Astronomy group calls for urgent action on SpaceX Starlink satellites(newscientist.com)
newscientist.com
Astronomy group calls for urgent action on SpaceX Starlink satellites
https://www.newscientist.com/article/2205172-astronomy-group-calls-for-urgent-action-on-spacex-starlink-satellites/
73 comments
So, realistically, it's going to mean that ground-based telescopes become less productive. Some won't be affected much at all (narrow FoV), while others may have to fundamentally shift how they operate (wide FoV). More exposures will need to be made to overwrite any satellites that pass through the field. This is already done due to existing satellites, so it's simply a question of rates.
The radio astronomy issue is potentially more significant, but then I don't understand why these issues weren't raised when the spectrum was being allocated.
The radio astronomy issue is potentially more significant, but then I don't understand why these issues weren't raised when the spectrum was being allocated.
> why these issues weren't raised when the spectrum was being allocated
Because they are bogus. This is riding on a wave of populism, at a time when journalists woke up to an "Elon's train" and twitter was buzzing with many people who saw a satellite with their naked eye for their first time.
Actual professional astronomers would either realize this is not such a big problem, or would raise the issues during the spectrum allocation, or would raise issues during the whole time SpaceX was showing animations of the finished constellation to all their fans etc etc... there was a lot of time, no way somebody whose project depended on free skies wouldn't be prepared.
Because they are bogus. This is riding on a wave of populism, at a time when journalists woke up to an "Elon's train" and twitter was buzzing with many people who saw a satellite with their naked eye for their first time.
Actual professional astronomers would either realize this is not such a big problem, or would raise the issues during the spectrum allocation, or would raise issues during the whole time SpaceX was showing animations of the finished constellation to all their fans etc etc... there was a lot of time, no way somebody whose project depended on free skies wouldn't be prepared.
This only doubles the number of satellites iirc, I doubt it will mean many have to fundamentally shift how they operate.
NIMBYism has reached the orbit.
It is my guess that the majority of those who raise concerns already have communication access, specifically high speed internet access, provided by other means. I would further guess that they are considering the cost to themselves and not the gains to others. Would they be willing to pay the price to provide internet access by other means to those who would be served by these satellites, or are they hoping that those who don't have it will continue to be able to do without?
Let me pose this unfair question back at you. Are you willing to pay the price for providing an alternate means of sky observation at a scale suitable for astronomy, and for cleaning up the debris that might result from expiration of, or collisions between, tens of thousands of commercial satellites?
You are implying that launching many commercial (American) satellites is the best, or even a good, solution to the problem of many people not having what you consider adequate internet. Moreover, apparently this problem is so urgent and the solution so perfect that you feel the need to chastise these scientists for even expressing concern. I don't think you are approaching this discussion in a fair manner.
You are implying that launching many commercial (American) satellites is the best, or even a good, solution to the problem of many people not having what you consider adequate internet. Moreover, apparently this problem is so urgent and the solution so perfect that you feel the need to chastise these scientists for even expressing concern. I don't think you are approaching this discussion in a fair manner.
>Are you willing to pay the price for providing an alternate means of sky observation at a scale suitable for astronomy, and for cleaning up the debris that might result from expiration of, or collisions between, tens of thousands of commercial satellites?
I feel there is an implication that being able to observe the sky, and specifically the extent this is degraded, is comparable to the extent one is excluded from modern society without a fast internet connection.
>not having what you consider adequate internet.
I would think all the students who are unable to complete school assignments due to lack of internet access, sometimes with web pages outright failing to load over dial-up, would be the one's whose considerations of adequate internet we need to rest our judgments upon. One might say that a school shouldn't engage in having such an unfair requirement, but then that would mean limiting tools accessible to other students and to teachers.
>for even expressing concern
From the article:
>and calling for regulation
>I don't think you are approaching this discussion in a fair manner.
I feel a standard of fairness is being applied in a manner most unbefitting itself.
I feel there is an implication that being able to observe the sky, and specifically the extent this is degraded, is comparable to the extent one is excluded from modern society without a fast internet connection.
>not having what you consider adequate internet.
I would think all the students who are unable to complete school assignments due to lack of internet access, sometimes with web pages outright failing to load over dial-up, would be the one's whose considerations of adequate internet we need to rest our judgments upon. One might say that a school shouldn't engage in having such an unfair requirement, but then that would mean limiting tools accessible to other students and to teachers.
