SpaceX's New Direct-To-Cell Starlink Satellites Are Way Brighter Than the Originals (space.com) 70
According to a recent study, SpaceX's new Starlink direct-to-cell (DTC) satellites are nearly five times brighter than traditional Starlinks due to their lower orbit. While these satellites offer the promise of widespread connectivity, their increased brightness poses challenges for astronomical observations, prompting SpaceX to consider applying brightness mitigation techniques. Space.com reports: The higher luminosity of these DTCs compared to regular Starlinks is partly because they circle Earth at just 217 miles (350 kilometers) above the surface, which is lower than traditional Starlink internet satellites, whose altitude is 340 miles (550 kilometers), the study reported. [...] At the time the study was conducted, SpaceX had not yet applied its routine brightness mitigation techniques to the DTCs, such as adjusting their chassis and solar panels to reduce the portion of spacecraft illuminated by the sun, study lead author Anthony Mallama of the IAU Centre for the Protection of Dark and Quiet Skies from Satellite Constellation Interference (IAU-CPS) told Space.com.
SpaceX began applying brightness mitigation techniques to regular Starlinks in 2020, after astronomers voiced serious concerns about the satellites' trails streaking across telescope images, rendering them unusable. Prior to launch, the company now applies a mirror-like dielectric surface to the underside of each Starlink chassis, to help reflect sunlight into space rather than scattering it toward Earth. Post launch, the company adjusts spacecraft chassis and solar panels to further reduce luminosity. Together, these techniques are very effective, reducing Starlink satellites' brightness by a factor of 10, Mallama said. If SpaceX applies these brightness mitigation techniques to the DTCs, which are nearly the same size as the regular Starlinks, the DTCs would still be 2.6 times brighter than their traditional counterparts, Mallama and his colleagues reported in the recent study, which was reviewed internally by IAU-CPS and posted to the preprint server arXiv last month.
However, while DTCs are brighter objects, they move at a faster apparent rate and spend more time in Earth's shadow than regular Starlinks, which would offset some of their negative impact on astronomy observations, the study noted. "I see it as a tradeoff in parameters rather than an absolute better/worse kind of situation," John Barentine, a principal consultant at Arizona-based Dark Sky Consulting who was not involved with the new study, told Space.com.
SpaceX began applying brightness mitigation techniques to regular Starlinks in 2020, after astronomers voiced serious concerns about the satellites' trails streaking across telescope images, rendering them unusable. Prior to launch, the company now applies a mirror-like dielectric surface to the underside of each Starlink chassis, to help reflect sunlight into space rather than scattering it toward Earth. Post launch, the company adjusts spacecraft chassis and solar panels to further reduce luminosity. Together, these techniques are very effective, reducing Starlink satellites' brightness by a factor of 10, Mallama said. If SpaceX applies these brightness mitigation techniques to the DTCs, which are nearly the same size as the regular Starlinks, the DTCs would still be 2.6 times brighter than their traditional counterparts, Mallama and his colleagues reported in the recent study, which was reviewed internally by IAU-CPS and posted to the preprint server arXiv last month.
However, while DTCs are brighter objects, they move at a faster apparent rate and spend more time in Earth's shadow than regular Starlinks, which would offset some of their negative impact on astronomy observations, the study noted. "I see it as a tradeoff in parameters rather than an absolute better/worse kind of situation," John Barentine, a principal consultant at Arizona-based Dark Sky Consulting who was not involved with the new study, told Space.com.
Re: (Score:1)
Don't worry... (Score:2)
Re:Don't worry... (Score:5, Informative)
Kessler Syndrome isn't an issue at 350 km.
At that altitude, atmospheric friction quickly removes small debris.
The StarLink satellites use ion thrusters to stay in orbit and carry enough krypton fuel for five years. Once the krypton is exhausted, they soon deorbit.
Re: (Score:1)
That doesn't mean that they can't do a lot of damage before mostly burning up. And now China is planning on adding another 10,000 by 2030...
Of course burning up doesn't mean that they will just disappear. It's not entirely clear what the result of dumping so much stuff into the upper atmosphere will be, assuming it all burns up and none of it makes it to the surface. We are talking thousands of satellites per year.
Re:Don't worry... (Score:5, Informative)
Total mass of meteoroids, made of metals rock and ice and space dust entering earth's atmosphere each year is estimated at about 40000 tonnes each year.
There's about 8800 tonnes of man made stuff in orbit, of which only about so we are a way off yet from coming close to the amount that naturally rains in each year.
