The brand new launch system announced by NASA last week has received wide mainstream media coverage – and why wouldn’t it? It is a plan for a giant rocket, after all.
The proposed Space Launch System (SLS) will provide a new way to service the International Space Station.
But let’s be clear – the SLS has one major aim, and that’s to return the US Space Agency to its core purpose: exploration.
How the rocket sizes up
After years of wrangling between the Obama Administration and US Congress, NASA was finally able to announce its proposed new rocket late last week.
First thing of note? It’s big.
The initial configuration of the SLS will be almost 100 metres tall (equivalent to a 40-storey building), and will be able to lift 70 metric tonnes to low-earth orbit.
It will use a combination of five liquid hydrogen/liquid oxygen (LH2/LOX) rockets and two strap-on solid rocket boosters to take off from the ground.
A further LH2/LOX engine will be used in the upper stages to send astronauts on interplanetary missions.
Mission to Mars
When discussing the SLS, it’s important to be clear about what it’s meant to do – and what it’s not.
It’s not designed (as some commentary has suggested) simply as a supply craft for the International Space Station. Rather, there’s a real hope the ISS can soon be handed over to commercial companies such as SpaceX.
The SLS is designed specifically, and solely, to take astronauts away from Earth to explore the solar system.
Trips by astronauts to asteroids, and then to Mars are planned. A very interesting first step being discussed is to send astronauts to Deimos, the outer moon of Mars.
Deimos is a much easier place to visit than Mars itself, as it does not require an advanced aero-capture manoeuvre for landing.
It is also high in the Mars gravity well, which means it requires smaller rockets. This is simliar to Earth’s relationship with the Moon, which sits high in our own gravity well (see below).
Making do
An interesting, but somewhat contentious, aspect of the SLS is that it makes significant use of rocket engines and supply chains left over from the Space Shuttle.
This was almost a requirement as far as Congress was concerned (members of Congress get very nervous when high technology jobs are lost in their districts), but it does have some technical merit.
For example, the Space Shuttle main engine, designed by the California-based company Rocketdyne is one of the most advanced rocket engine ever developed.
It would be a shame not to take advantage of this.
Reports of the huge job losses at NASA have been rife, following the Shuttle’s last flight. Understandably, there’s a desire not to lose the very talented Shuttle-based workforce, as happened after the Apollo Moon Program.
Will we ever see the SLS?
There is generalised support from Congress and the Obama administration for this new project. But the real question space professionals and members of the general public have to ask is whether NASA will be able to stay the course.
A few years ago under a very talented leader, Dr Mike Griffin, NASA started the Constellation Program to do the same job planned for the SLS.
Constellation was cancelled following the change from the Bush to Obama administrations, and was considered too expensive.
The same concern could be aired about the SLS. Initial estimates put the price of the rocket at US$35 billion, but that figure could easily double by the projected time of completion in 2017.
President Kennedy said in the early 1960s, “We have a long way to go in the space race. But this is the new ocean, and I believe the United States must sail on it and be in a position second to none.”
Let’s hope the SLS can stay afloat on the stormy sea of US politics, and will have the chance to take us further than we’ve gone before.