>for even expressing concern
From the article:
>and calling for regulation
>I don't think you are approaching this discussion in a fair manner.
I feel a standard of fairness is being applied in a manner most unbefitting itself.
> and for cleaning up the debris that might result from expiration of, or collisions between, tens of thousands of commercial satellites
FWIW, at the altitudes Starlink operates at, that completely hypothetical scenario would only take a few years to remedy, and would cost $0 as the debris naturally de-orbits due to atmospheric drag.
FWIW, at the altitudes Starlink operates at, that completely hypothetical scenario would only take a few years to remedy, and would cost $0 as the debris naturally de-orbits due to atmospheric drag.
> Are you willing to pay the price for providing an alternate means of sky observation at a scale suitable for astronomy, and for cleaning up the debris that might result from expiration of, or collisions between, tens of thousands of commercial satellites?
SpaceX is literally spearheading both technologies and business models required to do exactly that, and Starlink is critical to this as a source of funding.
SpaceX is literally spearheading both technologies and business models required to do exactly that, and Starlink is critical to this as a source of funding.
The almost-poetic irony of blinding ourselves to the outer world to better navel-gaze our digital nirvana.
(To the astronomy-haters on the thread: Y'all realize we can have connectivity and clear skies, right? There's no intrinsic trade-off here.)
(To the astronomy-haters on the thread: Y'all realize we can have connectivity and clear skies, right? There's no intrinsic trade-off here.)
Why not paint the satellites black on the bottom?
Generalizing, you're asking the "obvious" question: "these are first-run prototypes, and short-lived, so why not mitigate the brightness in future?"
And yes, SpX has said they plan to get telescope images to determine the bright bits, and to do the right thing.
On the meta question, of why societal discussion is so far from sane... Well, there are perverse incentives... And it's not like our profession has spent the last few decades working diligently to improve discussion tooling... we've done almost nothing on it at all.
And yes, SpX has said they plan to get telescope images to determine the bright bits, and to do the right thing.
On the meta question, of why societal discussion is so far from sane... Well, there are perverse incentives... And it's not like our profession has spent the last few decades working diligently to improve discussion tooling... we've done almost nothing on it at all.
On a more upbeat note, Wikum[1] is an example of summarizing threaded discussion (like HN), and Tilda[2] of tagging chat (like Slack).
In addition to absorption (painting it "black"), one can also scatter (spread it out), and deflect (shine somewhere you don't care about), shadow, and mask, and otherwise change geometry to change light paths. Optical stealthing of satellites is a thing, with somewhat limited accessible literature. Though there is some[3], seemingly mostly Chinese.
[1] http://wikum.csail.mit.edu/ has examples like http://wikum.csail.mit.edu/visualization_flags?id=23&owner=N... and http://wikum.csail.mit.edu/visualization_flags?id=20&owner=N... [2] https://people.csail.mit.edu/axz/tilda.html [3] https://www.mdpi.com/2079-6412/9/3/193/htm
In addition to absorption (painting it "black"), one can also scatter (spread it out), and deflect (shine somewhere you don't care about), shadow, and mask, and otherwise change geometry to change light paths. Optical stealthing of satellites is a thing, with somewhat limited accessible literature. Though there is some[3], seemingly mostly Chinese.
[1] http://wikum.csail.mit.edu/ has examples like http://wikum.csail.mit.edu/visualization_flags?id=23&owner=N... and http://wikum.csail.mit.edu/visualization_flags?id=20&owner=N... [2] https://people.csail.mit.edu/axz/tilda.html [3] https://www.mdpi.com/2079-6412/9/3/193/htm
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Heat? They are shining because they are reflecting sunlight. Now paint them black and have them warm up. They then have to dissipate the excess heat in a vacuum...
You're overly simplifying, but this musk tweet [0] can indeed be read as going somewhat in that direction.
[0] https://twitter.com/elonmusk/status/1132908689860415488
[0] https://twitter.com/elonmusk/status/1132908689860415488
I'm not sure which is worse, a shiny satellite that screams where it is (so you can avoid it) or a dark satellite that silently blocks a patch of the sky.
By far the shiny satellite is worse. Besides, the satellites are tracked carefully by multiple parties, so any serious astronomical observation that could even theoretically be sensitive to a sub-millisecond obscuration of a ~microradian portion of the sky (such as certain exoplanet searches) would be well aware of this ahead of time (and atmospheric aberration would be a far greater effect). A dark satellite is effectively irrelevant to optical ground astronomy.
the shiny one. because telescopes aren't in the habit of avoiding shiny things; they use the databases of where all of this stuff is and do the math to figure out where it will be.
the dark objects at least won't introduce extra photons into the optics to refract around, when they're in your field of view but not obstructing the thing you were actually trying to look at.
the dark objects at least won't introduce extra photons into the optics to refract around, when they're in your field of view but not obstructing the thing you were actually trying to look at.
