@JohnBarentine@astrodon.social
@JohnBarentine@astrodon.social avatar

JohnBarentine

@JohnBarentine@astrodon.social

Astronomer. Historian. Author. Small business owner. Arizona native. Proud LGBT American. 🏳️‍🌈 Retiring to asteroid 14505. Questioning everything; occasionally getting in trouble for it. Toots about #Astronomy, #LightPollution, #DarkSkies, #Satellites, #SciencePolicy, #History and more.

This profile is from a federated server and may be incomplete. Browse more on the original instance.

JohnBarentine, to random
@JohnBarentine@astrodon.social avatar

Results of a recent lighting survey in Rome showed that "walking comfort was affected by mean luminance of whole scene, of sidewalk, of lateral wall and of human body; luminance also influenced the perception of street lighting intensity and uniformity and, to a lesser extent, the visibility of other people and of background."

https://www.tandfonline.com/doi/full/10.1080/13574809.2024.2351914

JohnBarentine, to random
@JohnBarentine@astrodon.social avatar

Lights Out Connecticut and the Menunkatuck Audubon Society are jointly hosting a webinar called "Humans and The Night Sky: Our Lost Heritage" on Tuesday, 4th June at 7 PM EDT (2300 UTC). Register for the event on: https://www.mobilize.us/audubon-chapters/event/628205/

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

"'It’s difficult to say exactly how many asteroids will be lost… but preliminary results suggest that for every five near-Earth asteroids we discover, we lose one solely due to constellation interference. That’s if no mitigation measures are taken.'"

https://english.elpais.com/technology/2024-05-18/spacex-satellites-threaten-to-hide-asteroids-that-pose-danger-to-humanity.html

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

Re-entries: anytime, anywhere!

Since militaries are the prime customer, probably: all the time, and everywhere.

https://spacenews.com/inversion-space-targets-military-market-with-warehouses-in-space/

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

An initiative by "astrophysicists, policy experts, artists, and stargazers" to help people submit comments on the @FCC proposal to allow direct-to-device cell phone service from LEO satellites: https://www.kesslerrebellion.com/take-action

JohnBarentine, to Astronomy
@JohnBarentine@astrodon.social avatar

Hats off to the Royal Astronomical Society for tackling this issue. "Urgent action is needed to address an insidious and systemic problem within the world of and , a damning new report warns."

https://ras.ac.uk/news-and-press/news/urgent-change-needed-tackle-bullying-astronomy-and-geophysics

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

“We’ve talked in the past about there being academic evidence, engineering studies. What we are actually seeing now with those satellites in operation is empirical evidence. You see the noise floor on our satellites increase to the degree that services cannot be provided.”

https://spacenews.com/omnispace-reports-interference-from-starlink-direct-to-device-payloads/

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

"This work presents a photometric model of the Starlink satellites based on the Bidirectional Reflectance Distribution Function (BRDF) using millions of photometric observations. ... In addition to assessing the light pollution and guiding the development of response measures, accurate photometric models of satellites can also play an important role in areas such as space situational awareness."

https://arxiv.org/abs/2403.05831

JohnBarentine, to random
@JohnBarentine@astrodon.social avatar

Artificial light is good and beneficial to humanity. But it's also possible to have too much of a good thing.

Follow the Five Principles for Responsible Outdoor Lighting: https://darksky.org/resources/guides-and-how-tos/lighting-principles/

JohnBarentine, to til
@JohnBarentine@astrodon.social avatar

that the American Enterprise Institute has built what looks to be a useful dashboard based on data aggregated by @planet4589 and @celestrak to visualize lots of information about trends in launches, and .

https://spacedata.aei.org/

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

Bad news for radio astronomy AND optical astronomy. Not only is 'Supplemental Coverage from Space' (aka direct-to-cell) transmission unregulated at this point, but the 2nd generation of satellites will be monstrously large reflectors of sunlight.

https://www.reuters.com/business/media-telecom/att-ast-spacemobile-tie-up-provide-space-based-broadband-network-2024-05-15

JohnBarentine, to sustainability
@JohnBarentine@astrodon.social avatar

Issued today. "There is a need for international coordination to foster transparency, clarity and consistency of relevant policies and regulations, ... to effectively address and promote the safety and of activities."

https://www.unportugal.ptspace.pt/wp-content/uploads/2024/05/Lisbon_Declaration_on_Outer_Space.pdf

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@richard This declaration reads to me mainly as an affirmation of the existing process at COPUOS and doesn't really contain anything new. Maybe it's subtly pushing back on the Artemis Accords (as more countries sign them) as being too U.S.-centric. I'm not sure; I knew nothing about this conference or the declaration until it popped up earlier today on social media.

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@richard As an outsider looking in at the COPUOS process in recent years, it's painfully slow (by design). It's a consensus body, and any one member State can hold up the proceedings (and States have done just that). It seems ill-suited to govern a realm where the pace of change in recent years has been lightning-fast. Yet every year COPUOS debates whether to continue even talking about these issues.

