Discover and read the best of Twitter Threads about #SpaceDebris
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Too close for comfort... 😳
Two large, defunct objects in #LEO narrowly missed each other this morning — an SL-8 rocket body (16511) and Cosmos 2361 (25590) passed by one another at an altitude of 984km. 🚀⚠️ #SpaceDebris
Two large, defunct objects in #LEO narrowly missed each other this morning — an SL-8 rocket body (16511) and Cosmos 2361 (25590) passed by one another at an altitude of 984km. 🚀⚠️ #SpaceDebris
1/ Based on our radar tracking data, we computed a miss distance of only 6 meters with an error margin of only a few tens of meters.
2/ It's important to note that this conjunction occurred in one of the "bad neighborhoods" we've talked about before: 950 - 1050 km. 🏚️
I've been thinking about the new proposed @FCC "five-year rule" for #SpaceDebris mitigation & wanted to share some analysis & thoughts. Whilst I think the intentions are good I believe the implications of the change are poorly understood. Let me explain... [1/n]
As @brianweeden's excellent thread explains, "The new proposed ruling would require all FCC licensed satellites that end their life in LEO to re-enter the atmosphere within 5 years, and ideally ASAP." [2/n]
The justification provided by the @FCC is that "a shorter benchmark would promote a safer orbital debris environment." [3/n]
After 6 years in orbit, we say goodbye to @CopernicusEU #Sentinel1B and thank you to teams here at ESA’s #MissionControl, who for months have worked tirelessly to troubleshoot the issue that has now resulted in end of mission 👉esa.int/Applications/O…
As the first mission of the @CopernicusEU Programme, Sentinel-1 comprises two satellites orbiting 180 degrees apart, providing all-weather, day-and-night imagery of Earth’s surface, designed, built, launched and flown by @ESA.
The partner satellite, Sentinel-1A, remains healthy in orbit, continuing to deliver high-quality radar images for a multitude of applications.
Our focus is on fast-tracking the launch of Sentinel-1C.
Our focus is on fast-tracking the launch of Sentinel-1C.
On Monday, for the first time, we performed a set of manoeuvres to avoid a high-risk collision w. #SpaceDebris created in the #Cosmos1408 anti-satellite test last year.
This was a difficult #CollisionAvoidance manoeuvre.👏👏to our #Sentinel1A Control Team & Space Debris Office
This was a difficult #CollisionAvoidance manoeuvre.👏👏to our #Sentinel1A Control Team & Space Debris Office
#CollisionAvoidance monitoring is unfortunately routine work at #MissionControl, and our teams are well-practiced in reacting to high-risk events.
This near head-on #collision was however unique; the situation evolved rapidly, was tricky to avoid, AND we had <24 hrs warning
This near head-on #collision was however unique; the situation evolved rapidly, was tricky to avoid, AND we had <24 hrs warning
Sentinal-1A, part of the @CopernicusEU Sentinel-1 radar observatory providing day-and-night images of Earth’s surface, had its orbit altered by 140 m in order to prevent collision with a debris fragment ~several cm in diameter
#CollisionAvoidance
#SpaceSwerve
#CollisionAvoidance
#SpaceSwerve
In advance of my monthly analysis of #Starlink conjunction data I wanted to share some additional analysis undertaken over the last few days. It's a work in progress but here's a thread looking a little deeper at the #SpaceX approach to #Starlink orbital space safety [1/n]
#SpaceX provided some relatively detailed information about its approach in a briefing to the #FCC (here: ecfsapi.fcc.gov/file/108107102…) and in an update on the website (here: spacex.com/updates/index.…) [2/n]
#US, #Russia and #China made up for 88 percent of space debris, India among the lowest contributors
businessinsider.in/science/space/…
By @Krittiiii
businessinsider.in/science/space/…
By @Krittiiii
There are 25,182 pieces of space debris in the lower earth orbits, within 2,000 kilometres (km) of earth’s surface, according to the latest issue of Orbital Debris Quarterly News published by #NASA’s Orbital Debris Program Office.
#SpaceDebris
#SpaceDebris
These 25,182 pieces of space debris, include 8,171 active and defunct spacecrafts and 17,011 objects categorised as “spent #rocket bodies and other cataloged debris” as of February 4 of 2022.
