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  #1  
Old 09-08-2023, 01:10 PM
Vanel Vanel is offline
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Default Orbital Debris 101

The "Stand up Space Greta" thread has once again driven home how little people actually know about orbital debris. Since this is my area at NASA, I figured I would give a short overview of what we know about OD. This will be based on numbers, observations and physical models, not on speculation, opinion and op eds by science writers and other media. I get enough of that at work because administrations tend to pay more attention to what's on CNN than the data, which naturally leads to some stupid decisions by the high and mighty.

Everything is political, and Earl is quite correct in that governments are tombstone agencies. No space agency, anywhere in the world, is currently doing anything that will have an impact on the OD environment for decades to come. It would indeed take a major event or catastrophe to change this situation. Barring such an event, politics, both internal and international, will not allow for significant progress.

So on to the facts. Numero uno is to define where in Earth orbit OD poses a significant risk. For convenience, let's take significant to be any altitude where the number of OD impacts per unit area exceeds the number of meteoroid impacts on that same area. Meteoroids are the "natural background" - always have been there, always will be.

The attached plot shows the percentage of impacts by OD and meteoroids as a function of altitude. Since we are interested in stuff that can hurt spacecraft, the threshold has been set to particles that can penetrate a 1 mm aluminum plate. This would correspond to very thin spacecraft walls or containers.

Note: Manned vehicles are very robust compared to other spacecraft. ISS shields on the U.S. segments can stop a 2 inch piece of debris, making it the "tank" of LEO. However, we do worry a great deal about crew on EVA. A particle 0.5 mm in diameter can open a 1 mm hole in a suit, resulting in a fatality as the astronaut could not get inside and repressurize in time. Since we cannot see these things coming, it is something crew on EVAs think about a fair amount. Have to admire their bravery!

Looking at the plot, you can see that the meteoroid and orbital debris risk at ISS altitude is about equal. But the OD hazard is rising rapidly, peaking at sun synchronous altitudes around 1000 km. There 90% of the impacts on a surface are due to OD - completely overwhelming the natural meteoroid environment! Beyond 2000 km, the OD percentage falls off, with meteoroids becoming dominant at MEO altitudes and beyond.

Take away points:

1) OD is strictly a low Earth orbit issue.
2) It is very bad at sun synchronous altitudes because that region is the "Boardwalk and Park Place" of LEO. Everyone - from imagers, to spy sats, to climate monitoring satellites, to mega constellations - wants to fly there. GEO has its uses, but SSO is where all the action is.

In the next post, I'll briefly outline the sources of orbital debris, including which nations are the "bad boys."

Unless you guys want me to stop - I'll gladly do so, so don't hesitate to yell.
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  #2  
Old 09-08-2023, 01:43 PM
Ltvscout Ltvscout is offline
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Once again, thank you for the expert view, Bill!
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Old 09-08-2023, 02:28 PM
A Fish Named Wallyum A Fish Named Wallyum is online now
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Originally Posted by Ltvscout
Once again, thank you for the expert view, Bill!

Expert? He can't even tell a decent horoscope and he calls himself an astrologer.
I was just thinking about you today, Bill. Doing any flying lately? Anything blog-worthy? 2022 was, like, years ago.
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Old 09-08-2023, 06:25 PM
Vanel Vanel is offline
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Originally Posted by A Fish Named Wallyum
Expert? He can't even tell a decent horoscope and he calls himself an astrologer.


Sigh. I’d probably have more money if I was an astrologer.

Quote:
I was just thinking about you today, Bill. Doing any flying lately? Anything blog-worthy? 2022 was, like, years ago.


Flying a few about once a month. As far as the blog, I occasionally feel some guilt, but I write so much at work that I just can’t muster the energy for the blog.

I do need to put a coat of paint on the Sabre clone and finish up some other projects. Long on ambition, short on motivation and time.
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  #5  
Old 09-08-2023, 10:32 PM
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Originally Posted by Vanel
Sigh. I’d probably have more money if I was an astrologer.

Because they are real and they predict the future so they all get super rich on stocks, betting, etc.

I'm glad you posted this, as I've often wondered about the odds. I think the Challenger coming back with a damaged window from a paint fleck really drove it home for me. That was early in the program, so probably around '83-'85.
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Old 09-09-2023, 08:10 AM
frognbuff frognbuff is offline
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Quote:
Originally Posted by Vanel
The "Stand up Space Greta" thread has once again driven home how little people actually know about orbital debris. Since this is my area at NASA, I figured I would give a short overview of what we know about OD. This will be based on numbers, observations and physical models, not on speculation, opinion and op eds by science writers and other media. I get enough of that at work because administrations tend to pay more attention to what's on CNN than the data, which naturally leads to some stupid decisions by the high and mighty.

Everything is political, and Earl is quite correct in that governments are tombstone agencies. No space agency, anywhere in the world, is currently doing anything that will have an impact on the OD environment for decades to come. It would indeed take a major event or catastrophe to change this situation. Barring such an event, politics, both internal and international, will not allow for significant progress.

