https://solarsystem.video/videos/watch/513607ee-8c6d-47e4-92eb-c0eb43a36c60 03:14 Astronomers for Planet Earth by Leonard Burtscher 26:07 Impact of LEO Satellite Constellations on Astronomy and the Environment by Ronald Drimmel 51:37 The Critical Satellite Threshold for Viable Astronomy (in the optical / visible) by Olivier Hainaut 01:01:11 Q&A / discussion Collected links: https://planet4589.org/space/stats/acdec.html https://www.nature.com/articles/s41586-025-09759-5 https://spacenews.com/it-is-time-to-take-astronomy-off-earth/ https://www.eso.org/public/unitedkingdom/news/eso2607/?lang and https://www.eso.org/public/archives/releases/sciencepapers/eso2607/eso2607a.pdf https://thefutureofmeetings.wordpress.com The lively chat: Collected links: Https://planet4589.org/space/stats/acdec.html https://www.nature.com/articles/s41586-025-09759-5 https://spacenews.com/it-is-time-to-take-astronomy-off-earth/ https://www.eso.org/public/unitedkingdom/news/eso2607/?lang and https://www.eso.org/public/archives/releases/sciencepapers/eso2607/eso2607a.pdf https://thefutureofmeetings.wordpress.com 00:41:14 Jan-Peter Muller: What about green hydrogen as a replacement for kerosene? 00:51:31 Leonard Burtscher: Hydrogen itself is very complicated to handle and doesn’t have the energy density needed to power airplanes. You probably need to process it further and produce synthetic jet fuel. This will probably be the route to decarbonise air travel, but it will require tremendous amounts of energy: to power the planes leaving Germany you need as much electrical energy as all of Germany uses now (~600 TWh). 00:55:07 Jan-Peter Muller: ESA have a green hydrogen programme which is predicated on the use of green hydrogen to power heavy transportation and aircraft. I am involved in one of the projects to stop solar power wastage due to issues with the power grid being based on coal+nuclear. It would be interesting to have you involved in a future debate on this topic. 00:58:14 Leonard Burtscher: Happy to comment on this. Note, however, that „solar power wastage“ is not really a problem: We currently „waste“ 3% or so of renewable power (i.e. cannot use it because grids are full or demand is lower than production). This will be solved very soon with batteries — and it is OK to throw away a small part of electricity during max. production hours in order to save on grid expansion. 01:31:10 Leonard Burtscher: @Jan-Peter Muller (and everyone!) Happy to continue the discussion! Contact me via leo@a4e.org 00:41:56 Güray Hatipoğlu: We actually did a lot of VR in pandemic times, as we of course I am talking about regular people in general, it was interesting but a sad experience. Though virtual poster presentation as a 2D MMORPG like game was awesome. 00:43:05 Nimisha Verma: Isnt moving to VR worldwide just a different way of produce waste? With the way technology is moving, wouldn't it just create a different way of producing pollution rather than reducing it? 00:44:11 Güray Hatipoğlu: do you think this for also just virtual meeting, not with VR googles gadgets, just like playing a game on PC? 00:44:57 Maarten Roos-Serote: It would be important to estimate the CO2 / pollution for a typical conference ran in VR 00:45:15 Nadia Poddighe: I suppose this would require people to understand you need one device only to do simple meetings. I mean, it can't become a trend like phones or whatnot. 00:47:10 Nimisha Verma: True, but more often than not, we see technology becoming a trend rather than solution. If we do implement something similar to solution is quite a nice idea. But more often than not, given how much technological waste is produced in developed countries and being shipped to developing or underdeveloped countries is a big concern for now. 00:47:39 Maarten Roos-Serote: Just to add music and art to Pale Blue Dot and Carl Sagan, check this out from Nightwish (Finland): https://www.nightwish.com/songs/all-the-works-of-nature-which-adorn-the-world-ad-astra 00:48:12 Güray Hatipoğlu: Reacted to "Just to add music and art to Pale Blue Dot and Carl Sagan, check this out from Nightwish (Finland): https://www.nightwish.com/songs/all-the-works-of-nature-which-adorn-the-world-ad-astra" with 💾 00:49:55 Nadia Poddighe: I get you and it is a real concern. Though I believe everything depends on strong demand by users so again I feel that education stands at the base of everything we do. I guess that's another of our role as scientists? 00:51:39 Leonard Burtscher: Reacted to "We actually did a lot of VR in pandemic times" with 👍🏻 00:53:14 Nimisha Verma: 😅 I may be a pessimist in this regard but I feel even though we play a significant role in that part, more often than not, our role is very much diminished by the present political scenario. We are very much dependent on that and that is a very sad part. Influential scientists seperate from political pressure are far and few. 00:55:04 Tanja Michalik: Is it 10 000 oder 100 000? 