See: MLS Spaceport
MLS CONCEPT
L1 solar sails cannot be manufactured in space or on the Moon in time to avert a climate crisis—Earth manufacturing and launch is the only near-term option. Space-based geoengineering will require a large expansion of Earth-launch capacity, either by using larger rockets, or by a high launch rate of many smaller rockets.
The Mass Launch System (MLS) is a concept designed to sustain rocket launches every five minutes, year-round. This implies 288 launches per day, or 105,120 launches per year. The MLS payload total would be about 7,200,000 kg into MEO per day, or about 2.6 million tonnes per year. At this launch rate, with rockets reused thousands of times, fuel costs will dominate. A high launch rate will reduce the time to deploy space mirrors at L1.
Other long-term launch systems are possible, including space elevators and electromagnetic mass drivers. the MLS may enable humanity’s transition to a true space-faring species, with the solar system as our backyard.
MLS ROCKETS
The MLS Rocket concept is based on a scaled-down version SpaceX Starship technology (optimized for rapid relaunch), with reusable Raptor 2 engines, fueled by cryocooled liquid methane (LNG) and liquid hydrogen (CH4/LOX or methalox).
The impact of burning methane in the stratosphere must be evaluated, but CO2 (with H2O) may have smaller greenhouse forcing than only H2O from hydrolox rocket engines. The Hunga Tonga-Hunga Ha’apai volcano, which erupted January 15, 2022, injected a large amount of water vapor into the stratosphere. NASA observed "a small, temporary warming effect,” which was "not enough to noticeably exacerbate climate change effects.”
Giant rockets, such as SpaceX’s forthcoming Starship Launch System, can carry large payloads of up to 150,000 kg to LEO. Enormous size makes it challenging to rapidly relaunch heavy-lift rockets. The requirements to inspect 36 Raptor 2 engines, install a payload, stack the second stage, and refuel are much greater. For this analysis, two Starship launches per day are assumed (a higher launch rate may be possible).
MLS rockets should be optimized for rapid relaunch to MEO (2000 km) in less than two hours. A conceptual design could use five Raptor 2 engines in the first stage and a single Raptor 2 engine in the lifting body second stage. In this configuration, the MLS rocket could lift about 25,000 kg into MEO orbit – larger than the medium lift Atlas 5 or Ariane 5 rockets, or 17% of SpaceX’s Starship Super Heavy payload. MLS rockets would be designed for reuse (both the 1st and 2nd stages) a minimum of 1,000 times, with minimal servicing.
After launch, MLS rockets would fly back to the spaceport using grid fins and/or wings (the 2nd stage would orbit the Earth before returning). SpaceX has developed a concept to catch descending rockets with mechanical arms on launch towers (see animation). In the case of MLS rockets, both 1st and 2nd stage rockets would be caught on the same tower and restacked, ready for refuelling and a new payload of Pico Sails.
Assuming 83.5 million tonnes of space mirrors is needed at L1 (Fuglesang and Roy and Roy Youtube), the Mass Launch System would take 32 years to launch the required mass, compared 762 years using the Starship Heavy (at two launches per day). For the Starship Heavy to match the MLS, about 48 launches per day would be needed. [NB: With strong measures to reduce GHG emissions, the required mass of space mirrors at L1 may be reduced.]
COMPARISON OF STARSHIP HEAVY VS MLS LAUNCH SYSTEM
MLS R&D PRIORITIES
- Design and testing of robotic Pico Sails suited for L1 orbit.
- Payload stacking and bulk deployment of Pico Sails in orbit.
- Optimize booster and 2nd-stage orbiter for minimum fuel use.
- Selection of MLS spaceport site(s).
- Design MLS Rocket that can reused 1000s of times.
- MLS spaceport infrastructure: launch lines, refuelling, etc.
- Optimize MLS spaceport design for maximum launch rate.
- Assess MLS environmental, social, and economic impacts.
- Assess H2O vapor and CO2 rocket exhaust on stratosphere.
- Assess other uses for the MLS: space solar power, etc.
See: MLS Spaceport