NASA hopes to launch the most powerful rocket ever created before the end of August. Let’s take a look at the Space Launch System (SLS), what goes into setting the all important launch dates, and how you can watch the scientific uber missile lift off live for free.
The SLS is a truly monstrous rocket.
When fully stacked with its Orion crew module it stands around 320 ft tall — the equivalent to 33 Lady Dimitrescus — and strikes an imposing solitary figure on the launch pad of NASA’s Kennedy Space Center.
Its first stage — which makes up the bulk of the rocket — is powered by four refurbished RS-25 shuttle-era engines aided by two gargantuan solid fuel strap-on boosters, which together are capable of generating a staggering 8.8 million pounds of thrust during launch. For context, the Saturn V rocket which launched astronauts to the moon in the 1960/70s generated just 7.5 million pounds of thrust.
The upper section of the SLS also houses an engine designed specifically to give the rocket’s payload – including its crew capsule – the final push needed to break free of low-Earth orbit, and set it on a course to rendezvous with the Moon.
In the coming years, NASA and its partners want to harness this power to aid in its 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 on to Mars.
This ambitious plan would require a huge amount of resources to be hefted out of Earth’s atmosphere and into lunar orbit, which is where the impressive lift capabilities of the SLS come into play.
However, despite the investment of billions of dollars and over a decade of planning, there’s no guarantee that the rocket’s first launch will be a success. The development of the SLS was a monumental engineering and scientific challenge, and it hasn’t always gone smoothly.
In the run up to launch, testing of the rocket’s many components threw up numerous design issues that had to be addressed before NASA could consider putting the rocket to use.
Countless setbacks led to the rocket’s first launch being pushed back from an ambitious 2017 target all the way to August 2022. That’s a hefty delay. Furthermore, as reported on by CNBC, NASA’s Inspector General Paul Martin estimated in a meeting with congress earlier this year that each launch of the SLS could cost an eye watering $4.1 billion US dollars. That’s more than the entire lifetime cost of the 20 year Cassini mission.
In short, it would be very, very awkward if NASA’s extremely expensive, long awaited, and operationally untested rocket were to suffer a catastrophic failure during its maiden flight.
The stakes are high
The stakes are high, and last month NASA revealed that it would attempt to launch its first SLS rocket — complete with an uncrewed Orion capsule — as soon as August 29th, 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 – 42 day testing mission known as Artemis 1.
Over the course of 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 ranges 280,000 miles from Earth — further than any crew-worthy spacecraft has ever flown — before finally braving a fiery re-entry.
This gauntlet will test the performance of the SLS, and gauge Orion’s worthiness to bear a human crew into lunar orbit and, eventually, safely back to Earth.
However, there are a range of factors running from the mundane to the technical that could prevent the rocket from launching during the two-hour window on August 29th. For example, bad weather could easily scrub a launch, or there could be unforeseen safety concerns downrange. A last minute technical issue flagged up during pre-launch checks could, equally, ruin many a scientist’s 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 a chain of unfortunate events the rocket is still earthbound following these dates, then the agency has prepared further dates running in two week on, two week off bursts stretching all the way to December the 23rd.
A huge amount 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 for the majority of the multi-week mission.
For example, the launch can only take place when the Earth and Moon are in the correct position relative to one another to initiate the transfer burn needed to place the capsule in the distant lunar orbit required for the mission.
Mission planners also needed to calculate a launch date — and therefore trajectory — that would see the spacecraft avoid falling within the Moon or Earth’s shadow for more than 90 minutes at a time. This is vital, as the Orion spacecraft’s solar panels need to be bathed in sunlight in order to generate electricity, and to provide a livable environment for a future crew.
Fancy falling
The flight also has to be planned in a way that will allow the capsule to briefly dip into Earth’s atmosphere upon return in order to slow its velocity before rising back up into space, like a stone skipping across the surface of a lake.
This piece of fancy falling cuts down on the heat buildup of atmospheric re-entry, and reduces the g-forces that would be experienced by Orion’s crew. It also allows NASA to more accurately predict where the capsule will come to splash down off the coast of San Diego.
NASA accounted for all of these criteria when selecting 8:33 a.m. EDT on the August 29th as the start of the first launch window.
Whilst it has yet to be announced, NASA is sure to stream the historic launch and subsequent coverage of the Artemis mission live on its streaming channel NASA TV. In the meantime feel free to enjoy live views of Earth as 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.