At first look, NASA’s Space Launch System (SLS) looks like the perfect rocket: heavy lifting launch vehicle that promises to be more versatile, powerful, and durable than anything that has preceded it. But there are major threats hanging over the rocket stacking the odds against it ever leaving the ground.
By design, SLS is pretty incredible. It’s central piece is a liquid fuelled core stage modelled off the space shuttle’s external tank. The core stage is flanked by two boosters that will enable early Block 1 and Block 1A versions of the rocket to lift 70 metric tons into Earth orbit. A small “kick” stage will give payloads on these smaller rockets the extra push for distant targets like the Moon. The later “evolved” SLS will feature a second stage that will facilitate lifting 130 metric tons into orbit. All three versions will be adaptable for manned spacecraft or cargo depending on the mission’s needs. As a point of reference, the evolved SLS will be as powerful as the Saturn V and less than 50 feet taller.
For all its flexibility, SLS seems like it was built with strange design choices in mind. The core stage won’t be recovered or reused after launch. The Block 1 version will use four reusable RS25-D engines leftover from the shuttle program, but when NASA’s stock of these old engines runs out it will switch to the larger and more powerful RS25-E engines – the E stands for expendable. The Block 1 boosters will also be modelled off shuttle technology, burning through solid fuel and recovered from the ocean for refurbishment after launch. The slightly larger Block 1A will introduce new boosters, possibly liquid fuelled depending on who builds them, that will not be recovered and reused. Block 2’s upper stage will add another expendable stage to the evolved rocket.
So after its first few Block 1 launches, NASA will have a single-use rocket on its hands. This was a major problem towards the end of the Apollo program. Saturn Vs were expensive to produce and launch, especially since each could only go up once. Post Apollo plans that relied on the Saturn V’s lift capacity were scrapped and reusability as a cost-saving measure was a main factor in the shuttle’s design.
Like the Saturn V, the cost associated with SLS launches could prove prohibitive. Early estimates suggest that each launch could cost between $8,500 and $10,000 to deliver just one pound with SLS. For the Block 1 and 1A to launch the maximum 70 ton payload, that’s $1.3 billion per launch; the Block 2 will cost about $2.45 billion per 130 ton payload. As a reference point, each shuttle launch cost roughly $1.5 billion, and each Saturn V around $1.17 billion (adjusted to 2012 dollars). If these SLS launch estimates prove true, it’s hard to see how the space agency will sustain the rocket. Critics are slamming SLS for its high cost. In addition to launch costs, SLS is expected to cost $10 billion in development leading up to the first launch.
With such high launch costs, every one has to count. But SLS doesn’t have clear goals for the new rocket. The first SLS-launched mission, scheduled for December 17, 2017, will see a Block 1 send an unmanned Orion spacecraft on a free return trajectory around the Moon. The next launch sometime in 2019 will see a crew make the same flight. After that, tentative plans call for one launch each year. Destinations include the Moon and near Earth asteroids. Once the Block 2 makes its appearance sometime in the 2030s, we will see missions sent to Mars.
2030 is a long way away, and for SLS to last that long it will need funding. Funding, in this case, from Congress. Orion and SLS are the two surviving pieces of the Constellation program started under President Bush Jr. and cancelled by President Obama. After sparing SLS, members of Congress began making demands on and setting parameters for the rocket going so far as to specify contractors. Individuals are working hard to secure contracts for companies in their home state, creating jobs and winning the support of voters. The heavy hand of self-interested lawmakers has led some critics to call SLS a job-retention program disguised as a rocket and landed SLS the unfortunate nickname of “Senate Launch System.
To make matters worse, despite its scheduled launch dates SLS still lacks support. And with another election around the corner, it’s nearly impossible to predict what will happen in the next few years. With the right space-supporting people in positions of power, it may come to fruition? But if SLS’ critics make up the majority it will be a different situation. Unfortunately, without concrete goals that the public can really understand and get excited about, it’s likely votes will go to those state representatives hoping to kill the SLS program before it gets too far.
It’s an unfortunate “wait and see” situation. The worst case scenario is to see SLS scrapped, the research from its early development and planning is applied to another program while the documents written in the electronic age become a goldmine for future space historians. The best case scenario would be for NASA to establish and commit to concrete goals for the a program that sees SLS through its development, giving us a means to explore and unravel more mysteries of our solar system.Missions » Apollo »