It takes a lot more than knowing Newton’s III law to put a piece of metal into orbit. From finding the right combination of propellant for proper combustion to choosing the materials to survive the million-pound thrust, the engineering design challenges facing a rocket engineer are, not so surprisingly, huge.
The Saturn V rocket carried 2 million litres of fuel (kerosene + liquid oxygen) for combustion. It takes $10,000 (7 lakhs INR) to put a pound of weight into earth’s orbit. Decreasing the payload to the bare minimum is one of the challenges the engineers face. A typical cargo to International Space Station weighs around 50,000 pounds(23,000 kg) and the cost of the mission ranges from $500 million to $1 billion. So, an ounce of fruit, on-board might cost around $1,000!
Lower end payloads like that of Chandrayaan weighed around 1,380 kg at launch and 675 kg at lunar orbit. The mission costed around $80 million making it least expensive lunar missions in the world compared to Japan’s Selene ($480 million) and China’s Chang’e ($187 million).
How TeamIndus Planned To Take A Shot At Moon
Landing
Team Indus aims to land on the moon next year, in the vast lava plains of Mare Imbrium. And, to make the most of its mission, the team plans to land at dawn, to maximise surface operations. The position of Sun also plays a key role in carrying out the mission objectives as the rover is solar powered. To evade additional time constraints and to meet predetermined post-dawn landing arrangements, the lunar orbit of the spacecraft needs to be inclined which is done using the spacecraft’s propulsion system.
Propulsion
The main engine on the spacecraft is a liquid rocket engine utilising Hydrazine (N2H4) as the fuel and an oxidizer majorly composed of Nitrogen Tetroxide (N2O4). The resultant system has a thrust capability of 440 N for major manoeuvres.
The fixed thrust propulsion system, employed by TeamIndus is the first of its kind ever used for a lunar mission.
To feed the propellant even at zero gravity, a surface tension based Propellant Management Device (PMD) is used, which rests inside each of the tanks holding onto a small amount of propellant so as to supply the fuel even at zero-g. Once the engine fires, the resultant forces on spacecraft will drag the fuel in the direction of the feed line, allowing for a continuous propellant supply.
And, to tackle the challenge of inconsistent thrust delivery, a Heater Propulsion Card is employed to automatically control the valves in accordance with the pressure drops in the feed system.
Orbital Mechanics
It will take 5 days to reach the moon by traversing along the Lunar Transfer Trajectory(LTT) to optimize the energy spent.
The engine burn will have to be timed perfectly to be captured by moon’s gravity. So, the main engine will burn longer to decrease the velocity such that, the vehicle velocity is less than that of moon’s escape velocity(2.38 km/s).
The above figure illustrates how timing the engine burn at the intersection of farthest point from the earth and the nearest point of the moon, gets the spacecraft into lunar orbit. Once in orbit(S1), the spacecraft needs to be stabilised to start the lunar descent.
The descent needs to be timed as well, which otherwise would need the spacecraft to spend more fuel or will crash land. The spacecraft is then manoeuvred for subsequent S2, S3 and S4 orbits; changing its course from elliptical to circular.
A circular orbit allows the engine burn to be performed anywhere in S3 and choose S4 accordingly; requiring least amount of energy.
Alignment
It is extremely crucial for the spacecraft to do attitude adjustment to align with the sun such that its solar panels are well illuminated. This is done with the help of Attitude Control Thrusters(ACTs).
By firing a given combination of these thrusters in a series of short pulses, the spacecraft can be made to point in any direction. This enables the spacecraft to face the Sun throughout the journey to the Moon.
Pre-Production Hassles
The right combination of propellant could be figured out; the drag and thrust equations might have been balanced diligently but, if there is one factor that decides the fate of this ambitious dream, then that is ‘money.’
From manufacturing the components and importing the technologies to paying the crew, the motivation and success can only be fueled with the right amount of funds.
According to a leading science magazine, Americans paid $26 from their pockets to fund the lunar landings in the sixties. Modern day equivalent of this would be $200 per person which would have added $50 billion more to the current NASA budget of $20 billion. But, unfortunately, the tax cuts stop at a scant $54 per person per year.
We are talking about NASA here; the agency which put the man on the moon and had single-handedly realised a 10,000-year-old dream within a few decades. If NASA, with successes like Apollo, gets questioned to be funded, one can imagine the position of a private space agency like TeamIndus in a developing country like India.
Since winning the NASA’s Lunar X prize back in 2010, TeamIndus has raised $ 20 million in Series-A funding whereas, launching a payload can cost another $ 35 million. As discussed above, space missions are not cheap and given the success rate, raising funds for a space startup is different from any other startup.
Since investors are more trust based and risk-averse, TeamIndus is having a hard time convincing the investors and was on the verge of shutting down; twice in the last 7 years.
There are only a handful of private companies around the world who have embarked on this laborious lunar journey. Of which, many are either in the development phase or have cancelled their plans altogether. TeamIndus’ Japanese counterparts who were one of the Lunar X prize finalists, are currently in the testing phase and plan to land on the moon by early 2020.
“I have dreamed of space exploration all my life,” said Aditya Kodandapani, systems designer of TeamIndus, speaking to a leading online daily.
The longevity of their mission depends on how much funding they get in the coming years. To realise their dream, the team has to raise around $400 million over the next decade. The leadership at this India’s first private space company believes that money won’t be a problem once they establish trust by successfully landing their planned rover on the moon.
In early November, TeamIndus joined the consortium led by OrbitBeyond, a new space transportation company, as a part of the NASA lunar scheme to engineer the lunar landings.
“Commercial Lunar Payload Services [CLSP] contracts are indefinite delivery, indefinite quantity contracts with a combined maximum contract value of $ 2.6 billion during the next 10 years,” said NASA while announcing the bidders.
Why Bother Looking At The Skies
NASA scientists have pioneered more than 6,000 technologies over the last six decades that are now routinely used in day-to-day living. Here are few applications, which the flat-earthers and other naysayers conveniently use:
- CAT scanner: this cancer-detecting technology was first used to find imperfections in space components.
- Satellite television: technology used to fix errors in spacecraft signals helps reduce scrambled pictures and sound in satellite television signals.
- Scratch-resistant lenses: astronaut helmet visor coating makes our spectacles ten times more scratch resistant.
ISRO’s Chandrayaan-I was successful in detecting water on the moon. One might argue about the significance of locating water 384,400 km away but there is more to it. The technology used in Chandrayaan was later used for mineral tracing on earth.
Missions such as this could further be leveraged for societal development such as Tele-education, Telemedicine, Village Resource Centre (VRC), Disaster Management System (DMS) Programmes and many more.
