[AR] Re: Pilot, ALASA, and cubesat launch (was Re: some interesting developments)

  • From: Valtteri Maja <valtteri.maja@xxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Wed, 6 Jan 2016 23:11:40 +0200

6.1.2016, 22.11, Henry Spencer kirjoitti:

commercial ALASA was that you'd need really high launch volume to justify a privately-owned F-15. And when looking at the cubesat market, you have to remember that 90%+ of it is poverty-stricken student projects that *want* to fly as cheap or free secondary payloads.

When you start trying to build nanosats with serious payloads and solid engineering and paying customers, you discover rather quickly that you want a somewhat larger volume than a 3U cubesat, and preferably a less elongated one too. If you're trying to accommodate paying customers, not just today's but also tomorrow's, I'd suggest looking at the "12U cubesat" specs of outfits like <http://www.planetarysystemscorp.com/> (there is no industry-wide standard beyond 3U). That's circa 22x22x35cm, 20kg+ (*not* 20x20x30 and 12kg, as you might think from that misleading "12" number -- even the 3U cubesat standard actually allows more than 3.0kg).

And don't forget that cubesats are built to fly in deployers that can weigh as much as they do. You can undoubtedly reduce that some, but not to zero -- it's not a matter of just a little mounting ring, not if you want to launch standard cubesats. (And for that matter, if you read the specs from people who build things like those rings, you find that their small ones are noticeable chunks of hardware with nontrivial mass -- they don't scale down linearly.)

In short, I think a realistic commercial "cubesat" launcher *should* be aiming at something close to ALASA's payload. I don't think you're going to make it pay at 3kg.

Henry

I've been toying with this idea for quite a while, but the last stage and the payload have a lot of potential for shared hardware (and software too). In larger rockets, it's not worth the trouble, but in a smaller scale it starts making a lot of sense. This is of course if we assume the upper stage is not a dumb-as-possible spinning solid with an egg timer release.

For example the upper stage has telemetry (radios, antennas), attitude and position sensing (gyros, accelerometers, star cameras, GPS), and it also has to have some kind of batteries, and of course a computer. If your payload is 3 kg, and you don't need to implement all that in the payload since the platform provides it as part of the upper stage, then you have more mass left - and also more money left to worry about the actual purpose of the mission. If the payload doesn't need to turn around a lot, you don't even necessarily need to separate it from the upper stage, again saving a lot of mass.

Of course then you can say that integration is really hard, better that everyone brings just their own computer and sensors and batteries. But you could provide open interfaces and standard boards. One would have to do some surveys to find out where the most synergies lie.

For example Clyde Space already provides cubesat platforms and components, IIRC price class is some tens of thousands of dollars. http://www.clyde-space.com/cubesat_shop/qb50

If you used that kind of relatively standard hardware to guide both the rocket and the payload, then you wouldn't need to develop everything double. The launch provider could have more customers and yet the customer could use a larger portion of their budget for the launch.

- Valtteri Maja

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