NASA hopes to launch the most powerful rocket ever built before the end of August. Let’s take a look at the Space Launch System (SLS), what’s used to set important launch dates, and how you can watch the uber science rocket take off for free.
The SLS is a truly monstrous rocket.
When fully stacked with its Orion crew module, it stands about 320 feet tall, the equivalent of 33 Lady Dimitrescus, and strikes an imposing, lonely figure on the launch pad at NASA’s Kennedy Space Center.
Its first stage, which makes up the bulk of the rocket, is powered by four refurbished shuttle-era RS-25 engines aided by two solid-fuel thrusters in place, which together are capable of generating a staggering thrust of 8 .8 million pounds during launch. For context, the Saturn V rocket that launched astronauts to the Moon in the 1960/70s generated only 7.5 million pounds of thrust.
The upper section of the SLS also houses a motor specifically designed to give the rocket’s payload, including its crew capsule, the final push needed to break free from low-Earth orbit and get it on course to meet the Moon.
In the coming years, NASA and its partners want to harness this power to help in their ambitious mission to return astronauts to the Moon as part of the Artemis Program. NASA’s key goals with Artemis will be to establish a permanent human presence on the Moon where humanity can explore the surface of Earth’s natural satellite, while developing the technologies needed to safely send humanity to Mars.
This ambitious plan would require a huge amount of resources to get it out of Earth’s atmosphere and into lunar orbit, which is where the SLS’s impressive lift capabilities come into play.
However, despite the investment of billions of dollars and more than a decade of planning, there is no guarantee that the first launch of the rocket will be a success. Developing the SLS was a monumental engineering and scientific challenge, and it hasn’t always gone smoothly.
In the lead-up to launch, testing of the rocket’s many components raised numerous design issues that had to be resolved before NASA could even consider using the rocket.
Countless setbacks pushed the rocket’s first launch back from an ambitious 2017 target to August 2022. That’s a huge delay. Also, as reported by CNBC, NASA Inspector General Paul Martin estimated in a congressional meeting earlier this year that each SLS launch could cost US$4.1 billion. That’s more than the cost of the entire 20-year lifetime of the Cassini mission.
In short, it would be very, very inconvenient if NASA’s extremely expensive, long-awaited, and operationally unproven rocket suffered a catastrophic failure during its maiden flight.
The stakes are high
The stakes are high, and last month NASA revealed it would attempt to launch its first SLS rocket, carrying an unmanned Orion capsule, as soon as August 29 from the Kennedy Space Center in Florida.
If all goes well, the SLS will catapult the crew capsule, along with its European-made service module, into space on an ambitious 38- to 42-day test mission known as Artemis 1.
During the ascent through Earth’s atmosphere, both the launch vehicle and its precious Orion payload will be subjected to extreme temperatures, vibrations and other disruptive pressures.
The capsule will then be forced to survive the frigid environment of space for weeks on end as it lies 280,000 miles from Earth, further than any crew-worthy spacecraft has ever flown before to finally face a fiery re-entry.
This gauntlet will test the performance of the SLS and measure Orion’s worthiness to carry a human crew into lunar orbit and eventually return safely to Earth.
NASA’s Super Heavy Moon Rocket: The Space Launch System
However, there are a number of factors ranging from the mundane to the technical that could prevent the rocket from launching during the two-hour window on August 29. For example, bad weather could easily screw up a launch, or there could be unforeseen safety issues. A last-minute technical problem detected during pre-launch checks could also ruin many scientists’ day.
In light of this, NASA has announced a slew of backup launch windows, including one on September 2nd and another on September 5th. If by some unfortunate chain of events the rocket is still tethered to the ground after these dates, then the agency has prepared more dates in two weeks after that, two weeks off that extend until December 23.
A great deal of planning goes into selecting these dates, not only for the sake of the rocket, but also for the safety of the Orion capsule that will be the focus of most of the multi-week mission.
For example, the launch can only take place when the Earth and the Moon are in the right position to each other to initiate the transfer burn required to place the capsule in the distant lunar orbit required for the mission.
Mission planners also had to calculate a launch date, and therefore a trajectory, that would allow the spacecraft to avoid falling into the Moon or Earth’s shadow for more than 90 minutes at a time. This is vital as the solar panels on the Orion spacecraft must be bathed in sunlight to generate electricity and provide a habitable environment for a future crew.
He wants to fall
The flight must also be planned in a way that allows the capsule to dip briefly into the Earth’s atmosphere when it returns to slow down before climbing back into space, like a skipping stone on the surface of a lake.
This fantastic drop reduces the heat build-up from atmospheric reentry and reduces the g-forces that the Orion crew would experience. It also allows NASA to more accurately predict where the capsule will end up splashing up on the coast of San Diego.
NASA took all of these criteria into account when selecting 8:33 a.m. EDT on August 29 as the start of the first launch window.
Although it has yet to be announced, NASA is sure to live stream the historic launch and subsequent coverage of the Artemis mission on its NASA TV streaming channel. In the meantime, be sure to enjoy live views of Earth captured from the outer hull of the International Space Station courtesy of the ISS HD Earth Viewing Experiment.
Anthony Wood is a freelance writer for IGN.
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