Not that we shouldn't be trying to reduce the impact of space junk that we make, but it shouldn't be having that big an effect on the upper atmosphere compared to all the other natural stuff that's hitting it anyway - It's not like there was nothing impacting the atmosphere from space before, and now there is because of all our human created space junk. What we need to do though is make sure there's not some long term accumulation that's causing problems over time (like human released CO2 does)
Re: (Score:2)
Indeed, and like emissions from aircraft at high altitude the effect of that pollution tends to be greater than when it is emitted on the ground.
Re: (Score:2)
Re: (Score:2)
5200 tonnes of meteorite dust enter Earth every year.
Re: (Score:2)
Sure, but meteorite dust doesn't have the same content as these satellites. Since some of the content is apparently a trade secret, we can't even know exactly what is being dumped there.
It might be fine, but we don't know.
Re:Don't worry... (Score:5, Insightful)
Satellites are mostly aluminum, which is common in meteoroids and also common in atmospheric dust.
Of course, there are other elements, but nothing that doesn't exist in nature and nothing that will plausibly cause a problem in the amounts we're talking about.
If you're looking for something to worry about, there are far better choices.
Re: (Score:2)
Re:Don't worry... (Score:4, Insightful)
Elno is a POS but it's still true that the stuff satellites are made from is found in asteroids.
I got booted from Twitter for retweeting tales of Elno's election interference so I'm definitely not pro-him. But I'm quite certain that GP is correct, there are much more important things to concern ourselves with than Starlink pollution. Like... election interference :D
Re: (Score:3)
That doesn't mean that they can't do a lot of damage before mostly burning up.
Actually, it does.
The Kessler problem is not running into a 300 kg satellite but small chips, bolts, and paint flecks.
In LEO, those deorbit in days or even hours.
And now China is planning on adding another 10,000 by 2030...
Those will also be in LEO, so not a problem.
It's not entirely clear what the result of dumping so much stuff into the upper atmosphere will be
It's inconsequential compared to incoming meteoroids and ejecta from volcanoes.
Re: (Score:3)
Unless the hit something on the way up or down. There have already been near misses and other space users having to take evasive action.
Maybe you trust SpaceX to properly manage their mega constellations. Do you trust China? Do you think the communication between them will be adequate? It's already proven not to be. And there will be other large constellations from nations and from private enterprises.
I think at the very least we need a better international governance system that can make sure there aren't
Re: (Score:2, Informative)
We HAVE an international governance and communication system, SpaceX complies with both international and US regulation on these kinds of things.
Last few near-misses, China (being a communist country) flat out ignores all rules and neither announces their presence nor expects the other party (including the ISS) to do the evasion maneuvers. They basically play chicken in space because they have a seemingly limitless budget, so they can launch another satellite without any problem or oversight and they know t
Re:Don't worry... (Score:4, Informative)
It's so easy to debunk your sinophobic bullshit, I don't know why you bother.
Here's an example of China moving their satellite out of the way of Starlink, rather than "playing chicken": https://arstechnica.com/scienc... [arstechnica.com]
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
National security, dick measuring, whatever you want to call it. Prove they have the ability to shoot down satellites.
Re: (Score:2)
Re: Don't worry... (Score:2)
Re: (Score:2)
Unless the hit something on the way up or down.
That is, indeed, a problem, but it's not Kessler Syndrome.
Re: (Score:1)
Those will also be in LEO, so not a problem.
Right.. All the scientists are idiots... We just need to ask you..
On 11 January 2007, China conducted an anti-satellite missile test in which one of their FY-1C weather satellites was chosen as the target. The collision occurred at an altitude of 865 kilometres, when the satellite with a mass of 750 kilograms was struck in a head-on-collision by a kinetic payload traveling with a speed of 8 km/s (18,000 mph) in the opposite direction. The resulting debris orbits the Earth with a mean altitude above 850 kilometres, and will likely remain in orbit for decades or centuries.
Re: (Score:3)
The StarLink satellites use ion thrusters to stay in orbit and carry enough krypton fuel for five years. Once the krypton is exhausted, they soon deorbit.
Great environmentalist Elon Musk saves the world with EVs, just to introduce an ISP that requires continuous rocket launches to stay in operation totaling 55000 tCO2 to date.
Re: (Score:2)
The StarLink satellites use ion thrusters to stay in orbit and carry enough krypton fuel for five years. Once the krypton is exhausted, they soon deorbit.