What is more useful, satellites or astronomers being able to view the stars clearly from the planets surface. Genuine question, but it seems to me that in the long run satellites would win out.
Well, in the really long run, a clear view of potential celestial destinations may be paramount :)
Yeah, but if you're thinking on those timescales you'd probably be better off using orbital telescopes, or telescopes located on other planets or moons with little to no atmosphere.
Satellites and the commercialization of space will be important to enabling that level of space-borne infrastructure, so even in the really long run the utility of satellites probably still wins out.
Satellites and the commercialization of space will be important to enabling that level of space-borne infrastructure, so even in the really long run the utility of satellites probably still wins out.
Orbital telescopes are much better suited for this.
They're also much much more expensive and less flexible. With earth based satellites new experiments with new instrumentation is easy, in space currently we have no way to fix any issues.
...with the kind of capabilities that enable megaconstellations (low cost launch, inexpensive space hardware replaced regularly every few years), neither of those things will be true.
So either space astronomy becomes much easier/cheaper and we get megaconstellations, or megaconstellations won't happen.
So either space astronomy becomes much easier/cheaper and we get megaconstellations, or megaconstellations won't happen.
Optics put a lot of design constrains on telescopes that mean they'll always be large items, when you're trying to look really far away at really dim objects you just need a lot of surface area to collect as much light as possible and the size of the object you can resolve is directly linked to the size of the aperture of the telescope you're using.
Synthetic apertures using interferometry may solve that eventually but we're not there yet it looks like for really high resolution images.
Synthetic apertures using interferometry may solve that eventually but we're not there yet it looks like for really high resolution images.
Right, I meant cost in terms of cost per unit dry mass, not just miniaturizing existing satellites. Starlink satellites are really cheap per unit dry mass, not just per satellite. Starship will be super cheap per unit dry mass, enabling ever-larger space telescopes. NASA even tweeted out one concept out for an aperture much larger than JWST using SpaceX's Starship: https://twitter.com/nasagoddard/status/1116310431969239040?l...
They might get cheap to launch but they'll be quite expensive to build for the foreseeable future.
I don't see why they need to be. SpaceX has been able to reduce the cost of building space hardware with Starlink by an order of magnitude. When things are cheaper to launch, you can find ways to reduce the cost to build those things.
They're large and complex and the optics for each are generally pretty custom to the application they're being built for. Starlink benefits from decades of work in cubesats and radio transmitters to make most of it's components COTS or nearly COTS. There's not really a lot of earth based applications for gold coated beryllium hexagons to make making a JWST style mirror cheap and easy.
That's inconsistent with the fact that ground-based astronomy is able to build large and complex optics pretty cheaply, which is the basis for this complaint to begin with. By leveraging these things, you could build an inexpensive space telescope. No one has done so because it has only recently become fairly cheap to launch stuff.
JWST is such a terrible example of a space telescope done with good cost constraints, BTW. And that kind of infrared astronomy which needs gold-coated mirrors and 20 Kelvin operating temperatures can't be done on the ground at all. We were discussing near-visible optical instruments and comparing to ground astronomy.
JWST is such a terrible example of a space telescope done with good cost constraints, BTW. And that kind of infrared astronomy which needs gold-coated mirrors and 20 Kelvin operating temperatures can't be done on the ground at all. We were discussing near-visible optical instruments and comparing to ground astronomy.
We can and have fixed space telescopes before, probably the most famous example is Hubble and its poor sight. https://en.wikipedia.org/wiki/Hubble_Space_Telescope#Flawed_...
To be fair, that was the killer app of the space shuttle (ie. satellite interception and capture). We've lost that capability, and nothing on the medium term drawing board regains that.
You're right we don't currently, that just means its time to boot up space race 2, I hope China's space program kicks NASA back into high gear, shift a couple of the DOD's billions around and get space race 2 electric boogaloo going.
Not true. SpaceX envisions using Starship (the same vehicle SpaceX would need to be able to launch 12,000 satellites) for satellite interception and capture. No Starship, no 12,000 satellites.