So on to the facts. Numero uno is to define where in Earth orbit OD poses a significant risk. For convenience, let's take significant to be any altitude where the number of OD impacts per unit area exceeds the number of meteoroid impacts on that same area. Meteoroids are the "natural background" - always have been there, always will be.

The attached plot shows the percentage of impacts by OD and meteoroids as a function of altitude. Since we are interested in stuff that can hurt spacecraft, the threshold has been set to particles that can penetrate a 1 mm aluminum plate. This would correspond to very thin spacecraft walls or containers.

Note: Manned vehicles are very robust compared to other spacecraft. ISS shields on the U.S. segments can stop a 2 inch piece of debris, making it the "tank" of LEO. However, we do worry a great deal about crew on EVA. A particle 0.5 mm in diameter can open a 1 mm hole in a suit, resulting in a fatality as the astronaut could not get inside and repressurize in time. Since we cannot see these things coming, it is something crew on EVAs think about a fair amount. Have to admire their bravery!

Looking at the plot, you can see that the meteoroid and orbital debris risk at ISS altitude is about equal. But the OD hazard is rising rapidly, peaking at sun synchronous altitudes around 1000 km. There 90% of the impacts on a surface are due to OD - completely overwhelming the natural meteoroid environment! Beyond 2000 km, the OD percentage falls off, with meteoroids becoming dominant at MEO altitudes and beyond.

Take away points:

1) OD is strictly a low Earth orbit issue.
2) It is very bad at sun synchronous altitudes because that region is the "Boardwalk and Park Place" of LEO. Everyone - from imagers, to spy sats, to climate monitoring satellites, to mega constellations - wants to fly there. GEO has its uses, but SSO is where all the action is.

In the next post, I'll briefly outline the sources of orbital debris, including which nations are the "bad boys."

Unless you guys want me to stop - I'll gladly do so, so don't hesitate to yell.



Seems way out of date. Where is Starlink? They cause the launch business WAAAY more headaches than O3B!
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Old 09-09-2023, 08:49 AM
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Winston2021 Winston2021 is offline
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Quote:
Originally Posted by Vanel
The "Stand up Space Greta" thread has once again driven home how little people actually know about orbital debris.
Rather than smearing me in a separate thread with a post that misrepresents what I said, answer me directly.

I DID NOT say that it isn't a major problem. I said it doesn't merit Greta levels of hype since it is unlike the catastrophic climate change hysteria an ACTUAL problem and, since it is, it is in everyone's best interest to minimize it.

I also said that the HUGE constellations of networked satellites planned is concerning although, supposedly, SpaceX has methods to deorbit them when the have left their useful life.

What I DIDN'T say, but should have, is that by involving that ignorant little propagandist in this topic, the topic will be discredited.

Respond to this post with an apology.
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Old 09-09-2023, 08:53 AM
Vanel Vanel is offline
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Originally Posted by frognbuff
Seems way out of date. Where is Starlink? They cause the launch business WAAAY more headaches than O3B!


They are there - the data is from earlier this year. I just chose not to mark them. Get tired of Starling.
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Old 09-09-2023, 08:59 AM
Vanel Vanel is offline
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Originally Posted by Winston2021
Rather than smearing me in a separate thread with a post that misrepresents what I said, answer me directly.

I DID NOT say that it isn't a major problem. I said it doesn't merit Greta levels of hype since it is unlike the catastrophic climate change hysteria an ACTUAL problem and, since it is, it is in everyone's best interest to minimize it.

What I DIDN'T say, but should have, is that by involving that ignorant little propagandist in this topic, the topic will be discredited.


I had no intention of smearing you. I simply seized an opportunity to pass on information since Space Greta is doing her hype. I created a separate topic devoted specifically to orbital debris to avoid intruding on your thread.

Get the chip off your shoulder, dude.
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  #10  
Old 09-09-2023, 09:09 AM
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Winston2021 Winston2021 is offline
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Quote:
Originally Posted by Vanel
I had no intention of smearing you. I simply seized an opportunity to pass on information since Space Greta is doing her hype. I created a separate topic devoted specifically to orbital debris to avoid intruding on your thread.

Get the chip off your shoulder, dude.
Thanks... kinda'. You should have directed the "how little people know" directly at her since that wasn't obvious.

By the way, this isn't directed at you, just at modern "science" in general:

"It is simply no longer possible to believe much of the clinical research that is published, or to rely on the judgment of trusted physicians or authoritative medical guidelines. I take no pleasure in this conclusion, which I reached slowly and reluctantly over my two decades as editor of The New England Journal of Medicine." - Marcia Angell (2009)

"The case against science is straightforward: much of the scientific literature, perhaps half, may simply be untrue. Afflicted by studies with small sample sizes, tiny effects, invalid exploratory analyses, and flagrant conflicts of interest, together with an obsession for pursuing fashionable trends of dubious importance, science has taken a turn towards darkness." - Richard Horton, editor of The Lancet (2015)

"Journals have devolved into information laundering operations for the pharmaceutical industry." - Richard Horton, editor of The Lancet (2004)

----------

Why Most Published Research Findings Are False
John P. A. Ioannidis - 2005


https://journals.plos.org/plosmedic...al.pmed.0020124

There is increasing concern that most current published research findings are false. The probability that a research claim is true may depend on study power and bias, the number of other studies on the same question, and, importantly, the ratio of true to no relationships among the relationships probed in each scientific field...Moreover, for many current scientific fields, claimed research findings may often be simply accurate measures of the prevailing bias. In this essay, I discuss the implications of these problems for the conduct and interpretation of research.

