Clarity is designed for a GSD (ground sample distance) of 10 cm. Generally the industry uses resolution<>GSD interchangeably. Agree it's not the true definition of resolution. But I'd argue the diffraction limit is an incomplete metric as well, like how spatial sampling is balanced with other MTF contributors (e.g. jitter/smear). For complete metrics, we like 1) NIIRS or 2) % contrast for a given object size on the ground (i.e. system MTF translated to ground units, not image-space units).

The main performance goal for us was NIIRS 7, and we decomposed GSD/MTF/SNR contributors optimized for affordability when we architected the system

I'm AyJay, Topher's co-founder and Albedo's CTO. We'll actually be publishing a paper here in a few weeks detailing how we got 3-axis torque rod control so you can get the real nitty gritty details then.

We got here after stacking quite a few capabilities we'd developed on top of one another and realizing we were beginning to see behavior we should be able to wrap up into a viable control strategy.

Traditional approaches to torque rod control rely on convergence over long time horizons spanning many orbits, but this artificially restricts the control objectives that can be accomplished. Our momentum control method reduced convergence time by incorporating both current and future magnetic field estimates into a special built Lyapunov-based control law we'd be perfecting for VLEO. By the time the issue popped up, we already had a lot of the ingredients needed and were able to get our algorithms to control within an orbit or two of initialization and then were able to stay coarsely stable for most inertial ECI attitudes albeit with wide pointing error bars as stated in the article. For what we needed though, it was perfect.

Ultimately it's about the ballistic coefficient. You want high mass, low cross-sectional area, and low drag coefficient (Cd). With propulsion for station-keeping, it's challenging to capture the VLEO benefits with a regular cubesat. That said, there are VLEO architectures different than Clarity that make sense for other mission areas.

Yes it's a big contributor. The atmosphere in VLEO behaves as free molecular flow instead of a continuous fluid.

First - they never want to use someone else software framework again (an early SW architect decided that would accelerate things but we ended up re-writing almost all of it) and it was all C++ on the satellite. We ran linux with preempt_rt.

We wrote everything from low level drivers to the top level application and the corresponding ground software for commanding and planning as well. Going forward, we're writing everything top to bottom, just to simplify and have total ownership since we're basically there already.

For testing we hit it at multiple levels: unit test, hardware in the loop, a custom "flight software in test" we called "FIT" which executed a few different simulated mission scenarios, and we tried to hit as many fault cases as we could too. It was pretty stressful for the team tbh but they were super stoked to see how well it worked on orbit.

A big one for us in a super high resolution mission like this is the timing determinism (low latency/low jitter) of the guidance, navigation, and control (GNC) thread. Basically it needs execute on time, every cycle, for us to achieve the mission. Getting enough timing instrumentation was tough with the framework we had selected and we eventually got there, but making sure the "hot loop" didn't miss deadlines was more a function of working with that framework than any limitation of linux operating well enough in a RTOS fashion for us.

Moving fast to make launch, we had missed a harness checkout step that would’ve caught a missing comms connection into an FPGA, and it was masked because our redundant comms channel made everything look nominal.

On orbit, we fixed it by pushing an FPGA update and adding software-level switching between the channels to prove the update applied and isolate the hardware path — which worked. Broader lesson, it is possible to design a sw stack capable of making updates to traditionally burned-in components.

From my perspective, the number one reason we had a well functioning satellite out of the gate is my philosophy of testing "safe mode first". What that means is in a graduated fashion, test that the hardware and software together can always get you into a safe mode - which is usually power positive, attitude stable, and communicative. So our software integration flows hit this mission thread over and over and over with each update. If we shipped a new software feature, make sure you got to safe mode. If we found a bug that prevented it, it's the first thing to triage. We build out our pipelines to simulate this as much as we could and then ran it again on the development hardware and eventually would load a release onto flight once we were confident this was always solid. If you're going to develop for space, start here.

At least it wasn't "learns", like "we had five learns from the project". Like, say, "ad spend". There's already a noun form of a verb, it's called a gerund: "ad spending".

I work near space but not in space. I'm not sure I understand your process here. I see 2 possibilities: 1. You bought something the manufacturer spec lied about. While true we often validate specs, our terrestrial stuff is a lot cheaper so we can afford the spares. That said, if we buy something that doesn't meet the spec, you best believe we're taking the actions necessary. 2. This was built or designed inhouse, and the requirements didn't flow down correctly. That's also not great.

To be honest, postmortems (especially from startups) toe a fine line of scaring off investors, and this write-up seems a bit too glaze-y. I'm very happy for you that so much worked so effortlessly post launch, but that's more a success story than a postmortem. I'd like to see more of the root cause analysis for the issue, both technically and programmatically.

> Perhaps the test wasnt long enough?

Small (ok, maybe not so small) fortunes are spent on accelerated testing in the space domain. The test and validation gear is immense, using it is extremely expensive (especially when you get to full scale) and access is limited. They may well have been limited to that week for many reasons and conditions being what they are there is a fair chance that the space environment caused an issue that would have shown up if they had had a much longer test but that if there is no trend or if instrumentation is not sufficient simply doesn't show up at all.

For instance, if you're not measuring current into each and every actuator, or if the resolution at which you are sampling is too low then there may well be a developing issue that you are completely blind to.

Yeh, it's an interesting project but the AI writing style was exhausting to read, and didn't fill me with confidence in the company.

It’s not the engineers who have the money or the control of company decisions. The engineers might make recommendations to their PMs and director of whatever program, but when considered against the myriad other bus options in LEO, the decision makers might be scared off by this writing and choose a less risky bus and accept the worse imaging performance or performance degradation in whatever other payload they integrate.

> Tone policing isn’t helpful.

Yes it is, these are YC alums. A significant portion of that program is learning how to pitch to investors. Are you saying that YC wastes this effort? The goal of this post might be to recruit engineers to hire, but it is public facing and part of their image that anyone might read, including future customers. It doesn’t help to recruit good engineers but be unable to sell because the industry expects strict professionalism.

Ok, good luck with that, that's a tough environment for such sensitive stuff. Unfortunately your application seems to be so advanced that you can't get away from having high speed and super integrated stuff on board there otherwise you'd be more intrinsically safe against such issues. The fact that it worked well initially and then degraded until it failed is a strong indicator of the kind of process that caused the failure but unfortunately that still leaves a whole slew of options on the table.

Much good luck with this, those are hard problems to solve but you guys got so much right on the first try that you're probably ahead on your schedule now so you may have the time and the budget to get this right. I've visited the ESA open day a while ago and have seen the guts of what goes into satellite manufacture (not the most recent stuff, just what they had on display) and what struck me is that the degree of rigor that goes into designing stuff that is in the most literal sense out of reach for fixes or diagnostics requires simulating the environment the device will operate in to the best of their ability. This results in autoclaves that you can walk around in and various radiation sources to be able to test how the devices respond to space conditions.

Your manufacturer/supplier will probably come away from this effort with as much knowledge and improvement items as you do. Given the short time to failure I'm not so sure redundancy alone would have been a sufficient fix, but that's obviously bystander perspective, you know far more than I do. But it certainly is an amazing and interesting project.

Ah, safe for others, not for the telescope. Thanks, I did not consider that option.

Looking forward to more launches! Thank you

So, a set of standard software RPCs (remote procedure calls) and APIs (application programming interfaces) and not another electrical signalling standard. Got it.

Thanks for the correction.

So, I guess the next question is what are you folks actually using at the electrical signalling level to talk? (If you are not allowed to say, I understand.)