You don't need Starship for limited constellations to cause issues with Earth based observations though. Also SpaceX isn't the only one that's going to be wanting to make a constellation.
Well in that case, we've had limited constellations that cause issues for Earth based observations for decades. (Note: this is one hint that the risk here is exaggerated... dealing with satellites has been a thing for a very, very long time. Filtering out satellite tracks is easy and common, and modern digital imaging and data storage techniques have made satellite track removal ever easier. And many satellites--particularly space stations--are orders of magnitude brighter than Starlink satellites will be.)
So which space shuttle should we use to fix James Webb if anything would go wrong after the launch?
Currently no country has a well-working solution for that, nor does any company (not even SpaceX themselves)
Currently no country has a well-working solution for that, nor does any company (not even SpaceX themselves)
JWST is for researching high-redshift object - the most distant things we can see in the universe. It's not a planet-hunter. And it will be much further away than other satellites, so they would be more easily serviced. (Not that it's easy, I just think you picked a bad example.)
> JWST is for researching high-redshift object - the most distant things we can see in the universe. It's not a planet-hunter.
JWST is a general purpose observatory. It will make significant advances for high-redshift objects. It will not survey large numbers of star for new planets, but it will be able to observe and characterize planets that have been identified by other missions/observatories.
JWST is a general purpose observatory. It will make significant advances for high-redshift objects. It will not survey large numbers of star for new planets, but it will be able to observe and characterize planets that have been identified by other missions/observatories.
SpaceX is working on Starship, which should be capable of Shuttle-like service missions. (JWST is much more fragile than Hubble, however, so you'd need to build a custom servicing solution... but JWST is not representative of space telescopes generally.) In fact, SpaceX is counting on Starship to deploy their full constellation. No Starship, no 12,000 satellites.
I think JWST is going to look a lot like the future of space telescopes. There's hard requirements that make larger satellites better for observation, principally because larger aperture == better resolution and also because the larger mirror gathers more light so we can look at dimmer objects.
It's not the size of JWST, it's the fact that it's deeply cryogenic and uses enormous, fragile multilayer insulation to remain so.
Indeed, larger apertures will be used increasingly. And this megaconstellation actually enables that indirectly. SpaceX is counting on their Starship launch vehicle to deploy the vast majority of their 12,000 satellite constellation, and indeed large launch vehicles (particularly reusable ones) require a lot of payloads to justify their development cost. But large launch vehicles also enable ever-larger telescopes, whose cost is only affordable if those launch vehicles are reusable.
NASA is already buying into it. Here's NASA Goddard tweeting out the larger-than-JWST concept called LUVOIR inside SpaceX's Starship (which again relies on the megaconstellation for demand): https://twitter.com/nasagoddard/status/1116310431969239040?l... ...and yet larger apertures will require in-space assembly over several launches, again only really affordable if there's enough commercial launch demand (i.e. from megaconstellations in particular) to justify these large reusable launch vehicles.
My point of view is that if we're going to be a really spacefaring civilization, it's reasonable that you'll be able to see human artifacts in the sky. Starlink is actually fairly easily stealthed, but other things (space based solar power stations, large space stations, in-space manufacturing depots, etc) may not be so easily hidden. Is the fact that human artifacts may be detectable in the night sky reason enough to disallow spacefaring?
EDIT: Note that the IAU letter is way more reasonable than almost all the media takes on this issue.
Indeed, larger apertures will be used increasingly. And this megaconstellation actually enables that indirectly. SpaceX is counting on their Starship launch vehicle to deploy the vast majority of their 12,000 satellite constellation, and indeed large launch vehicles (particularly reusable ones) require a lot of payloads to justify their development cost. But large launch vehicles also enable ever-larger telescopes, whose cost is only affordable if those launch vehicles are reusable.
NASA is already buying into it. Here's NASA Goddard tweeting out the larger-than-JWST concept called LUVOIR inside SpaceX's Starship (which again relies on the megaconstellation for demand): https://twitter.com/nasagoddard/status/1116310431969239040?l... ...and yet larger apertures will require in-space assembly over several launches, again only really affordable if there's enough commercial launch demand (i.e. from megaconstellations in particular) to justify these large reusable launch vehicles.
My point of view is that if we're going to be a really spacefaring civilization, it's reasonable that you'll be able to see human artifacts in the sky. Starlink is actually fairly easily stealthed, but other things (space based solar power stations, large space stations, in-space manufacturing depots, etc) may not be so easily hidden. Is the fact that human artifacts may be detectable in the night sky reason enough to disallow spacefaring?
