Y Combinator Startup Podcast
00:03:20 · Philip Johnston
[00:03:20] S0: Data centers makes a lot of sense to be the first thing you do because you don't need to reenter a product. So with things like, asteroid mining or with manufacturing in space or space hotels, they require this very expensive reentry process. Initially, what we actually started doing was space based solar. So huge solar panels, and then you beam that power down, and it's it's a concept from, I think, like, the sixties. Even Asimov in the forties was writing about it. The problem with space based solar is you actually lose 95% of the energy in transmission from space to earth. And so for the first two months of the company, that was literally what we're doing. We were called Lumen Orbit because of that that reason, luminosity in orbit in orbit. We were thinking, okay, once we get that power down, what are we gonna be using it for? And even back in '23, most new energy projects were being built for data centers. So we were like, okay, well, either directly or indirectly, this power is gonna go into data centers. Let's rerun those numbers. So initially, we'd run the numbers to know what's the launch cost breakeven that makes sense for space based solar, and we'd come to a number of, like, $50 a kilo. So then we rerun the calculations. We were like, okay, let's spend a month figuring out what would the launch cost breakeven need to be to make data centers in space breakeven. And we came to a much closer to reality number of $500 a kilo, and that's what we think currently that the breakeven launch cost is. And so then we rapidly pivoted the company towards that.
00:04:38 · S3
[00:04:38] S3: So, Philip, you launched StarCloud one in November 2025, and that was a real emotional moment. Like, can you walk us through what that was like?
00:04:48 · Philip Johnston, S3
[00:04:48] S0: Yeah. I mean, it was incredible. So just to tell people a bit about StarCloud one. So we'd set this launch date, you know, eighteen months in the future, and we initially started with something quite unimpressive. Like, we were gonna fly some NVIDIA jets and chips. They've been flown in space before, and we were gonna try and do some new new workloads on there. Yeah. So it was Adi that came on and said, no. We need to do something way way cooler than that. And, we actually ended up putting five GPUs on there, two... Three from NVIDIA, two from ARM, but the most interesting one was this NVIDIA h 100. We did some crazy things. Like, for example, you have to put it through thermal cycling, and we didn't have time to... We, like, book the the vacuum chamber, the thermal and vacuum chamber. And... But we needed to know, okay, if we heat up this phase change material and cool it down, heat it up and cool it down, is it gonna crack anything? And so at like 5AM, the day we had to ship it down, we're working through the night. Adi and Ezra are like dunking this thing in an ice bath to cool it down. Oh my god. And then we pull it out of the ice bath and I'm like, are you sure it's gonna be fine with the electronics? They're like, don't worry about it. Yeah. It's totally fine. They pulled it out of the ice bath, then we had these, like like, hair dryers to heat it up and melt all the wax. Yeah. Like, or like hot air guns, and then we're dunking it back in the ice bath. It is a miracle that it works, to be honest. [00:06:03] S3: You can just do things.
00:06:03 · S3, Philip Johnston, S4, S2, S1
[00:06:03] S3: You can just do things. [00:06:04] S0: You can just do things. Yeah. This is this is the kind of thing you can do as a startup because we actually had a quote from one of the primes on what it would cost to do StarCloud one, they said 75,000,000 to a $100,000,000. I mean, [00:06:13] S4: we did the [00:06:14] S0: whole of StarCloud two, including the launch for $2,000,000. Yeah. So, yeah, leading up to the to the launch, I mean, we we got the most incredible separation video. I think we're gonna play it [00:06:23] S2: now. Starcloud one, separation confirmed. [00:06:26] S0: So half the time as it deploys, it will be behind the shadow of the earth and you don't see anything. The other half of the time, it will deploy not into the silhouette of the earth. And so, I mean, it just is the most perfect, like, deployment video I've ever seen. And this was played by Jensen as he walked on stage at the GTC conference this year. This five story tall, like, screen behind him playing the StarCloud one separation [00:06:48] S3: video. Amazing. [00:06:50] S0: So, no, it was the most incredible feeling seeing this, deploy. [00:06:53] S1: Where was the team for this? Did you all, like,
00:06:53 · S1, Philip Johnston
[00:06:53] S1: Where was the team for this? Did you all, like, [00:06:55] S0: go team down. Yeah. There was only, 12 in the team at the time of StarCloud one launch, so we took the whole team to Florida. And we had, like, a 100 friends and family, investors. We... Some of our team brought their family and kids down, and, like, it was a real nice, really nice day. We're gonna release a a behind the scenes video of some of the, like, family moments in that, launch. [00:07:15] S1: How long was it from, like, when the rocket lifted off until the thing deployed, until you powered it up and were able to verify the thing actually worked?
00:07:22 · Philip Johnston
[00:07:22] S0: Yeah. So it lifted off. We were all on what they call the banana bleachers. It's like the famous from the Apollo era, but it was in the middle of the night. So it lifted off at around midnight. And then at 1AM, they closed the bleachers and everyone had to get on a bus and leave. And we're like, oh, shit. I thought we were gonna, like, be able to watch the deployment. And then I'm sitting in the back of a cab, like watching the live feed on spacex.com literally. And I was like, oh my god. It's deploying. I can't... It's deploying. And then it took about twelve hours to make first contact, which is not bad actually. It usually takes at least twenty four hours to get first contact. And then it's like a two week commissioning period, and we had a whole bunch of software issues we had to work through. Like, it kept re... The the whole satellite kept restarting every two hours. And what was happening is one of 20 different, like, failure, like triggers was triggering, And we didn't know which one it was, and we can only get a ground station pass every, like, at least every hour and a half, maybe longer. And so we had to manually turn off each one, turn back on everything else, and wait for a ground station pass to know which one it was. So that took, like, know, that took, like, three days just to figure out that software issue. And then, yeah, two weeks after that, then we started commissioning and turning on all the different payloads, and then we trained the first model, ran the first version of Gemini. We did the first fine tuning of a model on... In orbit, Did the first high powered inference on on satellite imagery and all this kind of stuff.