The Space Launch System has been the subject of heated debates, but what’s the alternative for going to the Moon, Mars, and beyond? (credit: NASA) |
by Ajay Kothari
Monday, March 15, 2021
Several days after the editorial board of Bloomberg recommended that the Biden Administration cancel the Space Launch System (SLS), Loren Thompson published a rebuttal in Forbes. But I respectfully, if strongly, disagree with Thompson. The future of the SLS is of immense importance to NASA and the country, and thus to the taxpayers, and hence we need to attempt as soon as possible to set the record straight.
Thompson says, “The editorial board at Bloomberg News launched a nonsensical attack on NASA’s human spaceflight program last week. It was full of dubious assertions about alternatives to the Space Launch System.” And yet it is his attack that seems motivated for self-centered reasons, and is full of questionable assertions.
Yes, as the Bloomberg editorial said, SLS needs to be scrapped. But not only that, we need to change the paradigm of how we do space travel. Building a bigger and bigger rocket every time to fit a bigger mission, the crux of Thompson’s argument, is asinine and unnecessary. With the advent of many reusable rockets by SpaceX, Blue Origin, and hopefully soon Rocket Lab, we are in a different territory. Let us, as a country, take advantage of it or someone else will do it first.
The problem, simply put, is that larger payloads and farther destinations require more propellant, which in turn requires bigger rockets to boost them. So, our plans also get limited in what we have available that day in terms of rockets.
| Building a bigger and bigger rocket every time to fit a bigger mission, the crux of Thompson’s argument, is asinine and unnecessary. |
What if we do not have to be limited this way? This is possible by docking multiple upper stages in low Earth orbit (LEO), one carrying the payload and all others carrying that much extra fuel by the same reusable booster(s). No refueling required for now, as the Forbes article posited as alarm—perhaps that can come later. In nerd-speak, what this does is to increase the propellant fraction until it is equal to what is needed to do the job. This gives us an ability to have theoretically infinite solutions for space travel, basically tailored to fit the need. Want to go to Moon? Two flights of Falcon Heavy. Want to go to Mars instead? Four flights of Falcon Heavy. A little extra boost needed? Rocket Lab’s new Neutron can fill the gap. A bigger gap? New Glenn of Blue Origin can help out.
It builds a railroad to space with thousands of solutions at our finger tips. Let us build this railroad instead of the one-off solutions like SLS. This is not rocket science!
This was not possible earlier. But now the reusable rockets have proven considerably less expensive to fly, and the upper stages have less weight. It is almost a sure bet that many other countries, especially China, will follow this method and leave us in dust if we do not adopt this. China is already developing reusable rockets. If we stay with the current status quo, we will lose this race to China, who will have thousands of possible paths to NASA’s one or two using SLS. Do we really want to be in that pickle?
This solution exists today! Docking in LEO has been done since 1966, and is being done today frequently, and often automatically, at the International Space Station. The answer is simple: save the $2 billion per year spent on SLS and put some of that into developing in-space refueling technology, lunar surface infrastructure, and water-ice extraction technologies; some can even be reallocated for climate change. It is a huge saving, and we need to take a step now with the new administration.
To supplant the above arguments with numbers, SLS cost is pegged at about $2 billion per launch and its payload capability for LEO with Block 1 is 95 tons and Block 2 cargo 130 tons. Falcon Heavy, pegged at $125 million per launch with its semi-reusable option (the two side boosters recovered and core expended) has around 54 tons capacity to LEO. Four flights of it can deposit more than 200 tons in LEO, which is twice as much as one SLS Block 1. Thus, the approximate numbers now are $2 billion vs $500 million for twice the payload—a factor of eight advantage. Why would we not do this? Mind you, this does not require refueling, just docking. And as icing on this cake, we can also use some upper stage tanks as habitats. Is this rocket science? No. Just common sense, perhaps with some innovative, out-of-the-box, bold thinking that NASA used to be known for.
Schedule. That we should “commit ourselves to achieving a goal before this decade is out of landing man on the Moon” was announced in 1961, and was fulfilled despite those clunky computers and the first-time feats for almost all of the successes. NASA taking longer for the Space Shuttle was already the beginning of different NASA from the one in ’60s, which has just proven it is in a huge bureaucratic decline now thanks mainly to the unfair political pressure being exerted by some Senators and the likes of companies that Mr. Thompson represents. There has to be a limit to stretching this string unreasonably harder. It needs to break now. Yes, SpaceX was five years behind schedule for Falcon Heavy. But SLS is already at year ten after the development was announced and has not flown yet. No, those excuses just don’t wash any more.
| This method, which is possible only with reusable booster rockets and not with SLS, not only creates the path to the Moon and Mars but also many other destinations in solar system. |
Cost. Let us just look at the actual savings to taxpayers here in the example Mr. Thompson mentions in his essay, where he compares Starship’s projected $2 million launch cost versus the $331.8 million NASA just paid for a Falcon Heavy launch. Starship’s quoted cost by SpaceX indeed is absurdly low and may not pan out. But even taking that number into account, NASA is being taken to cleaners for $329.8 million more than should have ($331.8 million – $2 million), for the sake of argument. But in case of SLS, where each launch costs approximately $2 billion each, it is a higher number by about $1.67 billion, which the taxpayers will bear the brunt of. Which is a higher burden? It is not just the ratio that matters. For taxpayers, it is the actual dollar amount.
Technology. The most impactful technology, possibly by far, that was developed by SpaceX is the sequence of the boostback maneuver, engine restarts, and landing on a droneship or returning to the launch site. This is what will save considerable sums that make unthinkable doable. It changes the paradigm that helps not just this country but humanity. To make light of this by comparing it to the “world’s largest welding tool,” as Forbes does in its assessment of new technology on SLS, is to intentionally keep blinders on.
Justification. The method outlined above, which is possible only with reusable booster rockets and not with SLS, not only creates the path to the Moon and Mars but also many other destinations in solar system. Again, the common denominator is to not use SLS or any expendable rocket solutions, which are huge money pits. If we do not think China will embrace this development, while the US again falls victim to political and big business arm-twisting, then we have another set of blinders on. It may not be just that this time around. It may also be a security threat in terms of China moving much farther ahead of us in the space arena, particularly cislunar space, if we do not take action soon.
Thompson expounds that “several companies on the SLS team including core stage contractor contribute to my think tank.” Here on the other hand, no companies—SpaceX, Blue Origin, Rocket Lab, or any other team—have contributed to this opinion piece.
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