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@richard Agreed. It seems sort of one-sided, which is why I mentioned Artemis. OST signatories have recently breached the treaty, indicating that they won't be bound by it any airtight manner. And I'm afraid that we're looking at outright acts of war in space sooner rather than later (and nothing can stop that now).

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@richard 😅

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

"While there are still hurdles to overcome and challenges to solve before LSST can deliver on its extraordinary promises, thankfully, dealing with tiny bits of space junk likely won’t be one of them."

https://aasnova.org/2024/05/15/huge-survey-vs-tiny-space-junk/

(There's always a "yes, but".)

Yes, but: those tiny bits of debris contribute most to an expected rise in diffuse night sky brightness for ALL observatories.

See: https://academic.oup.com/mnrasl/article/504/1/L40/6188393

and:

https://www.aanda.org/10.1051/0004-6361/202037501

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@silberspur That's a great question! The second paper I linked (by Bassa, Hainaut and Galadí-Enríquez) argues that intact satellites aren't the problem where diffuse night sky brightness is concerned. The smallest particles are the biggest contributor. If there were no small particles and only large satellites, the effect would be ~1% at most. But it could be considerably worse than 10% if, as Oli Hainaut said in presenting this work, the satellites"grind themselves into dust".

JohnBarentine, to Astronomy
@JohnBarentine@astrodon.social avatar

Today's H-alpha in good seeing conditions at 17:00 UTC.

There are not many days on which H-alpha views of the Sun include prominences that visualize the magnetic field lines above active regions particularly well, but today is definitely one of those days.

A pseudo-coronographic image of the limb of the Sun in the light of hydrogen alpha showing prominences extending above the solar limb in bright red hues. The solar disc is rendered artificially black. The prominence shown here curls around the magnetic field lines of an active region just beyond the solar limb, forming open and closed loops.

JohnBarentine, to space
@JohnBarentine@astrodon.social avatar

So, which is it?

"Musk's Starlink satellites disrupted by major solar storm" https://www.cnbc.com/amp/2024/05/11/musks-starlink-satellites-disrupted-by-major-solar-storm.html

or

"SpaceX Starlink satellites doing just fine after weekend solar storm, company says" https://www.space.com/spacex-starlink-solar-storm-healthy-satellites ?

It can't be both. 🤷🏼‍♂️

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@reedmideke That's what I am trying to figure out. The company's communications make it sound like nothing is wrong at all, but its statement that "on-station" satellites are fine may be telling...

Also, it's unclear whether a distinction is being made between signal interruptions and possible damage to satellites.

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@volkris It would be great if someone, either among the media or at the company, would clear that up.

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@mimblewimble Evidently they didn't lose any objects in low parking orbits (unlike in 2022, which is good), but there were some service disruptions (which is not unexpected).

JohnBarentine, to Law
@JohnBarentine@astrodon.social avatar

New law review: "This Note argues that the existing tools in the Clean Water Act provide authority for the U.S. Environmental Protection Agency (EPA) to regulate light pollution and preserve the integrity of the nation’s waters."

https://scholarship.law.wm.edu/wmlr/vol65/iss6/6/

JohnBarentine,
@JohnBarentine@astrodon.social avatar

The review also argues that “regulation of light pollution does not trigger the Major Questions Doctrine following West Virginia v. EPA”.

This is the completely-made-up-by-SCOTUS doctrine that federal agencies shouldn't decide "major" policy questions. https://en.wikipedia.org/wiki/Major_questions_doctrine

JohnBarentine, to Astronomy
@JohnBarentine@astrodon.social avatar

"In general, space rocks larger than a kilometre can’t rotate more than once every 2.2 hours because they would break apart. But smaller like can withstand much faster spins because they are more compact."

https://www.newscientist.com/article/2428473-asteroid-that-broke-up-over-berlin-was-fastest-spinning-one-ever-seen/

JohnBarentine,
@JohnBarentine@astrodon.social avatar

@schnedan Apologies that I did not read your comment until now! I think you are correct that the bulk modulus of the asteroid (which in turn depends on its detailed composition) determines the critical spin frequency at which breakup would occur. Then again, we see relatively fast rotation speeds in, e.g., comet nuclei, which have almost no metal.

  • All
  • Subscribed
  • Moderated
  • Favorites
  • •
  • JUstTest
  • tacticalgear
  • rosin
  • Youngstown
  • mdbf
  • ngwrru68w68
  • slotface
  • khanakhh
  • ethstaker
  • everett
  • kavyap
  • thenastyranch
  • DreamBathrooms
  • magazineikmin
  • anitta
  • osvaldo12
  • InstantRegret
  • Durango
  • cisconetworking
  • modclub
  • cubers
  • GTA5RPClips
  • tester
  • normalnudes
  • Leos
  • provamag3
  • megavids
  • lostlight
  • All magazines
    •