Launch Unit Standards for SmallSats Proposed
Aerospace Corporation Policy Paper proposes Launch Unit Standards for SmallSats
“The Aerospace Corporation’s Center for Space Policy and Strategy (CSPS) released a new policy paper today that explores the benefits of Launch Unit standards for smallsats during its Emerging Issues in Space Technology and Policy event at the Rayburn House Office Building in Washington, D.C. “More than 6,000 smallsats are expected to launch in the next 10 years, which is six times more than in the previous decade,” said Carrie O’Quinn, senior project engineer for Aerospace’s Research and Development Department. “As smallsats have increased in popularity, many stakeholders continue to advocate for cost-effective solutions in order to reduce cost and time-to-launch.”
Standardization is something that the shipping industry – here, speaking of ships plying Terra’s oceans – figured out beginning in the latter 1960s.
A cargo easily, and swiftly, moved from one rocket to another would drive down prices dramatically and quickly.
A company like SX could have an out-sized influence as the standards develop.
Not just smallsats (ie, the next step above cubesats), but even for full-scale multi-tonne satellites, IMO it would make sense to start developing a cubesat equivalent standard.
With the development of SHLVs (FH, Vulcan, NG) and even an UHLV (BFR), it would be useful to create a common standard for a multi-sat ejector for full scale sats. (For example, a standard for 1-tonne 1m cubes; and 5-tonne 4m cubes. With the ejectors able to handle up to, say, 4x of each standard 1-unit.) That way, ejectors and satellites can start to be developed, ready to go when cheap heavy launch is available.
A standard would be more than welcome. But it involves more than you suggest. You’re focusing on the form factor, but there are other requirements. Things like the propellents which can be used, both in composition and quantity, electronics being off until a certain interval after deployment, etc. They, and the standardized deployment system, are a really big deal. Without that, you’d have case-by-case reviews and negotiations for each individual CubeSat, involving the CubeSat team, the launch service provider, and possibly the primary payload owner. That would be extremely expensive compared to the cost of a CubeSat itself. (It’s far from trivial for much larger and expensive satellites.)
And simply cloning the CubeSat requirements for a larger size spacecraft isn’t clearly a good idea. The 10x10x10 cm form factor was picked for a reason; it nicely fits the standard PC/104 electronics cards. The right size and also what other standards are something that needs some thought. 100x100x100 cm and 1000 kg isn’t obviously the right choice, and the world is full of proposed standards that just didn’t catch on. I hope getting it right is what the Aerospace Corporation is working on and what will be in the report planned for release this August.
tl;dr – because cubes within cubes within cubes.
No, I get that a standard would also need to define how the satellite interacts with the ejector (and the ejector with the launch vehicle), tolerates specific forces and vibration modes, and flip-side to have specific weight distribution/balance. There would need to be a standard system of access through the ejector for prop loading, monitoring, etc. And etc… And etc… I get that the standard for large-sats would be vastly more demanding than for 1kg CubeSats.
And I get that many payloads simply wouldn’t be able to comply with such a standard and would need to be analysed on a case-by-case and launcher-specific basis.
But that’s the point of a standard. You exchange flexibility of design for greatly reduced time/cost of integration.
(And over time, reduced cost of development, thanks to a growing market of off-the-shelf standards-compatible sub-units, and frames through to full buses compatible with those sub-units. Another advantage of having a standard. It lowers the buy-in for specialty component makers, increasing competition and innovation in the market.)
The advantage of using a standard cube is that they can stack easily. (As happens with CubeSats, typically a 3U ejector loaded with anything from one 3U Subesat to three 1U sats. And 1x3U ejectors are often arrayed 1x3x3U.)
My reasoning is that I think it would probably be ideal to have the different scales overlap in a useful way. In which case, a scale based on the CubeSat standard might work out well for existing launchers.
For example, the volume taken up by a 3x3x3U array of CubeSat ejectors should be the size of a single 1U SmallSat ejector (which then gives you the 1U SmallSat scale. A bit over a foot.) Then a 3x3x3U array of SmallSat ejectors gives you the size for a 1U MediumSat ejector (a bit over a metre). Ditto MediumSats to LargeSats (around 4m). Note, ideally the 1U LargeSat standard ends up the full-width and half-length of all current 4m+ width payload fairings.
Such a standard allows a LargeSat customer to use an existing LV as a (2U) dedicated or (1U) secondary payload. But, if a SHLV or even UHLV launcher becomes available at lower price during the development of their satellite, they can switch over without significant cost/effort.
And that, IMO, is the reason why SpaceX should be pushing such standards now. FH is coming online. Similar size launchers should arrive in 2-3yrs. With BFR hopefully just a few years after that. Giving sat makers and customers time to get used to the new standards (and lower costs) would greatly benefit SpaceX once BFR exists and launch prices drop hard.
(Aside: It would be interesting if in a century or two, there is a standard scale of equipment, habitats, even ships which can be traced back to the ancient and forgotten 10cm CubeSat standard. Like the old joke about cars and rail-gauge being based on the width of two horses’ arses.)
(Aside 2: I’ve used the exterior size of an array of smaller ejectors as the basis for the size of the larger ejector, and from that the size of the larger cube. I’ve noticed that the proposed standards for 6U and 27U are multiples of 1U/3U, and so are not compatible with stacked 3U ejectors. IMO, that’s not a smart way to scale up. (Googling around, NASA’s own 6U standard, “ACES”, seems to be based on the scale of a pair of 3U ejectors, rather than just doubling the 3U Cube width. Hence offers >6U internal volume.))
It’s tricky, though, to come up with a standard that *everyone* likes (or will tolerate). The original P-Pod dispenser and the related dimensions for spacecraft inside were something that could be built easily without sophisticated manufacturing – but those loose tolerances mean that the spacecraft can “rattle around” in there during vibe. A dispenser like the Planetary Systems Corp CSD clamps the spacecraft in place when the door is closed, so vibe loads are more manageable (and predictable), but there’s a fairly tight tolerance problem on the parallelism and straightness of the tabs that get clamped. Spacecraft built for a P-pod won’t fit in a CSD and vice versa, notwithstanding that they are both nominally the same size.
This stuff is all resolvable, but unless there’s a “big dog” that drives a particular solution, there will still tend to be a plethora of choices. And the underlying problem is that you need to pick your dispenser a year and a half before launch, because you need that to build your spacecraft. That sort of gets in the way of “get on the next train through the station” model for small-sat launches – that next train may not have your kind of dispenser.
Hey Keith hear anything about the hot fire test at White Sands on the Starliner abort engines?