EDIT: Note that the IAU letter is way more reasonable than almost all the media takes on this issue.
Your comment assumes we still need fleshy meatbags wearing clunky suits in orbit to fix things. This was true 15 years ago, but I'm not convinced it's still true today. A couple of repair drones housed at the ISS combined with repair parts brought up along with normal resupply missions could probably be made to work if it was deemed cost effective.
The ISS isn't in a particularly good orbit because it's highly inclined (so Russia could easily launch to it) which is an expensive issue to fix dV wise unless all the target satellites are in a similarly inclined orbit. In terms of making them easy to swap out that's certainly possible but it will add weight compared to a monolithic satellite and so far we have very very little experience building and repairing things in space without using people.
This is a misconception. The ISS is not in an orbit that’s suitable for repairing satellites in other orbits.
> could probably be made to work
IOW, is a speculative, unproven idea.
IOW, is a speculative, unproven idea.
We did but not any more 1) there's no longer anything like the shuttle available the only thing that could get close would take two launches to stage the parts and another for the crew capsule (not to mention most US capsules would have to evacuate the entire capsule to go outside iirc) and 2) most of the current space based telescopes like James Webb will be much much further out than Hubble was and most that get announced are also planned to orbit much further from Earth.
Both
Tragic, and yet the future of astronomy is clearly with extraterrestrial observation platforms.
We only really need to send telescopes to space for observing the wavelengths that are otherwise absorbed by the atmosphere. Adaptive optics are almost unbelievably effective at cutting out the interference that the Hubble telescope is practically obsolete (and indeed obsolete, since it will be de-orbited soon).
> the Hubble telescope is practically obsolete (and indeed obsolete, since it will be de-orbited soon).
This isn't quite accurate. Hubble has ultraviolet capabilities that are impossible to achieve from the ground (due to the atmospheric absorption). JWST won't replace this functionality. Also, while AO can achieve similar or better angular resolution, it can be difficult to characterize the point spread function (PSF) of the AO system. By contrast the PSF of HST is incredibly stable. Knowing the PSF and having it be stable is key for some types of science.
This isn't quite accurate. Hubble has ultraviolet capabilities that are impossible to achieve from the ground (due to the atmospheric absorption). JWST won't replace this functionality. Also, while AO can achieve similar or better angular resolution, it can be difficult to characterize the point spread function (PSF) of the AO system. By contrast the PSF of HST is incredibly stable. Knowing the PSF and having it be stable is key for some types of science.
Last night (1900GMT), I’m sure we saw a Dragon capsule a few degrees ahead of the ISS as it went overhead. That’s with the naked eye.
Anyone know what the apparent magnitude of ISS, Dragon, and Star Link would be?
Anyone know what the apparent magnitude of ISS, Dragon, and Star Link would be?
ISS is approximately the same magnitude as the entire SpaceX megaconstellation combined. At its peak, ISS is brighter than Venus and brighter than 20,000 Starlink-sized satellites.
Would it be a difficult challenge to develop a imaging process that ignores such fast movements of a object?
Musk said they would try to avoid impact, making such an software product and releasing it for free would be a great step in that direction. I imagine, also, that good night shots are long exposures or multiple long exposures.
Musk said they would try to avoid impact, making such an software product and releasing it for free would be a great step in that direction. I imagine, also, that good night shots are long exposures or multiple long exposures.
Satellite tracks are already super common and are already algorithmically removed from long exposures (not hard when you're compositing from a stack of images).
The satellites are hard to spot already, the satellites still haven't been fully risen to their orbits, the solar arrays presumably aren't yet tracking the sun because they need to be oriented to point the engine in the right direction. Any complaints about this constellation seem either late (completely hypothetical and should been raised years ago when approval was sought from the FCC) or early (based on real world data that doesn't yet exist).
The article is substantially more sensational than the IAU letter is is based on:
https://www.iau.org/news/announcements/detail/ann19035/
The article is substantially more sensational than the IAU letter is is based on:
https://www.iau.org/news/announcements/detail/ann19035/
> The satellites are hard to spot already,
To the naked eye, perhaps. But large telescopes and their instruments are incredibly sensitive. So even if the satellite constellations are minimally visible to the naked eye they can still have a substantial impact on science.
Additionally, these satellites are likely to be very bright in the radio portion of the spectrum (due to their uplink/downlink), which could negatively affect radio telescopes.
