First up this morning is Anne Bennett from CCAR, now talking about identifying and assessing debris strikes in NASA spacecraft telemetry #orbitaldebris2019#spacedebris
The work uses changes in spacecraft angular momentum. The spacecraft corrects for the torque resulting from an impact and the delta-H is detected and used to identify a strike
Need to filter out anything that is not a debris strike (slews, thruster firings) and any gradual changes in angular momentum
For a single spacecraft in GEO, the algorithm detects several impacts each day (up to 30 or 40 at most). Possible micrometeoroid impacts but delta-H is quite high for some. There are also some temporal patterns.
MMS data: 4 spacecraft in formation, 300 days in 2016. Known debris strike in this period but this single event is "overwhelmed" by other detections. Also some "mystery" repeated torques observed, probably mission related.
Detection methods do accurately identify momentum changes. Small detections may be noise but they repeat on yearly basis so some doubts remain. Algorithms permit any spacecraft to become an in-situ debris detector (depending on telemetry differences)
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Welcome to this month's look at #Starlink conjunction risk mitigation manoeuvres. Through 30 April 2023, I estimate that Starlink satellites have made a total of > 45,000 manoeuvres to mitigate the risk of colliding with other space objects [1/n]
A better relationship to consider is the one between the (cumulative) number of manoeuvres and the (cumulative) number of Starlink satellites launched. The growth is a non-linear function of the number of Starlink satellites [2/n]
Here, I looked at the manoeuvre estimates/reports in 6-monthly intervals, corresponding to the reporting periods used by SpaceX. Additionally, I added a prediction to the end of 2024 based on an exponential fit through 30 April 2023. [3/n]
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]
Latest analysis for #Starlink & #OneWeb shows these two constellations accounted for 42% of all close approaches within 5 km predicted by #SOCRATES at the end of August, with Starlink alone accounting for 29%. [1/n]
On average, #SOCRATES predicts that each #Starlink satellite will now experience 1 close approach within 5 km with a non-Starlink object every day, and each #OneWeb satellite will experience 3.4 close approaches with a non-OneWeb object every day. These rates are increasing [2/n]
Here's the same data from [2/n] plotted with respect to the number of satellites in each constellation in orbit, clearly showing #SOCRATES predicts that #OneWeb satellites experience more close approaches (within 5 km) per satellite than the #Starlink satellites [3/n]
A follow-on from yesterday's thread with a note about averages. In a #SOCRATES report from 30 June 2022 the average collision probability for each #Starlink conjunction was 3.7E-6 but the range of values can be broad (chart shows data since 2019) [1/n]
#SOCRATES predicted some events with a collision probability > 1E-2 (1-in-100) & some with a probability < 1E-7 (1-in-10,000,000). The average value might seem to be almost negligible & you might think all conjunctions would be similar, but that's not the case [2/n]
In addition, some #Starlink & #OneWeb satellites experience more conjunctions than others. Most satellites experience relatively few encounters but a few satellites are involved in a relatively large number (charts shows data for 7 days from 30 June 2022) [3/n]
Welcome to my (delayed) monthly analysis of @CelesTrak#SOCRATES conjunctions. Since 1 March 2019, SOCRATES has predicted about 9 million unique conjunctions within 5 km involving active or derelict payloads. This is a thread focused on those involving #OneWeb & #Starlink [1/n]
#OneWeb payloads have accounted for ~500,000 unique conjunction predictions since 1 March 2019 (5.5% of all predictions made), while #Starlink payloads have accounted for ~1.1 million (12.5%) [2/n]
On 1 March 2019 #SOCRATES predicted ~3860 unique conjunctions within 5 km. On 30 June 2022 the corresponding number was ~10,160, an increase of ~160%. #Starlink accounted for ~2570 (25%) & #OneWeb accounted for ~1250 (12%) [3/n]
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]
My focus has mostly been on understanding the implications relating to the choice of the probability threshold for collision avoidance manoeuvres. With the #SOCRATES#Starlink data now running across nearly 3 years we can gain some insights that may be useful [3/n]