SLS: NASA’s most powerful and controversial rocket is ready to launch

At the end of 2016, the aerospace industry held its breath as the largest and most powerful rocket ever built – NASA’s Space Launch System (SLS) – prepared to lift off from the Kennedy Space Center in Florida. A worthy successor to the Space Shuttle, the SLS is a successful collaboration of some of the world’s largest aerospace manufacturers, and a project rivalled only by the Saturn V rocket that launched the Apollo astronauts to the Moon and back in the 1960s and 70s.  

But the launch never happened. While it was originally mandated to launch before the start of 2017 by the US Congress, the SLS was delayed. This would be the start of many further delays, with at least 16 taking place following the start of the program in 2010. The rocket became one of the most ridiculed projects in NASA’s history.   

However, it now appears that, finally, there is no need to delay the launch any longer. In August 2022, NASA announced that the SLS’ first mission, Artemis 1, is planned for August 29. While the date is not set in stone, and additional delays could still occur, this is the closest we have come to the launch since the program’s inception more than two decades ago.  

But will the launch be sufficient to rid the project of its tarnished reputation? After years of delays and controversy, this seems unlikely. 

Not up to the task? 

On paper the SLS is the most powerful launch vehicle to ever exist. Its four core engines and two boosters can generate 8.8 million pounds of thrust, with later versions upping that amount to 9.2 million pounds. This is almost 300 times more than the CFM LEAP, an engine which propels the latest generation of mid-range airliners, including the Boeing 737 MAX and the Airbus A320neo.  

By this metric alone the SLS is more powerful than the Falcon Heavy (5.1 million pounds) which is the current record holder for operated vehicles. It is also slightly more powerful than the Saturn V (7.8 million pounds). However, there are scores of space enthusiasts, journalists and pundits who failed to be impressed by the raw power of the SLS.  

Despite being more powerful, the rocket is smaller than the Saturn V. It is also much more expensive. Adjusted for inflation, the cost of one launch of the Saturn V in the 1960s was around $1.5 billion, which is a far cry from the $4 billion required for just one SLS launch.  

Most importantly, at a glance, all this power appears to be for nothing. Multiple sources have suggested that the SLS can carry 95 metric tons (210,000 pounds) to low Earth orbit (LEO) and 46 metric tons (101,000 pounds) to the Moon. Surprisingly, this is less than Saturn V, which holds the current record for transporting 140 tons (310,000 pounds) to LEO.  

So, after all the years of progress, how has NASA’s program not resulted in a vehicle far superior and more efficient when it comes to transporting objects into orbit than the already 60-year-old Saturn V?  

Many critics have suggested that the problem could lie in corruption, political meddling, a lack of competition, and a host of additional issues that have beset the industry since the end of the golden age of space exploration.  

Is there some truth to these claims? If we take the cost overruns, multiple delays, and the lack of response to critics into consideration, then the companies and agencies behind the program could be perceived as being culpable.  

The differences 

There is also the simple fact that comparing the SLS, and the Saturn V is not entirely fair. They are both different systems intended for different purposes.  

From the beginning, the SLS was intended to have a host of variants. The largest of these would have surpassed the Saturn V in both size and payload capacity, with the Block 1, now scheduled to launch on August 29, serving as a proof of concept rather than a finished rocket.  

The interchangeability of the components between variants (as well as the Space Shuttle which was retired long before the SLS was finished) and the necessity to carry out different missions has had its toll on efficiency.  

The most powerful of the SLS’s variants was expected to carry approximately the same amount of payload to the LEO as the Saturn V and do that more efficiently.   

In addition, multiple experts have claimed that comparison between the SLS and the Saturn V is based on inherently flawed methodology. These experts suggest that the way the weight of the payload was calculated back in the 1960s was different as Saturn’s record-breaking 140 tons included the actual upper stage of the rocket, the inclusion of which would put SLS’s payload way above the widely publicized mark.   

However, this does not deflect from criticism regarding the costs, delays, and the troubled history of the rocket’s development.  

But this logic appears to have a huge Starship-sized hole in it.  

The competition  

Several alternatives to the SLS have been proposed over the years, and the most well-known of these, the SpaceX Starship, has been stealing the spotlight as the world’s most-awaited rocket.  

Had its launches not been delayed due to environmental reviews, Elon Musk’s new creation is likely to have been launched back in 2021. It would also surpass the SLS in size, power and, crucially, cost, reportedly requiring a mere $2 to $10 million for a launch.  

While the low cost could have been exaggerated for marketing purposes, there is no denying that the Starship will be a much cheaper system – and it will also be reusable.  

Additionally, its development was much cheaper, shorter, and less problematic than that of the SLS. The simplest way to understand this is to take a look at the timeframe. Back in 2017, the year the launch of the SLS was first envisioned, the Starship was still just a concept. The latter has been through several iterations, and a whole development cycle, while the SLS continued to experience delays.  

So, is there still a need for the SLS? NASA seems to think there is and is continuing to pour money into its development. The rocket’s maiden launch will be the first test of the agency’s conviction. 

UPDATE 08-29-2022, 16:00 (UTC +3): On August 29, approximately 40 minutes before the planned lift-off, NASA announced that the launch is being delayed due to SLS’ engine problems.


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