Capella's Earth-Imaging Satellites Are Deorbiting Faster Than Expected

Capella Space's synthetic aperture radar satellites are falling back to Earth much sooner than than the three years they were anticipated to operate, according to publicly available satellite data. TechCrunch reports: The startup has launched a total of ten small satellites to low Earth orbit since 2018, including eight in its family of "Whitney"-class spacecraft. Five of these satellites have reentered the atmosphere since the end of January of this year, including three of the Whitneys. Those Whitney sats were in orbit for less than two-and-a-half years; one, Capella-5, was in orbit for less than two years. That leaves five of the constellation in orbit, including the Capella-9 and Capella-10 launched on March 16, which are operating at an altitude of around 584 km and 588 km, respectively.

According to filings with the Federal Communication Commission, the propulsion system of Capella-9 was built by Phase Four. At least one of the satellites that has reentered prematurely, Capella-5, also used Phase Four propulsion. In that same filing from March 2022, Capella said its Capella-9 satellite would operate at an orbital altitude of 525 km, and maintain an altitude between 475-575 km for three years. It seems this is the typical mission profile of Capella satellites. But Capella-7 and Capella-8, launched in January 2022, appear to be now operating below 400 kilometers, and will likely deorbit in a matter of weeks to a few months. The unexpected decay could be due to a problem with the propulsion system, or a systematic miscalculation of its requirements.

"Probably they [Capella-7 and Capella-8] will reenter in Sep-Oct or so," astronomer and analyst Jonathan McDowell said when reviewing the data at TechCrunch's request. "I suspect propulsion failures but certainly it isn't clear." In a statement to TechCrunch, Capella CEO Payam Banazadeh confirmed that some of the satellites have been deorbiting faster than expected "due to the combination of increased drag due to much higher solar activity than predicted by NOAA and less than expected performance from our 3rd party propulsion system." "We have upgraded our propulsion system on all future satellites to account for these facts, including the launch of our next generation satellite Acadia-1, currently scheduled for launch on August 5th 2023. We plan to launch eight of our next generation Acadia satellites over the next 12 months," he added.

Increased sun activity?

[Z00L00K]

To me it could be due to increased sun activity. After all the sun spot activity is above the predicted [noaa.gov].

Or is it global warming making the atmosphere swell?

Re:Increased sun activity?

[dgatwood]

That seems extreme. If solar events had that much effect, how do we still have satellites?

Other low-earth-orbit satellites carry more fuel (and may have more efficient propulsion), and thus can deal with the extra fuel usage required to stay in orbit.

Also, luck can have something to do with it, too. If a satellite is behind the planet Earth at the time, it wouldn't be affected by solar winds much (if at all). If it is moving away from the sun, it would be pushed into a higher orbit (almost like getting a free fuel-up from the sun). If it is between the planet and the sun or is heading towards the sun, it is affected negatively.

And the surface area relative to mass matters, too. A large satellite with low mass would be impacted more by solar radiation than a small satellite with high mass, in much the same way that a sail is affected by wind more than a bullet. For that matter, IIRC, even the color of the surface can affect how much solar radiation causes a course deviation.

So the difference could theoretically involve any number of factors.

Re:

[Fuck_this_place]

Yeah. you're still making it sound like they were hit by something they already knew about. If it was that bad, seems like it would be common knowledge in that field. The sun's activities are not exactly secret. If that was the problem it would be in the story I think.

I mean, I've been watching satellites wiz by overheard for half a decade.... I've never heard of solar activity de-orbiting one of them yet.

Re:

[Fuck_this_place]

*Century... oops.

Re:Increased sun activity?

[dgatwood]

Yeah. you're still making it sound like they were hit by something they already knew about. If it was that bad, seems like it would be common knowledge in that field. The sun's activities are not exactly secret. If that was the problem it would be in the story I think.

It is a well-known problem. [newsweek.com]. SpaceX lost forty of them a last year in a single event because of a solar storm flare-up during a critical part of the launch process (IIRC). The solar storm prevented them from reaching a stable orbit, and AFAIK they fell from the sky.

I'm pretty sure that the core problem here is that most satellites (with the exception of a few similar systems such as the SpaceX swarms) are designed to stay in orbit for a much longer period of time.

Over ten years (for example), solar activity will likely average out, and you can predict the lifespan reasonably well. But these satellites were designed to stay in orbit for just three years. If you pick the right three years, they might stay up for four years. If you pick the wrong three years, they might stay up for only two years. The shorter the lifespan, the more unpredictable the lifespan, unless you deliberately over-engineer them to have a lot of extra fuel just in case.

Re:

[dsgrntlxmply]

I just looked at the Wiki article on PAGEOS, launched in 1966, broken up in 1975, and fragments re-entering even as late as 2016. This one is an interesting limit case in surface area to mass: a 100 foot diameter, 125 pound Mylar balloon, orbit 4200 km. There was a recorded information number that one could call for satellite visibility, and DC area newspapers sometimes carried an article saying that a satellite would be visible and was uh ahem uh another in the Discoverer series (I knew of the CORONA pro

Re: Increased sun activity?

[Z00L00K]

If they are orbiting close to the edge of space then very small changes can have a great significance.

Re:

[cstacy]

That seems extreme. If solar events had that much effect, how do we still have satellites?

The solar effects are cyclical and we are only about 1/3 up the current rise, which is happening fairly fast. In a "few" years, it will indeed cause all of the satellites to fall down. All of them.

Re:

[Preston Pfarner]

Was Skylab [wikipedia.org] before your time?

Re:

[Motleypuss]

My guess it would be a low-fuel issue; the Earth has a fat enough arse already, and solar flares wouldn't embiggen the atmosphere. That'd be like putting lipstick on a pig, if you ask me, and it has scant relevance to satellites.

Unsurprising. Big antenna means high drag

[RightwingNutjob]

These things fly about the same altitude as starlink but have big giant radar dishes hanging off of them.

Remember folks, the antenna gain requirement for a 2-way radar is way higher than the antenna gain requirement for 1-way send and 1-way receive.

SAE all the way

[groobly]

Ok, I'll save the Europhiles some trouble: it's a US company, probably did their calculations in the English system of units, and forgot how many furlongs in a mile.

Capella's Earth

[brentstevenson]

Fascinating update on Capella's Earth imaging satellites. Their accelerated deorbiting highlights evolving space tech challenges. Curious about the reasons behind this

Capella's

[brentstevenson]

Fascinating read! Capella's satellites descending faster than anticipated highlights the complexities of space technology. A reminder of the challenges in orbital maintenance.