#SpaceDebris #NASA
#SpaceDebris #NASA
Maybe I am overthinking this, but it appears to me that all the reporting of the conjunctions involving Starlink satellites & the Chinese Space Station is forgetting that close approaches & avoidance manoeuvres are a normal part of space traffic management.
Even in environments with little to no debris (e.g. in Mars orbit) collision avoidance manoeuvres are performed. Perhaps not routinely, but they do occur.
Even with great surveillance and tracking in the future, and the most robust space traffic regulations, collision avoidance manoeuvres will be part of space operations. Avoidance manoeuvres are unavoidable.
#USSPACECOM deputy cmdr, Lt Gen John Shaw at @ascendspace on Russian DA-ASAT test: We are still characterizing this event. We expect the debris will grow over time. #Perigee, #apogee event will widen. "It will become a threat that we will have to deal with." #ASAT #Russia
Shaw: This isnt' the beginning of such activity. #Russia conducted a similar test in April, though it didn't target a #satellite. Russia is showing "disregard of the sustainability of #space."
Shaw likens tracking objects in #space to book version of #JurassicPark: Scientists had automated sensors to track dinosaurs & algorithm to count the expected number of dinos. Problem is, it didn't account for the population of dinos rising. ...
Here's a thread containing the slides and thoughts I shared at today's @seradata space conference. I wasn't able to invest much time to prepare the talk, so some of the slides will look familiar to those attending April's ESA #SpaceDebris conference. Some are new [1/n]
[alt text: talk title "The Space Debris Environment - Current Status and Evolution of the Risk"]
I put this slide together using data from celestrak.com. It shows the historical evolution of the orbital object population (as recorded in the public catalogue). The highlight statistic is that active spacecraft make up 20% of the current catalogue population [2/n]
Livetweeting today's @SWFoundation Summit for Space Sustainability, using the hashtag #SWFSummit21
From @WaleedCandC: When looking at #ClimateChange the space-based EO perspective provides us:
-the global scale-view of climate change
-data to inform the implications of our actions
-tools to improve our models so we can better prepare for & mitigate changes. #SWFSummit21
-the global scale-view of climate change
-data to inform the implications of our actions
-tools to improve our models so we can better prepare for & mitigate changes. #SWFSummit21
Thelma Krug, Vice-Chair of the @IPCC_CH:
Remotely sensed data reduces our uncertainties in knowing our "energy budget" & "sea level budget," as well as better predict future conditions.
Remotely sensed data boosts re-analysis, homogeneity & continuity of datasets. #SWFSummit21
Remotely sensed data reduces our uncertainties in knowing our "energy budget" & "sea level budget," as well as better predict future conditions.
Remotely sensed data boosts re-analysis, homogeneity & continuity of datasets. #SWFSummit21
I think the #KesslerSyndrome is too often presented as a tipping point or a threshold we have yet to cross, so I wanted to use some aspects of my paper at the 8th European Conference on #SpaceDebris to explain why I think that is wrong [1/n]
The starting point of my thinking was to look at how natural populations grow. The simple exponential model is a standard model that describes the growth of a single population [2/n]
If we know the initial number of individuals in the population N(0) then this model allows us to estimate the number of individuals at any future time t. Here, r is the intrinsic rate of natural increase, which depends on the birth rate, b, and death rate, d [3/n]
I am seeing some ill-informed takes on today's near-miss in orbit so would like to offer some trajectory corrections if I may. Firstly, the chance that a single collision would trigger a catastrophic 'chain reaction' that would sweep through LEO is tiny.
For every close pass involving catalogued objects in orbit we can estimate a collision probability, or Pc. The Pc is between 0 and 1. If it is 1 we can say that a collision is certain. If it is 0 then we can say that a miss is certain.
The event today may have had a Pc between 0.02 & 0.2. In any case, the Pc was relatively small (compared to a Pc of 1) so a miss was the most likely outcome. For a chain reaction to occur a long & sustained sequence of collisions would need to take place.
🇪🇺#EUSST contributes to protecting the safety & security of European economies, societies & citizens.