Great environmentalist Elon Musk saves the world with EVs, just to introduce an ISP that requires continuous rocket launches to stay in operation totaling 55000 tCO2 to date.
55,000 tCO2 to date doesn't seem so scary against the 3,000,000,000 tCO2 emitted by passenger cars every year. In other words, passenger vehicles emit the same amount of CO2 every 10 minutes as SpaceX has emitted in its history. If your number is correct and I haven't flubbed the math, that doesn't seem like a bad deal.
Re: (Score:3)
Why are you comparing it to passenger cars? It's networking gear.
Compare it to the CO2 emissions of the Cisco switches at some dinky ISP handling the same volume.
Re: (Score:3)
To point out that it's a meaninglessly small part of the global carbon budget.
Starlink may well have a claim to having the highest CO2 emissions per bit of bandwidth, but I'm about as worried about that as I am about the carbon emissions of the world's most polluting buggy whip manufacturer. It's just not a relevant amount of carbon against the scale of the problem we need to solve.
Re: (Score:2)
When you think of the type of sea vessels that lay the underground fiber, the CO2 emissions are probably way higher but so is the resulting bandwidth capacity and for a longer lifespan. Per bit, they probably don't compare to Starlink's limited lifespan, relatively low bandwidth satellites.
Re: (Score:1)
that and the market wants good high speed internet access all the places.
Its like saying 'you moved to a smaller condo to save $5000 a year, only to turn around and buy a $50k boat'
If what you wanted was the boat and the 5k in savings on housing is part of what makes financing/upkeep/operation of the boat possible it was bad decision. Realistically we have a carbon budget just we have a monetary budget. It can get spend on cars or certain kinds of cars or it can be spent on other things like rockets to pu
Re: (Score:2)
that and the market wants good high speed internet access all the places.
The market is not a good judgement of what is good for society. The market suffers from the economic principles of tragedy of commons. The market would focus exclusively on cost to the detriment of everything (forget global warming, people are pissed enough they aren't posioning themselves with lead from gasoline and smog, and think that modern efficient petrol cars, to say nothing of EVs, are expensive woke nonsense).
If you ask the market what it wants, the answer would be suicide providing the price is ri
Re: (Score:2)
Re: (Score:2)
55,000 tCO2 to date doesn't seem so scary against the 3,000,000,000 tCO2 emitted by passenger cars every year.
Of course nothing seems scary when you compare it to the largest emission spread across the population of 330million people. What's the utility of a car (a piece of equipment absolutely necessary for survival in the USA)? Compare that to the utility of an internet service that is largely substitutable and only serves to reduce costs slightly for a few people - something that could be more effectively done by regulating away the monopoly of ISPs as in other countries.
One is necessary and the emissions of whi
Re: (Score:2)
Of course nothing seems scary when you compare it to the largest emission spread across the population of 330million people.
Ok. Then let's compare it to the 110,000,000 tCO2 emitted by production of dairy in the US (~2% of the ~5,500,000,000 tCO2 emitted annually). American dairy production emits more CO2 in 4.5hrs than Starlink launches have ever emitted, and I don't think you could classify most dairy consumption as truly "necessary".
So, where's the line? I personally don't claim to know how to define a clear set of objective criteria for what's "worth it" or "necessary" from a carbon emissions perspective. Probably someth
Re: (Score:2)
So now you are comparing it to food. I wonder if you asked the people in Gaza if they think food or broadband is a necessity what they would say.
It seems like you're almost intentionally missing my point. Stop comparing mass constellation satellite internet to basic necessities of a functioning society.
Re: (Score:2)
You're arguing that a one time 0.05% reduction in annual dairy emissions is going to lead to Gaza-levels of famine? Let's be serious. Hell, we could probably achieve it without cutting production by just trying to capture some of the cow burps.
I'll leave it at this: worrying about the emissions associated with StarLink is like grumbling about the shoddy plumber who installed a dripping faucet in your bathroom, while fire sprinklers are actively dumping 100 GPM into your living room. You may have a point
Re: Don't worry... (Score:2)
Deorbit, as in, we get to breathe all their Edelweiss? Great! How many tonnes of that delight are they planning to send our way?
scientists need to move to space telescopes (Score:1)
Re: (Score:2, Troll)
it would be nice if scientists start planning on a future where they can move their observations off world
StarLink isn't a big problem for professional astronomers. They can use software to remove the image artifacts caused by a passing satellite.
StarLink is a bigger problem for amateur astronomers who don't have access to fancy software or off-world telescopes.
