Jon Goff has a very interesting post about the potential for justifying the private development of a LEO tug.
This is a key element of a LEO (and cis-lunar) infrastructure that NASA has ignored ever since the ignominious end of the disastrous Orbital Maneuvering Vehicle (OMV) program in the early nineties (another wonder of management from Marshall). We should have had one decades ago, but it looks like the private sector is going to have to make it happen. Once in existence, it has a number of other useful (and money making) applications, if NASA can start to be a good customer.
I might be missing something, but how does Iridium get servicing for $100 million?
Jon Goff’s post is part 2. Here is part 1.
The Iridium birds only cost $20m off the production line with an $8m launch cost.
As much as I am a proponent of servicing, this makes zero sense.
The Russian Parom orbital tug project still seems alive, although first flight has been pushed back to 2015.
http://www.russianspaceweb.com/parom.html
Of course I’ll believe it when I see it, considering the hype the Russians haven’t backed up with deeds over the last six years.
Dennis-
I’m pretty sure the costs you’re citing are the ‘one more’ cost if the production line were still going. If the satellites are still functioning and fuel is the only issue, then comparing the cost of a refueling tug to building a new craft AND a new production line is the valid comparison.
Dennis,
As others have pointed out a) you only get that per-unit price if you’re launching several of them at once–if you wanted to start the production line up again to replace just one satellite, and had to find a launch for it, I wouldn’t be surprised if the cost was a lot higher, and b) their entire constellation is getting old. Now, they are actively funding a follow-on constellation, but the point of my article is that with the time it will take to get that up and running, they might be able to benefit from servicing in the mean-time to keep their existing constellation healthy. I don’t think it’s crazy to think that a servicing mission can be cheap enough compared to relaunching all 66 birds to be worth consideration.
~Jon
I’ve long believed that the best business model for propellant depots and space tugs are delivering satellites from LEO to GEO (or at least GTO). This comes from an article I read in AvLeak a long time ago. It was one of the first articles that published hard numbers on the Russian Proton booster. The Proton comes in multiple versions. Based on the numbers in the article, the LEO only version of the Proton could put 20 metric tons into orbit. This was used to launch space station modules and other large payloads. Due to the high latitude of Tyuratam (Balkinour), the Proton could only put 2 metric tons in GEO because it needed a huge 18 metric ton upper stage to raise the orbit and lower the inclination. The same booster could deliver 5 metic tons to Mars, which goes to show the cost of lowering the inclination.
Even for launches from the Cape, you need a lot of delta-v to raise an orbit and lower the inclination for GEO. This means that to launch any given payload to GEO, you need a rocket capable of carrying not only the satellite but also the upper stage.
Now, picture this business case. You develop a reusable space tug to carry the satellite from LEO to either GTO (if the satellite has its own apogee kick motor) or to GEO. The satellite owner buys a rocket big enough to get the satellite to the tug where automatic rendezvous and docking occurs. Since he doesn’t need to buy the upper stage, the owner can buy a much smaller rocket (say a Delta II class instead of a Delta IV or Atlas V). The tug flies the transfer mission, releases the satellite, and then uses a combination of propulsion and aerobraking to return to the LEO parking orbit. It refuels from a depot and waits for the next mission. Depending of flight frequency and the time it takes to return the tug to the parking orbit, you might need more than one tug.
The satellite owner benefits from needing a smaller, less expensive rocket to get the satellite to orbit. Once the tugs are proven, they could provide lift services for a variety of satellites. They might also be able to save other satellites that were launched on conventional rockets but left stranded in unusable orbits by an upper stage failure (e.g. AEHF), something that seems to happen at least once a year.
Guys
Iridium thinks in this fashion. They think about production lines. The Iridium birds are hopelessly out of date in terms of the core data market as well as the voice system.
Also, in contrast to a GEO bird, the Iridium birds have a much harder environment regarding battery charge cycles and the thermal cycling of the solar arrays.
Also, without any provision for refueling, trying to get into their system is far more likely to lead to disaster than not.
You talk about it all you want, but the business case simply is not there.