to point the telescope accurately, are working properly. If engineers can’t recover the lost wheel, the telescope will still be able to operate with no problems.

Swift was launch seventeen years ago in order to solve the mystery of gamma ray bursts, which it did most successful. The man who most made the observatory possible, its principal scientist, Neil Gehrels, passed away in 2017, and to honor his memory the telescope was then named after him.

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Astronomers detect interstellar object invading another distant solar system

9:56 am

Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array (VLA) astronomers think they have detected for the first time an interstellar object that has invaded another distant solar system and disturbed material in its protoplanetary accretion disk.

From the paper’s abstract:

A point source ~4,700 au [astronomical unit, equal to about 100 million miles] from the binary has been discovered at both millimetre and centimetre wavelengths. It is located along the extension of a ~2,000 au streamer structure previously found in scattered light imaging, whose counterpart in dust and gas emission is also newly identified. Comparison with simulations shows signposts of a rare flyby event in action.

This data further confirms that interactions between interstellar objects occur with reasonably frequency, and can thus act to influence the formation of solar systems.

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A tumbling 1,100-foot-wide asteroid

10:04 am

Nereus tumbling on December 10th close approach
Click for full image.

Using the Goldstone radio antenna in California, scientists have been able to take some of the highest resolution radar images of the 1,100-foot-wide asteroid Nereus during its close approach to Earth on December 10, 2021.

The montage to the right, cropped to post here, shows twelve images from the 39-image sequence, which can also be viewed as an animation here.

During the asteroid’s close approach, an image resolution of about 12.3 feet (3.75 meters) per pixel was possible, revealing surface features such as potential boulders and craters, plus ridges and other topography. Asteroid Nereus’ previous approach in 2002 was near enough to Earth to reveal the asteroid’s size and overall shape, but too distant to show surface features. The new observations will also help scientists better understand the asteroid’s shape and rotation while providing them new data to further refine its orbital path around the Sun.

The asteroid will not make a similar close-approach again until 2060.

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An oblong exoplanet?

9:46 am

The uncertainty of science: Astronomers, using a variety of space telescopes, have concluded that the shape of an exoplanet in the constellation Hercules is deformed by tidal forces imposed on it by its star.

On the planet WASP-103b, tides are much more extreme. The planet orbits its star in just one day and is deformed by the strong tidal forces so drastically that its appearance resembles a rugby ball. This is shown by a new study involving researchers from the Universities of Bern and Geneva as well as the National Centre of Competence in Research (NCCR) PlanetS, published today in the scientific journal Astronomy & Astrophysics.

The data also suggests that the nearby heat of its star has also caused the exoplanet to be inflated in size.

Need I add that this result is uncertain? It requires the scientists to make many assumptions based on only a tiny bit of data, something they admit to near the end of the press release, where the releases notes that this result needs to be confirmed by future observations.

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Webb’s primary mirror successfully deployed

2:54 pm

Today engineers successfully completed the unfolding of the primary mirror on the James Webb Space Telescope.

The two wings of Webb’s primary mirror had been folded to fit inside the nose cone of an Arianespace Ariane 5 rocket prior to launch. After more than a week of other critical spacecraft deployments, the Webb team began remotely unfolding the hexagonal segments of the primary mirror, the largest ever launched into space. This was a multi-day process, with the first side deployed Jan. 7 and the second Jan. 8.

Mission Operations Center ground control at the Space Telescope Science Institute in Baltimore began deploying the second side panel of the mirror at 8:53 a.m. EST. Once it extended and latched into position at 1:17 p.m. EST, the team declared all major deployments successfully completed.

Next step over the next few months will be aligning the primary mirrors 18 segments with each other as well as the secondary mirror. First science images are expected during the summer, but do not be surprised if NASA releases some test images before then, should all be well and it obtains some eye candy.

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The very first observations of dying star before, during, and after it goes supernova

9:43 am

Astronomers have, for the very first time, observed in real time a dying red supergiant star prior to, during, and after it exploded as a supernova, thus destroying itself and collapsing into either a neutron star or a black hole.

This discovery is unprecedented because previous observations of the star prior to its explosion were discovered post-supernova, when astronomers went back and found it in archival footage. In this case the astronomers were studying the star before it exploded, and thus got a far more detailed look at its behavior.

Prior to this, all red supergiants observed before exploding were relatively quiescent: they showed no evidence of violent eruptions or luminous emission, as was observed prior to SN 2020tlf. However, this novel detection of bright radiation coming from a red supergiant in the final year before exploding suggests that at least some of these stars must undergo significant changes in their internal structure that then results in the tumultuous ejection of gas moments before they collapse.

This data will require the computer modelers and theorists to completely revise their computer models and theories for explaining the ignition of a supernova.

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Webb deploys heat radiator

8:57 am

Engineers today successfully deployed the heat radiator on the James Webb Space Telescope, allowing for unfolding of its 21-foot-diameter primary mirror over the next two days, the final step in the telescope’s deployment.

