Space Launches: Why Reusability Matters

The Artemis I mission of the National Aeronautics and Space Administration (NASA) was recently completed successfully. Things came a full circle on 30 December, with the Orion spacecraft returning to the Kennedy Space Center.

The Artemis missions are NASA’s attempts to send astronauts back to the Moon after a lapse of five decades. The recently concluded first mission carried a dummy crew member in its Orion crew capsule, which rode on top of a launcher called the Space Launch System, or SLS.

The mission validated all the parameters before any actual humans are launched towards the Moon in a couple of years' time. Everything went well with the maiden mission and NASA is on track for astronauts to touch down on the lunar surface around 2025.

In spite of the success of the mission, most things associated with the Artemis I mission are destroyed.

The SLS itself is gone — burnt up in space. What came back and splashed into the Pacific Ocean was just the Orion crew module, which is a bell-shaped container, very small in comparison to the launch system.

The module itself is a museum piece now; it cannot be launched into space again.

As we dissect the launch system and gauge the amount of waste associated with each space mission, it all leads to the conclusion that missions are very expensive and unsustainable from an environmental point of view. It is simply not scalable to support routine traffic to and from space. It is like a car getting destroyed after just one trip.

To be fair, these initial missions are only discovery missions and proofs of concept. Optimality would be injected into the designs as we head into the future. As private sector participation increases further, more emphasis will be placed on reusability and cutting down costs, leading to sustainability and repeating operations on a larger scale.

Let us take the example of the SLS and how it compares with the Saturn V rocket that was used for earlier human spacecraft missions to the Moon in the 1970s.

The picture below, courtesy NASA, shows the two rockets side by side, along with the famed Statue of Liberty in New York City.

The first stage of the SLS, represented by the orange-coloured section, houses the liquid hydrogen and liquid oxygen tanks, which fuel the four RS-25 engines at the bottom.

These are the same engines that powered the space shuttle of the yesteryear. To each side is a solid rocket booster, which provides additional thrust, similar to the space shuttle design.

The topmost spire-like structure is the launch abort system. If, for some reason, the rocket needs to be aborted after launch, the spire along with the astronaut-carrying capsule are separated out and taken to a safe landing.

The bell-shaped tiny structure below the spire is the crew capsule. Named Orion, it is designed to carry human beings to the Moon. For Artemis I, it carried a dummy human being.

Just below the crew capsule is the cylindrical service module, which carries the solar arrays and communication equipment. This unit has been built by Airbus and is Europe’s contribution to the mission.

The crew capsule and the service module fly together as one unit to the Moon and come back to the Earth. The service module is jettisoned just before entering the Earth’s atmosphere.

Wedged between the first stage and the service module top stages is the Interim Cryogenic Propulsion Stage (ICPS). It is likely to be replaced by other designs in future Artemis missions. Hence the word "interim."

After launch, the first stage falls off after pushing the rocket enough towards space. The ICPS pushes for some more time and then falls off. What is left is the crew capsule and service module, which travel together for most of the life of the mission.

The reusability of the first stage of rockets was pioneered by a private company, SpaceX, which was started by Elon Musk.

The first stage of the SpaceX’s Falcon 9 rocket separates and safely comes back to Earth and lands on the ground or on a ship in the ocean. After a few failures, several such refurbished first stages have been reused, thereby reducing the cost of launch.

SpaceX’s next venture is the Starship, which is the equivalent of NASA’s SLS. This rocket will be flight-tested early 2023. It is a two-stage rocket and both of them are designed to come back safely to Earth and land. It is intended to be a fully reusable rocket and will reduce the launch costs even further. Other companies like Jeff Bezos’ Blue Origin have followed suit with reusability.

India has its own launch vehicles, the polar and geosynchronous satellite launch vehicles (PSLV and GSLV), which have seen a lot of launches and successful deployment of payloads. But neither of them is reusable.

India’s space efforts have largely been dominated by the Indian Space Research Organisation (ISRO), the Indian government equivalent of the United States (US) government's NASA. That is changing now. Several private sector companies are now supplying components to ISRO.

More recently, a private company, Skyroot Aerospace, launched its first rocket, Vikram-S. Reusability is on the agenda for Skyroot as well as ISRO.

India’s launch costs are lower, largely due to cheap, skilled engineers. But India cannot bank on that factor alone for long. As the Indian economy grows, the wages will start to rise and the wage differential will begin to narrow down. Reusability is the only factor that will ensure competitiveness and environmental sustainability.

Beyond reusability, it will be the efficiency of the engines and the choice of sustainable fuels that will matter a lot. Some progress is being made on this front too. SpaceX’s Raptor engines are more efficient and powerful than NASA’s older RS-25 engines.

The greening of space is not just a philosophical nicety. It is an economic imperative too.