another comment mentions starlink launches. If spaceX has 12000 satellites of their own that they need to send up, they can fill up a fair bit of unused capacity.

it sounds like they're essentially selling the opportunity to take the place of a starlink satellite in any given launch. if the customer cancels, no big deal - they'll just send the originally scheduled starlink satellite.

This looks very different from their Starlink launcher though and doesn't look like it could live above or below it either. Sun synchronous orbit is a pretty specific orbit too.

Yeah, the Starlink launcher was a pretty specific device designed around the Starlink satellites. The attachments shown in the attached link are the ESPA (EELV (Evolved Expendable Launch Vehicle) Secondary Payload Adapter) [1] rings. They work well for a variety of customers using it because you can put out a generic document for an interface and a box you need to fit within. The first dedicated rideshare program like this was the STP-2 mission. [2]

[1] https://en.wikipedia.org/wiki/EELV_Secondary_Payload_Adapter

[2] http://www.planetary.org/multimedia/space-images/spacecraft/...

Yeah, there aren't any plans to put Starlink satellites in SSO.

Maybe they're planning to fill vacancies with their own payloads that are not time sensitive?

Maybe, I'm not sure how useful a SSO is to SpaceX though.

Starlink sats can maneuver to different orbits. Their original test sats launched on an SSO launch.

They can but doing so reduces their operational life time so they'll want to minimize the amount of the thrust budget they expend on slot filling launches. As someone else pointed out their prices are high enough to cover the cost of a reusable launch with maybe half the ports filled so they're probably just playing the numbers game assuming there won't be a large coordinated drop out of customers. And those prices don't include the main top port which will likely cover a fair portion of the operation cost of the launch by itself.

The Starlink satellites are using hundreds of m/s raising and lowering their orbit. The sort of plane change you're talking about would take something close to a thousand, conservatively.

Not if it's a near-polar orbit. They'll probably need some in that orbit eventually.

They're only going up to 84 degrees inclination [0]. Not surprising there's an absolutely tiny number of customers that would use it if they added enough satellites to make 100% coverage.

[0] https://en.wikipedia.org/wiki/Starlink_(satellite_constellat...

Hmmm, that is a relatively high delta-v to change inclination that much (~1.5-2 km/s for a ~12-15 degree difference). On the other hand, if the shared payloads are light enough (and they very well may be, particularly if the launch is undersubscribed), the upper stage could do the orbital transfer and should have plenty of delta-v to do so (particularly with a droneship landing) considering F9 regularly does recoverable flights with many tons through 2.5km/s above LEO.

This seems likely. If customers drop out, they can just toss in a couple starlink sats.

Wrong orbit.

SSO != Starlink orbits.

They launched tintin A and B on SSO-A. They maneuvered to the correct orbits.

In their graphic, I count 7 15" ports and 8 24" ports, which at their before L-12 pricing is over $50 million. There's also the large port on top, which doesn't list pricing, but is presumably quite a bit more. The L-12 to L-6 pricing would be more as well. I believe their cost for a launch is something in the neighborhood of $30 million so they have quite a bit of margin to make money on this. Especially now that they're routinely reusing first stages and will probably use these flights as the final send-off for stages that are end-of-life.

It makes me wonder if they have any projects planned that they can throw in if there are empty slots.

Maybe that would help the economics quite a bit but I'm not sure what they'd be planning to use it for. SSO is a lot of earth observation (or sun observation for some specific SSO orbits that ride the terminator) and that doesn't really fit anything they're doing and there's already a couple companies in the low cost earth observation game.