00:55:05 Leonard Burtscher: Yes, (electronic) waste is a problem and we also need to embrace circular economy approaches much more. But if you look into the environmental footprint of VR conferences vs. real conferences you will certainly also find that real conferences have a much greater environmental impact. If organised cleverly, a couple VR headsets could be used by an entire institute and replace hundreds of flights over many years. 00:58:40 Nadia Poddighe: Unfortunately, I share this feeling. Although I think now more than ever it's crucial to put the good info out there. I think many scientists would like to cooperate to inform people, too. It's frustrating, I know, as it is frustrating to think we see cuts on telescopes and other essential stuff in our field, but there isn't any will to reduce truly futile productions in other environments. Though we can still make an impact. 01:00:23 Maarten Roos-Serote: Https://planet4589.org/space/stats/acdec.html 01:00:36 Güray Hatipoğlu: Reacted to "Https://planet4589.org/space/stats/acdec.html" with ❤️ 01:00:58 Nadia Poddighe: Reacted to "Happy to comment o..." with ❤️ 01:01:41 Nimisha Verma: For the no of satellites - Do people really not learn from movies like Wall-E? It is not just for fun. 01:02:36 Maarten Roos-Serote: Hmmm, Money speaks louder? 01:03:33 Nimisha Verma: Certainly. And the irony is that scientists are not paid enough anyway. Atleast at PhD level, I donno about higher ups.😅 01:06:01 Leonard Burtscher:I presume these folks haven’t read this Nature article… https://spacenews.com/it-is-time-to-take-astronomy-off-earth/ 01:08:27 Luiza Frenkle: That image is terrifying 01:09:00 Leonard Burtscher: Thanks for the talk, Ronald! Can you comment on the orbital data center and solar energy from space „business cases“? I simply don’t understand how they can be profitable. Would powerful CPUs/GPUs even survive in the space environment? Can solar power from space be cheaper than batteries which are now at 1 ct/kWh of storage cost (and solar power from space doesn’t work when it’s cloudy either…). 01:20:33 Güray Hatipoğlu: Would not Dark satellites still pass over the line of sight of many objects though? Are they fast enough to only cause minimal change in the lightcurve? 01:27:39 Olivier Hainaut: The eclipse is < milisecond - negligible... It will cause a dip < 0.001mag on a 1s exposure; smaller for longer exposure 01:23:36 Leonard Burtscher: @Olivier Hainaut – are you in touch with the ESO Supernova to visualise this loss of night sky? I am sure lots of planetaria worldwide would be „happy“ to show this! 01:28:04 Olivier Hainaut: yep, I'm at ESO and I work in close collaboration with ESO communication 01:25:28 Nadia Poddighe: What's the purpose of having the night sky so bright? As far as I understand, darkness is an "extra perk", meaning it costs more to producers to produce dark satellites. Though some companies made it clear that night sky brightness was one of their main goals and I fail to understand why? 01:29:27 Olivier Hainaut: To make the sky bright is a side effect they neglected... They want to illuminate the ground [but I don't understand the economics or even the usefulness] 01:31:31 Teodora Žižak: It seems to me it's a matter of luxury and convenience. People willing to pay a certain amount will be able to turn night into day for their own pleasure. 01:33:43 Leonard Burtscher: In case you want to know more about state-of-the art VR science conferences, please check out this group: https://thefutureofmeetings.wordpress.com 01:36:12 Teodora Žižak: Excellent point, Olivier! 01:40:24 Leonard Burtscher: We tried to convince IAU and others to make meetings fully virtual… So far with limited success. [Die vollständige Nachricht kann in dieser Version nicht angezeigt werden] 01:42:54 francisco diego: Properly enforced regulations are essential. Programs must be approved and regulated by qualified international panels. Programs will come from many countries and enterprises and need to be coordinated. All aspects of the programs must be considered. Is the program really needed? What are the impacts? Benefits vs disavantages. What is the life time? What are the plans for the end of life? An updated version of the UN Outer Space Treaty. If the whole adventure is to be driven by commercial interests, operating with absolute impunity, the world is doomed. 01:44:07 francisco diego: Yes, planetary defense! in this case Earth defense. 01:47:45 Olivier Hainaut: My next meeting is coming up - I need to go. @Europlanet thanks for the invitation. @everyone: if you want more info on what we do, go to eso.org 01:47:58 Tanja Michalik: I don't think the people in power across the world will care about the right for a dark sky, unfortunately 😦 01:48:03 Andjelka Kovacevic: Thank you so much for great webinar! 01:48:13 Amy Riches: Informative sets of data + models, and discussion, for these areas of significant challenge. 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