-Ayush Shivkumar

Rocket launches continue to pose the most significant challenge to modern-day space travel. They are cumbersome on the pockets due to the sheer magnitude of fuel they require. The heavier the rocket, the more the fuel, which causes the rocket to get even heavier, leading to even more fuel. We spend enormous money on launching rockets, between hundreds of millions to billions of dollars. There is a growing need for Non-Rocket Space launches, and we will be discussing the Skyhook, Rocket Sled Launch, and Rockoon strategies in detail here.

The Skyhook consists of a heavy station orbiting the Earth with a long, taut cable reaching the upper atmosphere. We will then mount payloads lighter than the station to the end of the cable, and they will get flung out into the desired trajectory via rotation about the system’s centre of mass.

We can then re-orient the skyhook using tiny propellants. The only hitch is that we require a suborbital launch vehicle to reach the cable’s end in the upper atmosphere. This process would still require immense energy, even if combined with a reusable rocket.

Of the more prevalent alternatives is the rocket sled launch, the ground-based launch assist, or simply the rocket catapult, which consists of an eastward-pointing magnetic levitation rail (maglev rail) that trails up a mountain. The spacecraft is loaded at the top, and an external force is applied to provide the initial acceleration.

The spacecraft then races down the elevation, which vastly reduces the fuel required to be carried. This allows for a larger payload with minimised costs to reach sub-orbital, orbital, or inter-planetary destinations. Tracks at Holloman Air Force Base have tested, as of 2011, small rocket sleds moving at hypersonic speeds of up to 6453 mph.

Rockoon, stemming from ‘Rocket’ + ‘Balloon’, is a launch strategy in which a gas balloon first carries a rocket to a certain level, after which ignition takes place. This allows the rocket to reach a certain altitude before consuming fuel, thus reducing the overall costs. The major disadvantage is that we can’t control the balloon, and external factors like winds may change our desired trajectory.

Engineers are constantly developing new ideas for unconventional space launch strategies, such as the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) being designed by the private spaceline; Ad Astra Rocket Company, which could theoretically take a measly 39 days to reach Mars.

There are many such attempts to design functional and efficient modes of reaching space other than traditional rockets, but for the time being, the good old rocket launch is the only way upwards. References:

https://en.wikipedia.org/wiki/Non-rocket_spacelaunch

https://en.wikipedia.org/wiki/Rocket_sled_launch