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The disappearance of Gaia, ESA spacecraft will be turned off on 27 March 2025
- margalabargala 2y agoAbsent from that link but important context: The reason why they are actively shutting it down, is that they are running low on fuel, and want to ensure that the spacecraft does not litter important orbital locations. Gaia has spent its life at Earth's L2 Lagrange point, which is a valuable and limited area of space; they do not want to have to plan around dead spacecraft in future missions. Thus, before the spacecraft runs out of fuel, they have moved it away from L2 into its final graveyard orbit. It is not capable of performing the science for which it was designed in its graveyard orbit.
- 8bitsrule 2y agoThanks. That page also helped me find one that sums up the mission so far, and explains what's to come in 2026 & 2023. https://www.esa.int/Science_Exploration/Space_Science/Gaia/Last_starlight_for_ground-breaking_Gaia https://www.esa.int/Science_Exploration/Space_Science/Gaia/L...
- normie3000 2y ago> what's to come in 2026 & 2023 Weird, I checked the link but there's no mention of time travel.
- pinkmuffinere 2y agoThe time travel discussion is on the 2028 page, but intentionally absent from the 2025 page to minimize risks of contamination.
- 8bitsrule 2y agoI guess you didn't read to the line where it says > two massive data releases are tabled for around 2026 and the end of this decade, respectively.
- alfiedotwtf 2y agoOh?! I was always under the impression that Lagrange points were convenient calculation spots where everything sums out, but from what you’re saying, it’s a deep gravity well? Mind blown! Edit: don’t mind me, I was completely off… thanks ChatGPT!
- dmoy 2y agoL4 and L5 are more stable. L2 isn't super stable, hence the need for fuel for station keeping. More polite to vacate on purpose rather than just erratically bounce around a nearby orbit after fuel runs out. Idk if I'd describe any of them as "deep gravity well"
- margalabargala 2y agoIt's not a deep gravity well, it's a fairly weak gravity well, but with fuel one can orbit L2 reliably. Without fuel, one can orbit L2 erratically. People with the ability to send satellites places, don't like sending expensive satellites to places with large bodies in erratic orbits.
- JumpCrisscross 2y ago> Without fuel, one can orbit L2 erratically It takes an infintessimal amount of energy to detatch something from L2.
- margalabargala 2y agoSure, you won't be at L2, but you may remain near L2 for some time.
- numpad0 2y agoWhere everything sums out is a completely flat spot on a table, it won't hold a freely moving object. Lagrange points are more like shallow dents that tend to attract rolling marbles.
- perihelions 2y ago- "Earth's L2 Lagrange point, which is a valuable and limited area of space" That's a strong exaggeration; it's millions of km across in three dimensions. Gaia's orbit alone is - "263 000 x 707 000 x 370 000 km, 180 day-long orbit around L2" https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_enters_its_operational_orbit https://www.esa.int/Science_Exploration/Space_Science/Gaia/G...
- echoangle 2y agoL2 is also said to be unstable, but I don't know how long it would take for Gaia to move far away enough that the collision risk would be negligible.
- perihelions 2y agoThe issue with that is things that naturally escape from Lagrange points often crash into the Earth, which is one of the risks they're trying to mitigate.
- happyopossum 2y agoIf by “crash into earth” you mean “burn up harmlessly in the upper atmosphere” then ok - but it kinda sounds like that’s not what you’re claiming…
- perihelions 2y agoPieces of spacecraft often survive atmospheric reentry.
- tgsovlerkhgsel 2y agoI understood why they are shooting it into a graveyard orbit, but not why they're actively turning it off rather than trying to get whatever science they can out of it. (I'm sure that if I have a basic idea like this, the people at ESA also had it, but I haven't seen the reasoning explained anywhere.) I think this part of the Wikipedia article answers it: > In order to maintain the fine pointing to focus on stars many light years away, the only moving parts are actuators to align the mirrors and the valves to fire the thrusters. It has no reaction wheels or gyroscopes. So without "fuel" (reaction mass/gas) for the cold gas thrusters, it likely couldn't hold a stable attitude, and a tumbling spacecraft is likely quite useless because you can't even properly communicate with it, let alone use instruments. I wonder what considerations went into not attempting to use it as a low-value probe sending out telemetry using a low bandwidth omnidirectional antenna (which I would expect the spacecraft to have for recovery in case something goes wrong). Maybe we already have all the science that would be interesting from other probes, maybe management/budget decisions, maybe it wouldn't work, but it would be interesting to see the decision making.
