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Probably is no breakthrough, other than solving a common problem with a reusable approach.

It is wasteful to have every satellite carry the weight of its own propellant and engines.

Having a single device that can deliver quite a few satellites to their orbit through clever planning and efficient fuel use could save significantly on weight, design, and launch, costs and complexity.

Well delivering multiple satellites could be a thing, it's still basically the same cost by mass, you're just splitting the monetary cost up among different customers. If you are delivering multiple GEO satellites, you also have to have them be the right place in their orbit, over their target, since they are stationary with respect to the earth (which is why you don't have to move your satellite TV dish). This means all your satellites for that bunch have to basically be near each other.

That also doesn't feel like it is reusable given this definition. I'd assume reusable means you can use it now, and then use it next month on a completely different mission. So let's explore that.

GEO satellites are also generally a lot bigger than your typical cubesat / nanosats that are all the rage in the bulk launcher configurations, because you need a big dish, and a lot of power to transmit and receive signals.

> It is wasteful to have every satellite carry the weight of its own propellant and engines.

Even if a satellite was delivered to GEO without using an engine, satellites need engines to do stationkeeping and keep their orbit, which is the critical factor for the operational lifetime of a satellite.

It's more wasteful to have to have your orbiting tug do an orbital rendezvous with a satellite in LEO (takes fuel to rendezvous), go to GEO (the normal cost, but more expensive since you have to carry the fuel for the return trip), then come back from GEO to LEO (takes fuel).

Following this delta-v map, it looks like it takes about 4000m/s of delta-v to go from LEO to GEO, then the same the other way back down.

https://external-preview.redd.it/U5iH7huE5qKth7ZFvipXt8vzaFO...

I don't know of any clever planning or efficient fuel use that can get over the raw amount of delta-v you'd need. Fuel use isn't really efficient, it's the engine that has to efficiently use the fuel, which is why I think there must be some breakthrough here.

Fuel also has to eventually be delivered up to the tug for refuel, so really it seems like all the mass savings is the dry mass of the 3rd stage.

I totally agree. You still need to get the fuel to space regardless of who is doing the propulsion work. Let's say that your tug is already on-orbit, how is the fuel going to be brought up? Would you not need to launch another spacecraft to bring you the fuel? How much would that spacecraft weigh?

Besides this, they would have to develop on-orbit refueling technology, as well as force the other spacecraft to use a bus that allows for rendez-vous and docking/proximity ops.

And also, how big is the market for satellite startups that are heading to GEO orbit? For now, it seems like it is just Astranis and GapSat.

We will be able to transport satellites up to 5000 lb in mass directly to GEO, which should be most of the market.

Almost every large GEO player is developing new, smaller satellites. We will also modify existing interfaces to allow for docking. Rendezvous and prox-ops is all on our side.

Who is "we"? Care to identify yourself? What existing interface are you talking about? Which GEO manufacturer is making 5000 lb spacecraft?

I can take a wild guess who "we" is, since Epic's young founder is Ignacio B. Montero and the nick is "ibmont".

"you got me"

That you don't know of it doesn't mean it doesnt exist :)

That's why I said "I don't know of any." I would love to know more if you know anything about what they're doing. As the only reference and information I could find about this company was literally this one paragraph (and I tried), it's not enough to say it won't work, but I think it's the company's job to explain how they will make good on their claims.

Are you involved with this company?

>it can take up to two years to qualify new satellite systems and can cost up to $30 million

That's the breakthrough. A sat manufacturer does not have to design, build and qualify their own propulsion system, but can pick this off-the-shelf part from Epic Aerospace.

The equivalent in electronics would be switched power supply modules in the 80s. When they were new, a PC/TV/hifi/other high tech product design team would design their own switched power supply, spending engineering time on that. Ten years later, they would just pick one from a supplier catalogue, and spend a lot less time on just integrating it.

> but can pick this off-the-shelf part from Epic Aerospace

And there are no existing off-the-shelf suppliers for satelite propulsion systems? That sounds unlikely.

No these systems tend to be custom due to cost, reliability and size constraints. More so for GEO satellites which tend to be the most expensive.

Is this even true?

https://gomspace.com/shop/subsystems/attitude-orbit-control-...

https://www.cubesatshop.com/product/ifm-nano-thruster/

https://www.vacco.com/space/chems-overview

That's what I was thinking too. Those are all for Cubesats tough, none of which have gone into GEO so far.[0]

[0]: https://space.stackexchange.com/a/22721

I didn't research every spacecraft but if you look at GTOSat, its intended orbit is GTO, so it won't really need the services of Epic since a rocket can place them there directly.

And if you look at the spacecraft, it doesn't seem to have any kind of meaningful propulsion system. https://space.skyrocket.de/doc_sdat/gtosat.htm

I'm sure the other spacecrafts have a similar design concept.

Operating in GTO is terrible for electronics.

And also, we could do GTO 2X cheaper than large rockets for even their nominal payload size. For smaller payloads, it's more like 10X.

So is your idea to have spacecraft go to LEO first instead of direct GTO? Is this an efficient use of fuel?

It's not a detour, you have to pass LEO to get to GTO. Instead of the rocket pushing it to GTO the tug will take over. So the rocket has more payload due to only having to go to LEO.

Props to the founder for his foresight choosing a name that will perfectly position them for an acquisition when Tim Sweeney decides he's ready to go head to head with Musk and Bezos.

Space tugs have been a topic of research for quite a while in the space community. A number of companies targeting the in-space space transport market over the last few years, e.g., [1][2]. There's also a recent YC alum targeting this [3].

Propulsion is itself a really hot topic in the NewSpace market the moment, ranging from tiny thrusters for precision attitude control of smallsats, to large systems for orbital transport. We recently published a review of smallsat thrusters, highlighting the rich spectrum of solutions being brought to market [4] (Disclaimer: I'm one of the co-founders at satsearch).

There's a lot of systems innovation that enabling fuel-efficient solutions to be developed. Particularly, there's a lot of progress being made on developing high-efficient electric propulsion. One of the trending areas is water-based propulsion, given that it's clean, non-toxic, storable, and also abundantly available in the Solar System [5].

With companies also look at building fuel depots to refuel spacecraft on orbit [6], there's a wide array of new solutions that are going to emerge for repeat use of tugs.

The traditional GEO market went through a massive dip last year [7], but there's renewed interest with the real prospect of small GEO missions materializing in the next 24 months. Another YC alum is targeting this market [8].

So in short, this is a really dynamic sector, going through a lot of changes at the moment. I'm eager to learn more about Epic, to see where they're carving a niche for themselves. Also, interesting to see YC's continuity in funding hardtech space startups.

[1] https://spacenews.com/airbus-to-challenge-ssl-orbital-atk-wi...

[2] https://www.atomosspace.com/

[3] https://momentus.space/rides/

[4] https://blog.satsearch.co/2019-07-10-cubesat-thrusters-an-ov...

[5] https://www.thespaceresource.com/news/2019/2/propelling-dema...

[6] https://www.orbitfab.space/

[7] https://spacenews.com/amid-geo-downturn-launch-operators-loo...

[8] https://www.astranis.com/