For one a Starlink satellite, or any LEO satellite, is moving really fast relative to a ground based telescope. It'll occult any given star for a fraction of a second.
If you're doing a narrow field long exposure with tracking, that will be problematic and you'll loose data. Most scientific observations don't do long exposures, especially measuring highly variable things like exoplanet transits.
It's more effective to stack a large number of short exposures for scientific measurements. It's much easier to eliminate noise because everything that is not noise will be transient for a single frame in the stack. You can also remove frames with things like satellites, clouds, or airplanes without losing much data.
Knowing the ephemeris of satellites also allows observations to time short exposures to avoid occultations. Astronomers have been dealing with satellites, clouds, and airplanes for a long time. Amateur astronomers might have a harder time with Starlink satellites but they will adapt just like they did with the ISS and Iridium.
>Most scientific observations don't do long exposures
Not quite the whole truth, I think you're speaking a tad beyond your expertise. While you're right that transient science generally does short exposures (TESS is 2 seconds, Kepler was 6.5, LSST will be ~20 iirc), the vast majority of astrophysical science I've been exposed to (mechanical engineer at an astrophysics research institute), 10 or 20 minute exposures are more the norm. Especially when looking at faint objects.
Doesn't take away from your main point - astronomers will adapt. I think they're perturbed by this because Starlink makes their jobs even more complex, and thus more expensive. A cost that SpaceX doesn't bear at all.
I looked up the exposure times for transient searches and went with that. It matched what astronomer friends had told me. I am not an astrophysicist.
I think astronomers have a right to be perturbed about Starlink et al. SpaceX seeming to not care about the effect Starlink satellites would have on astronomy is ridiculous. At the same time stupid mis/disinformation like this tweet is also ridiculous.
"Members of the LSST science team said last month that, assuming the full deployment of SpaceX’s Starlink satellites, nearly every exposure from the observatory within two hours of sunset or sunrise would have a satellite streak. During summer months, when twilight times longer, there could be a 40 percent impact on twilight observing time, according to the Association of Universities for Research in Astronomy, or AURA, which manages the LSST project for the National Science Foundation.
“Because of scattered light in the optics by the bright satellites, the scientific usefulness of an entire exposure can sometimes be negated,” AURA said in a statement last month. “Detection of near-Earth asteroids, normally surveyed for during twilight, would be particularly impacted. Dark energy surveys are also sensitive to the satellites because of streaks caused in the images. Avoiding saturation of streaks is vital.”"
This concern has already been addressed by SpaceX. It's worth noting that LSST is the single telescope most affected by Starlink. Since the article you posted was published, SpaceX met with the LSST people and specifically designed a sunshade to reduce the brightness of Starlink satellites on station below the threshold that will cause saturation problems. https://www.spacex.com/updates/starlink-update-04-28-2020/
They're trying to do a logical OR for all the light that comes in during a long exposure, as in an old film camera with a long shutter time.
That may have worked with analog film before we had satellites, but Starlink is just the latest and brightest addition to the sky that makes that an increasingly bad idea. Change is hard, but it's not that difficult.
Instead, AND a bunch of shorter exposures. Then, your streaks are not streaks, but a series of point sources that can be removed trivially.
And who will pay for all those necessary changes? Keep in mind that this is complex stuff, you don't just hack a perl script and be done with it. Anybody who thinks it's that simple is suffering full-blown Dunning-Kruger.
If I poo in your front yard, would you be happy with me telling you simply "well you can just remove it, what's the big deal?" Or rather, pooing regularly somewhere on a lawn in a public park that you really like and visit daily.
If you're doing a narrow field long exposure with tracking, that will be problematic and you'll loose data. Most scientific observations don't do long exposures, especially measuring highly variable things like exoplanet transits.
It's more effective to stack a large number of short exposures for scientific measurements. It's much easier to eliminate noise because everything that is not noise will be transient for a single frame in the stack. You can also remove frames with things like satellites, clouds, or airplanes without losing much data.
Knowing the ephemeris of satellites also allows observations to time short exposures to avoid occultations. Astronomers have been dealing with satellites, clouds, and airplanes for a long time. Amateur astronomers might have a harder time with Starlink satellites but they will adapt just like they did with the ISS and Iridium.