----------

MAY 21, 2021
A new replication crisis: Research that is less likely to be true is cited more


https://phys.org/news/2021-05-repli...true-cited.html

Papers in leading psychology, economic and science journals that fail to replicate and therefore are less likely to be true are often the most cited papers in academic research, according to a new study by the University of California San Diego's Rady School of Management.

In psychology, only 39 percent of the 100 experiments successfully replicated. In economics, 61 percent of the 18 studies replicated as did 62 percent of the 21 studies published in Nature/Science.


----------

Fake (aka "fraudulent") scientific papers are alarmingly common
But new tools show promise in tackling growing symptom of academia’s “publish or perish” culture
9 May 2023


https://www.science.org/content/art...armingly-common

----------

Fake Publications in Biomedical Science: Red-flagging Method Indicates Mass Production
8 May 2023


https://www.medrxiv.org/content/10....5.06.23289563v1

Results: The classification rules using two (three) indicators had sensitivities of 86% (90%) and false alarm rates of 44% (37%). From 2010 to 2020 the RFP rate increased from 16% to 28%. Given the 1.3 million biomedical Scimago-listed publications in 2020, we estimate the scope of >300,000 RFPs annually. Countries with the highest RFP proportion are Russia, Turkey, China, Egypt, and India (39%-48%), with China, in absolute terms, as the largest contributor of all RFPs (55%).

----------

Academy for Science and Freedom presents: The Broken Science Initiative

https://www.youtube.com/watch?v=JLFDjRS_928

https://brokenscience.org/

----------

How Deep Runs The Corruption?
SEP 08, 2023

https://www.zerohedge.com/political...runs-corruption

Intro:

For the past several years, my friends in public health and science have expressed astonishment and professional disorientation at the behavior and messaging of the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH). The scientific journals are part of this.

They simply couldn't believe the brazen manipulation of science for political purposes. They couldn't believe that so many people within these agencies and journals went along with it for reasons of career protection. They've been appalled that science and public health have been deployed in this way.

They worry about the future with this level of corruption. And they've been quite passionate in decrying it, while paying a professional price for not going along.

Implicit in this reaction is a history in which they implicitly trusted these institutions, their data, their reporting, and their sincerity with regard to public health. They presumed that these agencies weren't capable of manipulating science for political reasons. They certainly would never have believed that they would preside over the worst public health calamity of our lifetime.

When they set out to decry this, correct the error, and alert the public to the truth, it wasn't because they hated the NIH and the CDC. Indeed, it was the opposite. They wanted them to be good. They wanted their integrity restored. They wanted to trust again.

In other words, what motivated them is piety in their professions and the agencies that preside over them. In this, the real haters get it all wrong. My friends aren't disinformation spreaders, they're spreaders of facts in the interest of public well-being. They believed strongly that the system isn't broken fundamentally and could be improved.

They decided that they didn't want to practice their craft in an environment of lies. They wanted restoration of truth.

----------

Eisenhower's Less Famous Warning: Government-Controlled Science
by The American Council on Science and Health
26 Dec 2017


https://www.acsh.org/news/2017/12/2...d-science-12219

Among our Trustees is Fred Smith, the founder of Competitive Enterprise Institute (CEI), which promotes the benefits of free markets. I certainly agree with them on that.

At our November meeting Fred asked for a spot on the agenda to talk about how we can better talk about science policy without getting into politics.

That is obviously tricky. Science is both corporate and political, when it comes to basic research the private sector and government fund about half each, so if you defend science you are implicitly defending corporations and engaging in politics.

It wasn't always that way.

[see rest of column at link above]

About the American Council on Science and Health

The American Council on Science and Health is a pro-science, research and education organization operating under Section 501(c)(3) of the Internal Revenue Code. The Council was founded in 1978 by a group of scientists with a singular focus: to publicly support and utilize evidence-based science and medicine and to educate the public by debunking junk science and exaggerated health scares.

Our Mission

ACSH was created to be the science alternative to “news” that is often little more than hype based on exaggerated findings. We help policymakers see past scaremongers and activist groups who have targeted GMOs, vaccines, conventional agriculture, nuclear power, natural gas, and “chemicals,” while peddling health scares and fad diets. We fight back against activists who have attacked the credibility of the overwhelming consensus of academic and private sector scientists who dispute their claims, undermining the integrity of the scientific enterprise.

You may be here because you have decided it's time to fight back. We agree. The Council’s primary aim is to inform the public and policymakers of good science while debunking the junk. We serve as trusted guides in a cultural landscape that too often provides confusing and contradictory information.

We are not a trade association. We do not represent any industry.
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