Currently attending #AAS235 Special Session “Challenges to Astronomy from Satellites”. As someone studying variable and transient phenomena, I care deeply about this issue.
Current talk is from Patricia Cooper (SpaceX) about Starlink.
Cooper: SpaceX is aiming to reach a threshold number of satellites to provide continuous broadband service. Initial estimate of ~1400 satellites over 24 launches to provide “decent” coverage.
Satellites are extra visible between 1-4 months after launch, when they are closely clustered and rise in altitude. #AAS235
They’re testing techniques to darken the satellites but it’s not clear what the timescale is. How many will launch before that technology is applied? #AAS235
Now up is Pat Seitzer from @michiganastro talking about the impact of mega constellations on ground based optical astronomy.
Issues with satellite streaks in your image include loss of information, cross talk in electronics, and ghost images. #AAS235
Starlink constellation currently approved by FCC is 1584 satellites. Seitzer’s models for impact of these satellites are valid for what @VRubinObs (formerly LSST) will observe.
During the entire year, there are significant numbers of bright low orbit Starlinks visible for an hour after start of astronomical twilight in evening and before morning twilight. #AAS235
Seitzer: “cheer up, the worst is get to come”. If the starlink constellation was going to stop at 1584, we could handle it. But there are plans for 10-20 times that, from SpaceX and others. #AAS235
The @VRubinObs (formerly LSST) will be very impacted by Starlink. Original Starlink design will saturate detectors. They are trying to fix this. #AAS235
Ruskin Hartley from international dark sky association: we want satellite visibility to be a rare occurrence. People are excited when the ISS goes overhead. #AAS235
Now up: Harvey Liszt on radio astronomy in a new era of satellite radiocommunication #AAS235
GLONASS and GPS weren’t compliant with agreements regarding frequency band usage until 2007. It took a really long time to get there. #AAS235
NRAO was subject to non disclosure agreements and couldn’t protest publicly regarding Iridium. This damaged radio astronomy community. #AAS235
Iridium is abandoning their radio astronomy protection modes. They are non compliant. #AAS235
User downlink from starlink uses 10.7-12.7 GHz and will have to coordinate with radio astronomy. #AAS235
Fraction of the sky with SpaceX radio interference will be <2% (this is requirement). #AAS235
There are challenges for radio astronomy. Radio astronomy needs to protect allocated bands, locate enough clean spectrum to operate, and deal with quickly changing factors #AAS235
Liszt: “Scientific use of the spectrum requires higher level advocacy than what we have now.” #AAS235