Our Operations Centres are monitoring a potential collision of two large, inactive #space objects. EU #SST estimates a probability above 1% that they may collide in two days👇
Our Operations Centres are monitoring a potential collision of two large, inactive #space objects. EU #SST estimates a probability above 1% that they may collide in two days👇
The two defunct objects are OPS 6182 (1978-042A), a meteorological #satellite🌧️🛰️ and rocket body🚀 SL-8 R/B (1981-041B). The network of EU #SST sensors📡 has been requested to observe the objects and provide additional measurements.
Stay tuned here for more updates.
#spacedebris
Stay tuned here for more updates.
#spacedebris
In the last #SOCRATES report of 2020 #Starlink satellites accounted for 29.1% (1-in-3.4) of all 44,530 close approaches < 5 km recorded for the first week of January 2021 with a total Pc of 1.7% #SpaceDebris
Ignoring Starlink-on-Starlink conjunctions the constellation satellites accounted for 9.8% of all close approaches < 5 km.
The yearly rates based on this report are 675,451 close approaches < 5 km involving #Starlink (227,655 ignoring Starlink-on-Starlink conjunctions)
ESA's #missioncontrol centre is preparing for the launch of #Sentinel6 on 10 Nov.
In particular, teams are rehearsing the 'Launch and Early Orbit Phase' – the riskiest period in the fledgling spacecraft's life
Find out more🛰️👉esa.int/Enabling_Suppo…
In particular, teams are rehearsing the 'Launch and Early Orbit Phase' – the riskiest period in the fledgling spacecraft's life
Find out more🛰️👉esa.int/Enabling_Suppo…
Like a bird hatching from the egg, this is the period in which a new spacecraft unfurls its solar arrays, wakes up to test its core functioning and manoeuvres into the correct path, all the while at its most vulnerable to the hazards of space.
#Sentinel6
#Sentinel6
The @CopernicusEU #Sentinel6 Michael Freilich satellite will ensure the 'continuity of service’ of the Jason missions currently providing data on Earth’s changing oceans, but reaching the end of their lives.
Another thread about sat collision probability 🛰️💥🛰️
This time let's talk about regulations, as the FCC has just solicited input about how to regulate collision risk
As we know, risk can be computed as = 1-(1-Pc)^N
where Pc = each sat's collision probability and N = # of sats
This time let's talk about regulations, as the FCC has just solicited input about how to regulate collision risk
As we know, risk can be computed as = 1-(1-Pc)^N
where Pc = each sat's collision probability and N = # of sats
Now, you don't have to be a math expert to know which variable is most important in that equation. Yep, the exponent!
Say you've been offered X^Y dollars, where each variable is between 1-9 and you get to choose one of them. You'd choose Y every time! Who cares what X is? 💵💰💵
Say you've been offered X^Y dollars, where each variable is between 1-9 and you get to choose one of them. You'd choose Y every time! Who cares what X is? 💵💰💵
Surprisingly, the FCC has asked if they should regulate risk by only limiting Pc, or if they should also take into consideration the N part of the equation.
Isn't the math obvious? Why would anyone ignore the most important part of the equation?
Well, it makes it hard to comply
Isn't the math obvious? Why would anyone ignore the most important part of the equation?
Well, it makes it hard to comply
I put this #orbit visualisation tool together in #Excel to help with teaching & I'm really pleased with how it turned out. 3D rendering & real-time/instant updates via a control panel without any complicated code. It should run on any PC or laptop. A few minor bugs to fix.
P.S. I'm happy to share (*also for beta testing*) if anyone is interested. Please just send me a DM with your email address. It's a 2 MB macro-enabled Excel spreadsheet (tagging the #spacedebris tweeps too)
P.P.S. My DMs are not open (sorry!) so we will need to follow each other if you would like to send me your contact email. Or you can find mine online...
