Astronomy group calls for urgent action on SpaceX Starlink satellites
newscientist.com
newscientist.com
The article is substantially more sensational than the IAU letter is is based on:
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 radio emissions are well-regulated already, and appropriate measures are in place well before the launch is even approved.
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.
(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.
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.
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.
Currently no country has a well-working solution for that, nor does any company (not even SpaceX themselves)
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.
IOW, is a speculative, unproven idea.
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.
So either space astronomy becomes much easier/cheaper and we get megaconstellations, or megaconstellations won't happen.
Synthetic apertures using interferometry may solve that eventually but we're not there yet it looks like for really high resolution images.
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.
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.
...especially when combined with proper orientation of the satellites.
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.
Their destination orbit is 550km, and were launched around 400km IIRC.
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.
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.
Anyone know what the apparent magnitude of ISS, Dragon, and Star Link would be?
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.
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.
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.
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.
(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.)
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.
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.
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