At about 8:48 a.m. EST, a specialized radiator assembly necessary for Webb’s science instruments to reach their required low and stable operating temperatures deployed successfully. The Aft Deployable Instrument Radiator, or ADIR, is a large, rectangular, 4 by 8-foot panel, consisting of high-purity aluminum subpanels covered in painted honeycomb cells to create an ultra-black surface. The ADIR, which swings away from the backside of the telescope like a trap door on hinges, is connected to the instruments via flexible straps made of high-purity aluminum foil. The radiator draws heat out of the instruments and dumps it overboard to the extreme cold background of deep space.

The whole operation took fifteen minutes.

If all goes well, by Saturday night (January 8th) engineers and scientists will have in their hands the world’s largest infrared telescope, and it will be operating in space. Actual scientific observations however will not begin immediately. It will still take several weeks for the telescope to cool down to the very cold temperatures it needs to see faint infrared objects, and then about five more months of additional testing to precisely align the mirrors while figuring out how the telescope itself operates in space.

We should expect the first raw and unaligned infrared images in about a month, with the first official observations released sometime in the very early summer.

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Webb engineers successfully deploy the telescope’s secondary mirror

2:50 pm

Engineers today confirmed that the secondary mirror for the James Webb Space Telescope has successfully deployed, its tripod structure unfolding and locking into place.

In addition the cover protecting the Mid-Infrared Instrument (MIRI) was successfully unlocked. The instrument’s science team did not open the cover yet because the telescope hasn’t yet cooled enough, its sun shield only in place for a day or so.

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Webb: Sun shield deployment completed

3:32 pm

Engineers today successfully completed the full deployment of the sun shield of the James Webb Space Telescope.

The unfolding and tensioning of the sunshield involved 139 of Webb’s 178 release mechanisms, 70 hinge assemblies, eight deployment motors, roughly 400 pulleys, and 90 individual cables totaling roughly one quarter of a mile in length. The team also paused deployment operations for a day to work on optimizing Webb’s power systems and tensioning motors, to ensure Webb was in prime condition before beginning the major work of sunshield tensioning.

The process took eight days, and was by far the most complex such remote deployment ever attempted by an unmanned spacecraft. The shield is now in place to shade Webb from sunlight and heat and thus allow it to observe very faint infrared objects billions of light years away.

Next comes the deployment of Webb’s secondary mirror, followed by the unfolding of its main mirror.

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Webb deployment resumes, with continuing success

9:50 am

After a day delay to assess the telescope’s earlier operation in space, engineers yesterday resumed the deployment of the James Webb Space Telescope’s sun shield.

First they began tensioning the shield’s first of five layers, completing that operation in about five and a half hours.

Next the engineers proceeded to tighten layers two and three, completing that task in about three hours.

Today they have begun tightening the last two layers. A live stream of this slow and relatively unexciting process (as long as nothing goes wrong) is available from NASA here.

Based on what has been done so far, it appears that the deployment of the sun shield, considered the most challenging part of Webb’s deployment, is going to complete successfully. While the unfolding and deployment of the mirror still must be done, getting the sun shield deployed eliminates one of the great concerns that has kept both astronomers and engineers awake nights for decades.

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The unfurling of Webb’s sun shield begins

5:18 pm

Engineers have begun the multi-day unfurling and deployment of the sun shield on the James Webb Space Telescope.

The first step is to deploy two booms on each side of the telescope that draw the shield itself outward.

The deployment of the first boom was held up several hours to give engineers time to make sure the protective covers had, in fact, rolled off to the side of the sunshade pallets as required.

“Switches that should have indicated that the cover rolled up did not trigger when they were supposed to,” NASA said in a blog post. “However, secondary and tertiary sources offered confirmation that it had.”

“The deployment of the five telescoping segments of the motor-driven mid-boom began around 1:30 p.m., and the arm extended smoothly until it reached full deployment,” NASA said.

Engineers then sent commands to deploy the second sunshade boom, which extended smoothly and locked in place at 10:13 p.m., finally giving Webb its iconic kite-like shape.

Next the shield has to be tightened in place, which will also separate and tighten in place the shield’s five layers. According to the schedule, the four layers will be tensioned today, with the fifth tomorrow.

The step-by-step deployment is outlined in detail here, and updates to the most recently completed step after it is finished.

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1st stage of Webb sun shield deployment completed

9:29 am

The deployment of the forward and aft pallets required to support the sun shield for the James Webb Space Telescope has apparently been successfully completed.

The link takes you to the website that outlines each step in Webb’s entire 30-day deployment sequence, and is updated to show you the next required step as the process continues. Though I have yet to see any official announcement, this page now shows that both pallets have successfully unfolded and that the next step is removal of the covers that have protected the sun shield membrene during assembly and launch.

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Deployment of Webb’s critical sunshield has begun

9:03 am

The deployment of the complex sunshield for the James Webb Space Telescope has successfully begun, and if all continues as planned, will continue for the next five days.

Early this afternoon the Webb mission operations team concluded the deployment of the first of two structures that hold within them Webb’s most unpredictable and in many ways complicated component: the sunshield.