To the naked eye, perhaps. But large telescopes and their instruments are incredibly sensitive. So even if the satellite constellations are minimally visible to the naked eye they can still have a substantial impact on science.
Additionally, these satellites are likely to be very bright in the radio portion of the spectrum (due to their uplink/downlink), which could negatively affect radio telescopes.
Satellite track removal is already a well-understood capability that serious telescope projects already do.
Satellite radio emissions are well-regulated already, and appropriate measures are in place well before the launch is even approved.
Satellite radio emissions are well-regulated already, and appropriate measures are in place well before the launch is even approved.
> The article is substantially more sensational than the IAU letter is is based on
The article uses simpler language, but doesn't seem more sensationalist.
> The satellites are hard to spot already
I'm not exactly an amateur astronomer, but I do get my telescope out every couple of weeks. If I'm out not too long after sunset, I'll typically spot two or three satellites without trying, so I can imagine "real" astronomers are concerned.
Tangentially, some times it's fun to track satellites on purpose. Some people use fast tracking mounts to photograph them.
The article uses simpler language, but doesn't seem more sensationalist.
> The satellites are hard to spot already
I'm not exactly an amateur astronomer, but I do get my telescope out every couple of weeks. If I'm out not too long after sunset, I'll typically spot two or three satellites without trying, so I can imagine "real" astronomers are concerned.
Tangentially, some times it's fun to track satellites on purpose. Some people use fast tracking mounts to photograph them.
While I share the community's concern for preserving the dark skies wherever possible, is it not premature considering _none_ of the 60 satellites launched have yet to reach their destination altitude?
Why would this be significant? The separation altitude in the launch was around 450km, according to the numbers in the livestream. The orbital shell being targeted is 550km. This doesn't constitute a large difference in visibility.
Due to the inverse square law, it constitutes half an (astronomical) order of magnitude in visibility. For satellites that are already dim, that's a significant difference.
...especially when combined with proper orientation of the satellites.
...especially when combined with proper orientation of the satellites.
Since it likely also affects satellite orientation and possibly configuration. Also since brightness obeys a square law so they should ignoring effects other than distance be 1.5 times their final level still.
A factor of 1.5 doesn't strike me as being enough to suggest the problem will go away (the satellites become too small a part of images to matter). Additionally, the satellites are not two-dimensional, so there is no orientation in which they would not occlude the view.
It appears that the objections are not to the size of the satellites (they are relatively small compared to other satellites in LEO), but that they are to be highly numerous. The planned size of the constellation is 11927 satellites.
The frequency with which these satellites photobomb astronomical images is the concern, rather than how much area they affect. In fact, their being smaller makes them more of a menace, as they will be more challenging to spot, or easier to confuse with an astronomical entity.
This said, I don't think this is a strong argument against putting such satellites in orbit, and progress will and should continue. Astronomers will have to be careful to avoid contamination.
It appears that the objections are not to the size of the satellites (they are relatively small compared to other satellites in LEO), but that they are to be highly numerous. The planned size of the constellation is 11927 satellites.
The frequency with which these satellites photobomb astronomical images is the concern, rather than how much area they affect. In fact, their being smaller makes them more of a menace, as they will be more challenging to spot, or easier to confuse with an astronomical entity.
This said, I don't think this is a strong argument against putting such satellites in orbit, and progress will and should continue. Astronomers will have to be careful to avoid contamination.
For my part, I wouldn't put it past the minds that land orbital class, first stage rockets on the regular to come up with something that surprises us. Not suggesting that's a meaningful strategy for ensuring dark skies, just pointing out they've surprised us more than once!
Interesting, what is your source on that? Do they have substantial onboard fuel to boost into higher orbits at a later date? Even if they do, they are already in LEO so I'd think must be quite close to their destination orbits.
They use Krypton-fueled Ion thrusters; they're much like Xenon thrusters, but Krypton is cheaper. Being a LEO constellation, they require propulsion to maintain their orbit.
Their destination orbit is 550km, and were launched around 400km IIRC.
Their destination orbit is 550km, and were launched around 400km IIRC.
Why didn't the IAU petition the FCC during the comment period for SpaceX's application? Seems sorta weird to wait for the first launch to express concerns when the application was submitted to the FCC many months ago (and I think I recall an earlier version years ago).
(Or if they did, could someone provide the link? I'm not able to find it.)
(Or if they did, could someone provide the link? I'm not able to find it.)
I'm calling for urgent action on astronomy groups.