ITS and new economics of satellite launch
In one of the previous posts, I have argued why SpaceX should use ITS SSTO as a next step to replace and retire Falcon family or rockets. But if that happens, would would change for typical satellite owner?
ITS without BFR (booster stage) cannot go above LEO. So by its nature it could not launch any satellite to GEO transfer orbit or out of Earth gravity well. Most likely it would not even be able to launch to Sun-Synchronous Orbit (SSO). It would be barely able to launch to LEO with just 1% of the usable payload. So why would satellite operators even consider launching SSO or GEO satellites on ITS?
First, ITS brings completely different economics of space launch. LEO is not a place. It is a family of orbits. But ITS can be viewed as a 1st stage that launches regularly and brings the payload into a standard drop-off orbit. So satellite either needs to provide its own propulsion to bring itself to the target orbit, or space-tug must act as the second stage to fetch the payload and push it to the target orbit. And then come back to drop-off orbit for refueling and new payload. Such orbital transfers with large delta-C changes are possible only with solar-electric propulsion (SEP), and can take several months to complete. New SEP enabled satellites typically needed between four and six months for 1800m/s deltaV change from transfer orbit to GEO. So a typical space-tug mission could easily take one to two years to complete.
But ITS due to its unparalleled cargo space under 9m body frame will enable launching much larger solar panels even without special solar panel deployment changes. This directly translates to higher power and higher thrust that can shorten transfer duration. So space tugs will be able to provide needed delta-V in shorter period of time. Since current launch campaigns typically suffer from months of delays for various reasons, six month transfer to the target orbit might be acceptable. In that scenario, launch to LEO drop-off orbit would be quite low cost (lets say three million for 10t of cargo), but transfer to the target orbit (such as GEO) would be costly since it would allocate a space tug for one year. But still such transfer could be accomplished for less than 20 million USD per mission.
SEP propulsion would not need be optimized for extremely high specific impulse. Even Hall thrusters with Isp of 2000s would have good enough mass fraction for most transfers. But the space tug would require design capable of going to LEO and providing enough thrust to spiral out from LEO despite drag from large PV panels and half of the time spent in the Earths shadow.
Additional risk for satellite payload is related to much longer period that would be spent crossing Van-Allen belts, even compared to current SEP satellites, since they are initially set to transfer orbit which passed through the belts rather fast during the raising orbit from GTO to GEO.
But the main advantage of this architecture is that satellite operator can perform in-space checkout of the satellite at the drop off orbit, BEFORE space tug captures it and initiates orbital transfer. If any unsolvable problems are found, ITS can re-capture the satellite, bring it into its cargo-bay and return it to Earth. That would represent a revolution in the way how satellites are built and tested, since they could be returned to Earth after inspection. For example, imagine a case where upcoming James Web Space Telescope (JWST) would be sent to drop off orbit for a trial run, checking of all of the systems and then returning it back to Earth after a trial run. For just three million USD? On a project that costs three orders of magnitude more?
In this architecture a drop-off orbit could be reached frequently (once a week) and cost-effectively (around 300USD/kg), which would no longer require dedicated missions and more like allocating a cargo slot on some launch, similar to airline business model or Rocket Lab launch booking. Around that drop-off orbit (or several of them), whole new infrastructure could be built (depots, servicing satellites, tugs of different sizes, commercial space stations). In other words, drop-off orbit would become analogue of airport terminal on the edge of space. And ITS SSTO would be the shuttle line between Earth and the new spaceport terminal in LEO.
ITS without BFR (booster stage) cannot go above LEO. So by its nature it could not launch any satellite to GEO transfer orbit or out of Earth gravity well. Most likely it would not even be able to launch to Sun-Synchronous Orbit (SSO). It would be barely able to launch to LEO with just 1% of the usable payload. So why would satellite operators even consider launching SSO or GEO satellites on ITS?
First, ITS brings completely different economics of space launch. LEO is not a place. It is a family of orbits. But ITS can be viewed as a 1st stage that launches regularly and brings the payload into a standard drop-off orbit. So satellite either needs to provide its own propulsion to bring itself to the target orbit, or space-tug must act as the second stage to fetch the payload and push it to the target orbit. And then come back to drop-off orbit for refueling and new payload. Such orbital transfers with large delta-C changes are possible only with solar-electric propulsion (SEP), and can take several months to complete. New SEP enabled satellites typically needed between four and six months for 1800m/s deltaV change from transfer orbit to GEO. So a typical space-tug mission could easily take one to two years to complete.
But ITS due to its unparalleled cargo space under 9m body frame will enable launching much larger solar panels even without special solar panel deployment changes. This directly translates to higher power and higher thrust that can shorten transfer duration. So space tugs will be able to provide needed delta-V in shorter period of time. Since current launch campaigns typically suffer from months of delays for various reasons, six month transfer to the target orbit might be acceptable. In that scenario, launch to LEO drop-off orbit would be quite low cost (lets say three million for 10t of cargo), but transfer to the target orbit (such as GEO) would be costly since it would allocate a space tug for one year. But still such transfer could be accomplished for less than 20 million USD per mission.
SEP propulsion would not need be optimized for extremely high specific impulse. Even Hall thrusters with Isp of 2000s would have good enough mass fraction for most transfers. But the space tug would require design capable of going to LEO and providing enough thrust to spiral out from LEO despite drag from large PV panels and half of the time spent in the Earths shadow.
Additional risk for satellite payload is related to much longer period that would be spent crossing Van-Allen belts, even compared to current SEP satellites, since they are initially set to transfer orbit which passed through the belts rather fast during the raising orbit from GTO to GEO.
But the main advantage of this architecture is that satellite operator can perform in-space checkout of the satellite at the drop off orbit, BEFORE space tug captures it and initiates orbital transfer. If any unsolvable problems are found, ITS can re-capture the satellite, bring it into its cargo-bay and return it to Earth. That would represent a revolution in the way how satellites are built and tested, since they could be returned to Earth after inspection. For example, imagine a case where upcoming James Web Space Telescope (JWST) would be sent to drop off orbit for a trial run, checking of all of the systems and then returning it back to Earth after a trial run. For just three million USD? On a project that costs three orders of magnitude more?
In this architecture a drop-off orbit could be reached frequently (once a week) and cost-effectively (around 300USD/kg), which would no longer require dedicated missions and more like allocating a cargo slot on some launch, similar to airline business model or Rocket Lab launch booking. Around that drop-off orbit (or several of them), whole new infrastructure could be built (depots, servicing satellites, tugs of different sizes, commercial space stations). In other words, drop-off orbit would become analogue of airport terminal on the edge of space. And ITS SSTO would be the shuttle line between Earth and the new spaceport terminal in LEO.
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