- Facemelters 2y agoCosts money to support the mission
- tekla 2y agoThe DSN is already strained
- randoomed 2y agoESA is actively trying to reduce the amount of debris in orbit. To this end all missions have to actively clean them self's up at end of life. See https://www.esa.int/Space_Safety/Clean_Space/ESA_s_Zero_Debris_approach https://www.esa.int/Space_Safety/Clean_Space/ESA_s_Zero_Debr... and https://www.esa.int/Space_Safety/Space_Debris/Mitigating_space_debris_generation https://www.esa.int/Space_Safety/Space_Debris/Mitigating_spa...
- bhouston 2y agoGreat images from the project here: https://www.esa.int/Science_Exploration/Space_Science/Gaia https://www.esa.int/Science_Exploration/Space_Science/Gaia
- jimmySixDOF 2y agoAlso available as a 3D App for desktop/VR : https://zah.uni-heidelberg.de/gaia/outreach/gaiasky https://zah.uni-heidelberg.de/gaia/outreach/gaiasky
- catlikesshrimp 2y agoWhat is the advantage of keeping the passive in orbit instead of dropping it in an ocean? If for any reason it fell from orbit, later, it could impact an important surface (city, nuclear plant), and definitely a larger area.
- ocdtrekkie 2y agoGenerally getting things out of space also requires effort/fuel. A graveyard orbit is specifically easier to get to but uninteresting from a "hitting other things" perspective.
- whartung 2y agoFolks don’t appreciate how much energy it actually takes to “fall” into the Earth or even the Sun. It’s not really intuitive when most personal experience is how hard it is to keep things from not falling.
- HappMacDonald 2y agoBoth Kerbal Space Program and Outer wilds can sometimes do a good job of driving this point home (especially in OW if you're outside of the ship). It even humbled Thor from PirateSoftware during his stream, which I found hilarious. :D
- stevage 2y agoThe only way to understand is to play Kerbal.
- tgsovlerkhgsel 2y agoMost of the attractiveness of the concept of "rods from god" relies on this misconception (if you haven't heard the term, it's a theoretical space weapon consisting of placing large tungsten rods in orbit, then dropping them on whatever needs to be destroyed in a purely kinetic strike with the energy of a massive bomb or tiny nuke). The concept isn't entirely infeasible (you could deorbit the rods actively), but the advantages over just hitting the target with an ICBM quickly dwindle once you realize you can't just "drop" them.
- sega_sai 2y agoThey also overwrote the EEPROM of the satellite computer before shutting it, because apparently they were concerned that the satellite would reawake, because it has multiple autonomous recovery modes.
- WalterBright 2y agoIt wants to live!
- Aaron2222 2y agoFrom elsewhere on ESA's site[0]: > As part of its decommissioning, the names of around 1500 team members who contributed to its mission were used to overwrite some of the back-up software stored in Gaia’s onboard memory. Personal farewell messages were also written into the spacecraft’s memory, ensuring that Gaia will forever carry a piece of its team with it as it drifts through space. [0]: https://www.esa.int/Enabling_Support/Operations/Farewell_Gaia!_Spacecraft_operations_come_to_an_end https://www.esa.int/Enabling_Support/Operations/Farewell_Gai...
- deleted 2y ago[deleted]
- pfdietz 2y ago"While the Gaia spacecraft will enjoy its well-deserved retirement" Don't anthropomorphize machines. They hate it when you do that.
- TMEHpodcast 2y agoI find it wild that we’ve been using triangular reckoning (parallax) for over a millennium, all the way back to early mariners. Measure two angles, draw a triangle, know where you are. That same method now maps galaxies. We’re still navigating the unknown with geometry.
- dreamcompiler 2y agoPretty amazing. "Gaia is measuring their positions to an accuracy of 24 microarcseconds. This is comparable to measuring the diameter of a human hair at a distance of 1000 km." https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_overview https://www.esa.int/Science_Exploration/Space_Science/Gaia/G...
- curtisszmania 2y ago[dead]
- ISL 2y agoThank you to everyone involved in the Gaia mission and to everyone whose contributions (including taxpayers) who made it possible. Gaia's data will shape our understanding of the universe for generations to come.