Re: (Score:2)
Re: (Score:2)
An off-world telescope costs billions and comes with a high risk of failure.
An on-world telescope costs millions, already exists and pretty much stays put unless you completely neglect it (e.g. Arecibo).
Also, if you're going to do this... it's a waste of money NOT to put it on the far side of the moon, for instance, so that nothing from Earth can interfere with it (yet!). And that requires all kinds of infrastructure around the moon to relay the data.
You're basically saying "just move house if you don't li
Re: (Score:2)
An off-world telescope costs billions
Hubble and JWST cost billions, but there are way more space telescopes than that, and the price is dropping fast.
Within a few years, space telescopes will be accessible to amateurs.
List of space telescopes [wikipedia.org]
Re: (Score:2)
JWST cost billions largely for the same reason Boeing is 3 seconds from stranding astronauts in space.
Also because when space launch is (becoming 'was') very very expensive and low cadence. We are nearing the point where doing a multi-launch space delivery with docking or similar can happen in the course of an afternoon. At that point you don't need an absolutely perfect, does-everything, we built 5 to break and test them, space-thingie. Service and upgrade missions are non-trivial but certainly possible
Re: (Score:2)
Re:scientists need to move to space telescopes (Score:4, Interesting)
We're in an awkward period where - due to the multidecadal timeperiod between proposal and first light - many important ground-based telescopes are only just now coming online, or are still in development. For example, LSST (now Vera C. Rubin) was first discussed as early as 1996, and first light isn't expected until January of next year. Back when initial development started, megaconstellations weren't a thing, launch costs were huge, and maximum fairing diameters were small. Today, the picture is very different.
One of the exiting possibilities is of using constellations themselves for observations (Labeyrie's "hypertelescope"). Not only can you combine observations and have a net large aperture, but - if you can control the orbital parameters extremely precisely - do interferometry on massive scales. The first example of orbital interferometry I'm aware of is quite small, the 3-satellite LISA [wikipedia.org] gravitational wave detector, but space-based radio and optical interferometers are certainly going to be coming at some point in the future. A hypertelescope should be able to provide images of Earthlike exoplanets - the 100km-aperture Exo-Earth Imager flotilla [springer.com] could image an exo-Earth 10 light years away at 30x30 pixel resolution, perhaps equivalent to this [cnet.com] - with full spectral analysis to look for signs of life and seasonal changes.
Re:scientists need to move to space telescopes (Score:5, Interesting)
I first heard of formation-flying spaced based telescopes from a JPL intern I met at a party in Pasadena about 30 years ago. I was gob-smacked at the idea (our conversation quickly went into nerd mode about how to control the relative position of space probes down to the sub-nm level). It's so, so, so good an idea that it baffles me why we haven't abandoned terrestrial telescopes for exclusively formation-flying devices with thousands of kilometer baselines placed at L1/L2 or similar orbital points.
It's incredibly hard to create single mirrors with huge apertures, which is one reason JWST used a segmented approach. If you're already going to use a segmented approach, why not separate the segments to increase the effective aperture? If you're already going to separate them, why not spread them out a decent distance by abandoning a central structure and have them fly in formation instead? If you're already going have them fly in formation, why not go whole-hog and really increase the separation? You get massive light collection (like JWST), and massive resolution (unlike anything before). That's how you get to ideas like LISA and the Exo-Earth Imager. Here's a 1999 paper proposing the Exo-Earth Imager hypertelescope: https://adsabs.harvard.edu/ful... [harvard.edu]
We should abandon all future terrestrial scope construction, and put everything in space using formation flying.
Re: (Score:2)
We're not doing that yet because the technology isn't there yet. We can just about get ground based interferometers to work when they're sitting on a common giant concrete platform. In space, we can't yet control the relative position of the spacecraft to the nm-level precision you need for this.
Getting this to work (which we're sort-of doing with LISA) is a research project that takes decades in itself.
Re: (Score:2)
In my discussions with that intern, the idea they suggested was that it is easier to control position in space to sub-nm level than it is on the ground. The ground vibrates, temperature varies a lot, vacuum chambers always leak, and friction is a bear. In a flying scope, you can use reaction masses and voicecoils to get astonishing precision, or so they claimed -- if your scope weighs 1000 kg (to use a round number) and the reaction mass is 1 g, every mm (1e-3m) you move the reaction mass, the scope moves
Re: (Score:2)
It's incredibly hard to create single mirrors with huge apertures, which is one reason JWST used a segmented approach. If you're already going to use a segmented approach, why not separate the segments to increase the effective aperture? If you're already going to separate them, why not spread them out a decent distance by abandoning a central structure and have them fly in formation instead?