The structures – called the Forward and Aft Unitized Pallet Structures – contain the five carefully folded sunshield membranes, plus the cables, pulleys, and release mechanisms that make up Webb’s sunshield. The team completed the deployment of the forward pallet at approximately 1:21 p.m. EST, after beginning the entire process about four hours earlier. The team will now move on to the aft pallet deployment.

Over the next five days the aft pallet must be deployed, along with a tower assembly that will raise the telescope itself away from the sunshield to better keep Webb cold. After this the deployment of the many additional parts of the shield will take place, a process that is probably the most complex in-space spacecraft deployment ever.

It is good news that so far all is proceeding as planned, and gives hope that all will continue to do so.

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Webb: Course correction burn and main antenna deployment both a success

2:11 pm

Over the weekend engineers for the James Webb Space Telescope successfully completed a course correction burn that put the telescope on route to is planned location a million miles from Earth.

They also successfully deployed the telescope’s main antenna.

Other steps completed on Webb’s first full day in space included the switch-on of temperature sensors and strain gauges on the telescope, used for monitoring Webb’s thermal and structural parameters, NASA said. The antenna release and first mid-course correction burn set the stage for the next step of Webb’s post-launch commissioning — the deployment and tensioning of the observatory’s tennis court-sized sunshield.

These next steps are likely the most risky part of the telescope’s deployment, as it involves the most moving parts and is the most complex. While similar such unfoldings have been done successfully many times before, they have also been the very prone to failure.

The sunshield must work however for Webb to operate. As an infrared telescope, it essentially detects heat, and if it is not well shielded from sunlight its images will be fogged.

The deployment is presently set to begin tomorrow.

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Webb successfully launched

8:13 am

Early this morning an Ariane 5 rocket successfully launched the James Webb Space Telescope from French Guiana.

The key moment that indicated the launch was success was, after Webb was deployed from the rocket’s upper stage, its solar panels deployed and the telescope began receiving power from them.

The launch itself was something that has been done by the Ariane 5 rocket many many times, without failure. Now comes the part of this operation that has never been done before.

Now “30 days of terror” begin, as JWST starts its career in space. First, it will take the space telescope 30 days to reach the start of its halo orbit at L2. On its way, the telescope must unfurl its 18 gold-plated beryllium mirror segments using 132 actuators. It will also have to deploy its five-layer, origami sunshield and cool down to below 50K (-223°C or -370°F) to begin the start of science operations in 2022.

NASA has a webpage that shows the step-by-step deployment, and allows you to see the status at any time during the next 30 days.

After almost twenty years of development and a budget that went 20x over its original estimate, let’s us all hope that Webb deploys properly and begins collecting data as intended. If it does, it will allow astronomers to make ground-breaking discoveries, and we shall gain a better idea of what lies hidden behind that black sky that surrounds us.

As for the 2021 launch race, this is the updated leader board:

49 China
31 SpaceX
22 Russia
7 Europe (Arianespace)

China will likely be the winner in the national rankings, 49 to 48 over the U.S. This was the 130th successful launch in 2021, only the second time in the history of space exploration that the world reached that number of launches in a single year.

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Webb telescope reaches launchpad on Ariane 5 + how to watch launch

9:14 am

The James Webb Space Telescope, stacked on top of Arianespace’s Ariane 5 rocket, has finally reached its launchpad in French Guiana after twenty years of development costing 20 times its original budget.

The launch itself is now scheduled for December 25, 2021 at 7:20 am (Eastern). It will be live streamed by both NASA (in English) and Arianespace (with options in English, French, or Spanish).

I have embedded below NASA’s feed. As always, expect NASA to pump you with lots of propaganda during its live stream.

When all is said and done, Webb has the chance to show us things about the universe we’ve never seen before. Optimized for deep space cosmology, it will provide us a window into the earliest moments of the universe’s existence. And is infrared capabilities will allow it to peer into many nearer places obscured by dust with a resolution unmatched by previous telescopes.

Keep your fingers crossed all goes as planned.
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Astronomers detect 70 to 170 free floating exoplanets

11:03 am

The uncertainty of science: Astronomers today announced that they think they have detected from 70 to 170 exoplanets in a nearby star-forming region that are apparently free-floating, unattached to any star or solar system.

The astronomers also combined the vast number of images available in public astronomical archives with the new deep wide-field observations obtained with the best infrared and optical telescopes on the ground and in space. Using over 80,000 wide-field images adding up to around 100 terabytes and spanning 20 years, they identified at least 70, and up to as many as 170 of these Jupiter-sized planets, as members of the Upper Scorpius association among the background stars and galaxies.

If confirmed, this discovery more than doubles the number of free-floating planets known.

The discovery was made by first using the motion of the stars to pinpoint which ones belonged to the Upper Scorpius star-forming region. The astronomers then compared this data with past archival telescopic images.

Though intriguing, a great deal of skepticism of this discovery is required. The press release is very vague about some points. For example, no explanation is given on how they measured the mass of these objects to determine they were Jupiter-sized.

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