Here is a thread-based version of my talk at the @AeroSociety conference on 'Safeguarding Earth's Space Environment' that I hope gets some key points across about modelling #spacedebris & how it can help to identify the data we need to understand #SpaceSustainability (1/n)
Caveat: I use images as metaphors, to help with understanding of key concepts, so my slides have no words in them. (2/n)
Our models have two distinct roles: PREDICTION and UNDERSTANDING. Understanding can help us to design better models and gather more relevant data. Both of these roles are important in relation to #SST, #SpaceSafety and #SpaceSustainability (3/n)
Observations & model of daily count of close approaches in orbit involving #Starlink satellites from 1 October 2019 to 31 August 2020. Close approaches shown exclude Starlink-on-Starlink events for miss distances of < 5 km and < 1 km. Data from SOCRATES #spacedebris
Over the period: Starlink satellites were deployed at a rate of 1.81 per day. Each Starlink satellite deployed in orbit adds 0.48 conjunctions per day < 5 km.
14.6% of all close approaches - about 1-in-7 - of the 37,910 events in the 31 August 2020 SOCRATES report involved Starlink. This proportion includes Starlink-on-Starlink close approaches.
In this extract from the @SpaceX response to the @FCC there is a calculation that might be relevant if satellites were molecules in an ideal gas (or perhaps if addressing risks from small #spacedebris) but is not appropriate when considering large objects or constellations.
This highlights a lack of #spacedebris expertise & experience, and reliance on a model (DAS) that is not understood.
As the analysis of SOCRATES data has indicated, the reality is very, very different from what @SpaceX is expecting. Satellites are not randomly distributed around the Earth and are not travelling in random directions.
New response to @FCC by @SpaceX identifies probability of #Starlink collision with large #spacedebris is 8E-5. Single conjunction event < 0.5 km on 2 July with SL-3 R/B predicted by SOCRATES on 30 June 2020 had max. probability of 3.5E-5 (dilution thresh: 0.169)
Another event in the same SOCRATES report predicted miss of 172 m on 30 June with 3CAT-2 & max. probability of 1.39E-4 (dilution threshold: 0.044).
I realise that I am quite likely comparing apples & oranges here, but that's also one of the points I am trying to make.
In 2019 I presented a paper at the 1st International Orbital Debris Conference looking at implications of relocating satellites of a large constellation from high LEO altitudes to low LEO altitudes (hou.usra.edu/meetings/orbit…). Here's a thread on some new analysis #spacedebris 1/n
In my presentation I pointed out that relocating satellites to lower altitudes might solve long-term space debris issues but wouldn't be risk-free & could introduce problems related to space safety. Adding traffic to an already busy region could increase conjunction events (2/n)
Space systems at altitudes below 600 km are typically small satellites such as cubesats. Often these do not have a propulsion capability and so cannot implement collision avoidance manoeuvres. The figure shows recent launch activity & spatial density (data courtesy of @ESA) (3/n)
Yesterday 15:53 UT, the #ISS had to make an emergency manoeuvre to dodge a piece of #spacedebris.
My analysis suggests it was object 27923 (1987-079AG), a piace of debris from a Proton rocket stage. It would have passed close to the ISS at 18:28:09 UT
@SSC_NL (corrected repost)
My analysis suggests it was object 27923 (1987-079AG), a piace of debris from a Proton rocket stage. It would have passed close to the ISS at 18:28:09 UT
@SSC_NL (corrected repost)
2/2
The nominal miss-distance would have been ~0.5 km at 18:28:09 UT, but that has a +- of at least 1 km.
This debris piece of the Proton rocket that launched Komsos 1883 in 1987 is of 'medium' size according to CSpOC ('medium' = RCS 01.-1.0 m^2)
The nominal miss-distance would have been ~0.5 km at 18:28:09 UT, but that has a +- of at least 1 km.
This debris piece of the Proton rocket that launched Komsos 1883 in 1987 is of 'medium' size according to CSpOC ('medium' = RCS 01.-1.0 m^2)
*Kosmos, not 'komsos', grrrr!!!!!
Excellent piece by @moribajah that highlights some of the key challenges to #SpaceSustainability & #spacedebris mitigation.
For many aspects of spaceflight we can test (verify) compliance with a set of requirements before the spacecraft is launched. Will the thermal control system work? Will the solar arrays deploy? For compliance with #spacedebris rules/requirements we have to wait until after launch
We don't yet have the systems or the data needed to do this accurately or consistently across near-Earth space, and we don't yet have the understanding to do this fairly, in a way that encourages compliance without creating obstacles to sustainable development. Work still to do.
