The Space Launch System (SLS) is an aerospace launch vehicle designed to carry crews and cargo on deep-space missions onboard NASA's Orion spacecraft. SLS, which is the first exploration-class launch vehicle built since the Saturn V, offers greater payload mass, volume capability and energy capabilities than current launch vehicles. Considered the most powerful rocket ever built, the Space Launch System has a total thrust greater than that of the Saturn V, which puts the SLS into the super heavy-lift launch vehicle class of rockets.
Heavy lift is essential for deep-space human exploration. Mars landings, for instance, would require at least the equivalent mass of the International Space Station to be launched from Earth, which took 10 years and 30 missions. With a 130 metric-ton lift capability, the SLS could reportedly accomplish this in just six or seven flights, significantly reducing the missions’ complexity and increasing their cost-effectiveness.
The first SLS rocket is expected to be delivered to NASA’s Kennedy Space Center for its initial launch in 2019. It is designed to evolve into increasingly powerful configurations and open new possibilities for payloads. The SLS is integrating hardware and manufacturing techniques developed for the Space Shuttle and other exploration programs with new designs and new technologies to help reduce development and operations costs.
The first SLS rocket, the Block I configuration with a 70-metric-ton (77-ton) lift capability, will be powered by twin boosters and four RS-25 engines. (The RS-25 engine powered the Space Shuttle.) The next planned evolution, Block 1B, would use a more powerful exploration upper stage to enable more ambitious missions and a 105-metric-ton lift capacity; a later evolution, Block 2, would add two advanced solid or liquid propellant boosters to provide the 130-metric-ton (143-ton) lift capacity. In each configuration, SLS will continue to use the same core stage and four RS-25 engines.
The Block 1 configuration of SLS will be 322 feet tall, higher than the Statue of Liberty; will produce 8.4 million pounds of thrust at liftoff, the equivalent of 13,400 locomotive engines; and will be capable of carrying 154,000 pounds of payload, about the same as 12 full-grown elephants. Both Block 1B and Block 2 will be more than 363 feet tall, taller than the Saturn V rocket. Block 2 will provide 9.2 million pounds of thrust at liftoff and weigh 6.5 million pounds.
The SLS’ upgrades will boost its capability to lift astronauts and hardware beyond low Earth Orbit (LEO). (Most scientific satellites and many weather satellites are in an LEO, which has an altitude between the Earth's surface and 2,000 kilometers (1,200 miles), along with an orbital period of about 84 to 127 minutes.) Block 1 is aimed at lifting a payload of 70 metric tons to LEO, and this will be increased with the Block 1B’s debut. Block 2 will replace the Shuttle-derived boosters with advanced boosters and is planned to have a LEO capability of more than 130 metric tons.