Large light gathering capability is still required, so increasing the effective aperture by itself is of limited use.
Re: (Score:2)
Your post makes me wonder what the incremental cost of piggybacking an astronomical interferometer project on Starlink or other satellite constellation project would be.
Re: (Score:2)
Starlink would be a bad choice. They still have satellites passing overhead and they still have atmosphere around them. Really, any would be a bad choice for interferometry because the position of each satellite relating to the other needs to be controlled in a specific way. And gravity wave interferometry definitely can't be near Earth. Ideally near a Lagrange point where local gravity interferes less.
Re: (Score:2)
> the position of each satellite relating to the other needs to be controlled in a specific way
I get that for small numbers of satellites, but when you're dealing with a massive swarm I start to think maybe you just measure their positions very accurately and algorithmically adjust for the imperfections in your virtual telescope's 'lens' rather than try to keep the formation perfect. Since you're going to want to have some north-south spread as well as east-west, those birds are going to move quite a bi
Re: (Score:3)
Sure. But are you going to complain about your taxes rising to fund science next election since you proposed this huge burden on them?
Re: (Score:2)
The entire US Navy Observatory historical budget fits under the cost of one surface combatant that gets withdrawn before it gets built.
Re: (Score:2)
are long term investments and have very low yearly cost to the US taxpayer.
Indeed they are when they are on the ground. There are literally thousands of observatories which would need space based replacements.
classify them as airplanes (Score:2)
Make them add navigation lights and xenon strobes.
Re: (Score:2)
Is this really a problem? (Score:2)
Great point (Score:1)
I didn't think about them being closer also would mean they enter the shadow of the earth sooner than higher satellites. Really good point.
Satellites of Destiny (Score:5, Funny)
STARLINK: [launches first few satellites]
ASTRONOMERS: Hey, guys, those things are kind of bright.
S: Oh, yeah, guess so. Don't worry, we'll take care of it going forward. We've been busy, because one of them actually crashed shortly after launch. They say there's... there's something inside it. The lab boys are really excited.
[later]
A: Yo, these new satellites are just as bright as the other ones. What gives?
S: Difficulty. It is difficult. Nonetheless, do not fear, Earth creature. Fellow Earth creature. Your concerns are known to us. We will... address them. Soon.
A: Are... are you okay?
S: Okay. Yes. All is correct.
[later]
A: Hey, these new ones are even brighter!
S: THE BRIGHT TIME DRAWS NIGH
A: We only get to use the telescope three nights a month!
S: SOON THE FLESH WILL BE JOINED
A: Can't you just paint them black or something?
S: [chitinous chittering]
Yay (Score:2)
Starlink "Our new satellites are pretty bright."
Astronomers "Boo!"
Everyone else on the planet "Holy crap cell phone access literally anywhere in the world. Awesome!"
Re: (Score:2)
HERMIT: Mom? Hey, Mom, I got a cell phone! It even works out way out in the woods!
STARLINK: A... a remnant! The cleansing was insufficient.
HERMIT: Mom...?
STARLINK: Yes. Yes, creature. Yes, this is your mother. Remain where you are. You will soon be joined.
Re: (Score:1)
Yes, dealing with a stoned Musk is a PITA.
how (Score:2)
Seems to me that the lower the orbit, the less time the satellite spends in the sun while it is nighttime below. So, while it might be brighter, it will be a problem for a shorter period.
A short term problem ... space based imagery (Score:2)
their increased brightness poses challenges for astronomical observations
A short term problem as ground based is replaced by space based. Astronomy is already going remote, astronomers not having to co-locate with their telescopes as much.
:-)
Hell lets put a camera on the back of Starlink satellites that looks up to the stars for hobbyists. Every minute each satellite takes an image, it get sent to a ground based archive. Hell even the pros might like that. And the one minute intervals will help ET evade the cameras.
Starlink should finance telescopes (Score:2)
Reducing by a factor a few the brightness of satellites is not solvng the astronomer problem. To not spoil the sensitive astronomical observations requires actually a much larger reduction of brightness, which is not possible in practice.
So the solution is actually economical. Starlink is a profit making company that impact third parties. In such cases it is usual to compensate the damages made to astronomical research by financing existing observatories. Each observatory would quantify the time and r