🧵 I'm sure you've heard of the "space debris crisis". We knew about it in the late '70s + by the early '00s we had a robust set of laws that established the 25yr rule, required operators to design craft to withstand minor collision + to minimise the odds of in-orbit explosion...
It's fascinating that even in the time I have read about it we have learned so much about the problem, though often we only find it turns out more difficult than previously thought 😕

Pre-Kessler it was thought "natural removal" (i.e. orbit decay) would take care of most...
By 2005, when I first heard about the problem from an @esa article, we were speaking mostly about RB explosions from leftover fuel in orbit, and from objects breakups that occurred over time due to expected degradation of materials.

In the last few years the problem has been done great justice by some fantastic journalists + science communicators.

It is because of that effort that I can confidently say something like "I'm sure you've heard of the space debris crisis" to nearly any person I meet nowadays 📰
A tiny aside, some recent examples (great reads even for those familiar):

- bloomberg.com/opinion/articl…

- newyorker.com/magazine/2020/… (animated page, sometimes slow)
People get that space debris is a problem and that we haven't yet developed a [reliable] on-orbit removal solution [to scale or maturity].

But where my work lives is even before that: to catch debris—or to prevent debris in the first place—you have to know WHERE it is.
Know its trajectory, speed, size, etc. So you can know where it's going when you want to catch it, or whether it's going to hit something else + shatter. You have to know this for _everything_ up there.

SO much hard work is going into debris removal, but STM comes first 🛰
Space Traffic Management (synonymous w/ Space Situational/Domain Awareness to some) is about cataloguing everything that is up there, it's physical + orbital properties, + updating it as often as possible. Accurately + precisely.

This is only possible through global cooperation.
Like @RDEIL was speaking about earlier, this global sat-tracking effort began with the US MiniTrack network in the '50s. But the need for co-op isn't just that no country has can see our whole sky; it's also bolstering an inexact process through correlation with multiple methods.
The Earth gets brighter + noisier as our sats get smaller.

Every optical/radio/radar sensor is prone to some noise/error, digitisation of this analog data inevitably loses information, + the process by which trajectories are propagated can only be simulated to limited precision.
In my work, I think of these as a cycle:

1. Data acquisition: a sensor records the sky.
2. Processing: analog signals are digitised, data is calibrated to make the relative absolute, etc.
3. Interpretation: system(s) seeks to identify objects in the data, infer their properties.
4. Propagation: known algorithms (e.g. SGP4) estimate orbital perturbation effects on the current trajectory and plot the likely path of the identified object in the near future.
5. Planning: take the knowledge you have now, decide where to point your sensor next.
With these steps defined, and looking from a computer science perspective, it is unsurprising that each of these suffer unique issues that can contribute to the errors we see.

(See: incident last Oct. where <STM startup> put up a collision alert + Vandenburg was like "nah, m8")

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More from @People_Of_Space

1 May
Grote Reber (the inventor of the radio telescope) moved to TAS in the 1950s + spent the rest of his life here, after recognising conditions ideal for his work.

A high Southern latitude, where the ionosphere tends to be thinner, w/ a distinct lack of terrestrial RF interference. Colour-enhanced photograph: a wide-angle shot of a large sno
.@UTAS_ operates a buncha telescopes in picturesque locations across the state, both radio + optical, but there is also a big independent/hobbyist community here.
Astrophotography 📸✨ is a hit here due to our lack of light pollution, and we also get the 🌌 Aurora Chasers 🌌 A large radio telescope sits on a green hill surrounded by gA map with overlay shows light pollution levels around Tasma
📷 credit: @PhilKitt (who does some seriously great work in Tassie)
Read 5 tweets
1 May
Hello everyone 👋 I'm Mars (@TheMartianLife) and I am your host for this week.

A quick intro: I am a PhD candidate at @UTAS_/@CSIRO working on using Machine Learning to improve tracking precision and reliability for satellites and space debris.
Before this, I had never worked in space before (though I was a BIG enthusiast); I actually came from computer science, where I have worked on ML for a range of other domains.

Needless to say, I am very excited to be able to combine the two. And for such an important issue 📡~🛰
And I'm from Tasmania. Over here at UTC+10 and down here at 42°S it's just gone 6am Sunday and it is still pitch black as we're coming into our short Winter days.

...so forgive me if I start a bit slow this morning 😆 Screenshot: Google Maps, with Tasmania searched. The result
Read 4 tweets
20 Feb
So a final thread from me as your host today: some top tips on how to write for a popular audience about complicated subjects #space #science #writing #storytelling
The essence of any good communication is simplicity. It’s the same in print, television, radio, online, or attaching notes to carrier pigeon’s legs.
In the sixties, a Granada current affairs show set the template for using a visual medium more effective: it was pioneered by a remarkable fellow called Tim Hewat, a flavour of whose personality is here: theguardian.com/news/2004/dec/…
Read 47 tweets
20 Feb
So for my final half day, I wanted to share some "top tips" on writing for a popular audience - especially about space, and I already collected some thoughts here, but will now take the opportunity to expand on them where I can twitter.com/i/events/12229…
Before I begin, I will obviously refer to Dick Feynman a great deal, because as I explained, quite by accident I came into his orbit and Al Hibbs, both of whom knew how to explain things
In 1981, Chris Sykes literally pointed a camera at Feynman and let him talk. Fifty minutes of utterly compelling television. And here is the story behind that.
Read 20 tweets
19 Feb
So my final thread on this last full day of tweeting - and my God what a day for anyone who is interested in .... checks notes.... Mars. What I wanted to do is make a few points about journalism .... and in particular, people who write about space #Mars #JournalismIsNotACrime
To set some context, then, what exactly is a “space journalist”? It is an interesting question and one which is fairly easy to answer. As a journalist, your function is to report what happened and also why.
In that last photo, the bearded fellow at far right was one of the most extraordinary space reporters I ever met - and I was just out of shot when that picture was taken btw. Jonathan Eberhardt was an award-winning reporter -- washingtonpost.com/archive/local/…
Read 19 tweets
19 Feb
So as I suspected I would be exhausted today, being an industrious sort of fellow, I had prepared some tweets ahead of time if #Perseverance hadn't worked........ but with a little tweaking, still relevant #countdowntomars

As everyone who follows space knows, there is a narrow line between success and failure - and there but for the grace of God.......telegraph.co.uk/news/2021/02/1…
As many of you know, the British tend to celebrate failures and heroic ones at that..... newstatesman.com/culture/books/…
Read 30 tweets

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