4 September 2019 at 7:29 pm #574391Nick JamesParticipant
In another example of the impact of the SpaceX Starlink constellation, ESA has just announced that they had to perform an avoidance manoeuvre of their Aeolus satellite as a result of an unacceptably high probability of a collision with one of the Starlink spacecraft. It sounds as though this was not very well handled by SpaceX and this is when they only have 60 spacecraft on orbit. The next batch of 60 is due for launch in October with almost monthly launches thereafter. SpaceX hope to have 2,210 satellites in orbit by 2024 March.5 September 2019 at 11:32 am #581338Neil MorrisonParticipant
Putting a very jaundiced spin on the developing situation it may be said that Star ,link is a case of pressing ahead for financial gain irrespective of the consequences to others.12 December 2019 at 8:28 pm #581771
I don’t know about the credentials of this news source. But it looks like SpaceX may be testing ways of reducing the reflectivity of the Starlink satellites.13 December 2019 at 2:33 am #581772Grant PrivettParticipant
Even if they push the albedo from (say) 70% to 10% thats only going to be 2 and a bit magnitudes, so you go from a 3rd mag satellite mucking up your images to a 5th mag. Great.
Given that even geosats mess up deep sky images (and they are normally 8th mag or fainter) I’m not seeing much benefit.
The problem is he has a business plan to make money. What is his incentive to stop?
If we said anything, I wonder what he would call us?13 December 2019 at 5:54 am #581773
Good point, Grant.
On the other thing – I’m sure he’s learned his lesson, notwithstanding the outcome of the case.13 December 2019 at 6:59 am #581774Nick JamesParticipant
You’re right, but two mags is quite a lot. I doubt if it would be anywhere near that and would only apply to satellites under control since it is on only one face. Since quite a few are tumbling already it may not be very effective. From our point of view I think we will become more dependent on large numbers of short exposures and clever stacking software. CMOS cameras have come along at just the right time.13 December 2019 at 9:51 am #581775
VS observers such as myself are relatively fortunate. We already have to deal with satellite trails and cosmic ray hits but, as long as they don’t lie within the apertures around the VS and comparison stars, they don’t matter.
Those interested in precision astrometry — of asteroids and comets, for example — are in a similar position.
It’s the takers of pretty pictures who will have the real difficulties.
Perhaps more people will become interested in the measurement of images rather than in imaging per se. I’d argue that the former is more scientifically valuable but I’m a scientist and so can be expected to be biased.13 December 2019 at 10:41 am #581776
No doubt the data scientists at the LSST who are developing methods for transient discovery and monitoring are all over this issue.13 December 2019 at 4:40 pm #581777
I’m on their mailing list. They appear to have mitigating procedures under development.
AFAICT, they would prefer not to have to deal with it but they are prepared to do so.
One approach is that each field is imaged in several filters. A satellite will have moved between successive images, so a transient still stands an excellent chance of being detected. A problem, as I understand it, is that the calibration images (i.e. those without transients) will require much more care in their preparation.13 December 2019 at 4:45 pm #581778
A NEO will also move during and between exposures but very likely nowhere as quickly and certainly nowhere nearly as bright. Both characteristics are easy to determine in software.13 December 2019 at 6:07 pm #581779
Thanks for the info. I read about the project with great interest. On my Twitter account (astro only, no craziness) I’m always retweeting the LSST news feeds to excite my followers about the project.
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