Falcon 9 rocket: How did SpaceX build its reusable marvel tech ?

With the launch of his company's reusable Falcon 9, Elon Musk promised more affordable space travel. However, how does this rocket function specifically?

Monday, December 6, 2021 | Chimniii Desk

Key Highlights

The rocket made history in 2012 by becoming the first privately launched vehicle to successfully complete a resupply mission to the International Space Station, and it has since added reusability to its capabilities.
The Falcon 9's first stage is reliant on the metal Octaweb structure that houses the Merlin engines.
SpaceX does not manufacture the Falcon 9, but rather assembles it in Florida.
Raptor will, however, make its debut on an upgraded version of the Falcon 9 prior to launching to Mars.

Advertisement

Falcon 1 Blue-Print

When Elon Musk's SpaceX – an acronym for Space Exploration Technologies – entered the rocket business, it promised reusability, lower launch costs, and more convenient access to space. The company has made steady progress toward fulfilling that promise over the last few years, aided in no small part by the success of its Falcon 9 rocket.

The Falcon 9 is a two-stage rocket designed to launch satellites into orbit and eventually crewed spacecraft. It stands 69.9 metres tall, weighs 549,054 kilogrammes, and generates 7,607 kilonewtons of thrust at take-off, capable of launching 22,800 kilogrammes into orbit around the Earth. Alternatively, it could send 8,300kg to Mars, although nothing has yet been launched to the Red Planet. Nevertheless, Mars is SpaceX's ultimate goal – Elon Musk has made no secret of his desire to be the first to land humans on our neighbouring planet.

Meanwhile, SpaceX has successfully launched over 40 Falcon 9 rockets into Earth orbit. The rocket made history in 2012 by becoming the first privately launched vehicle to successfully complete a resupply mission to the International Space Station, and it has since added reusability to its capabilities. This is another step toward SpaceX's goal of sending humans into orbit from American soil, a feat not seen since the Space Shuttle's final flight in 2011. However, for the time being, it is not limited to NASA missions. The launch manifest for SpaceX reveals a diverse clientele, including the US Air Force, national security missions, and commercial satellite launches. In sum, SpaceX is establishing itself as a pioneer in the new era of commercial spaceflight.

Advertisement

Relaunch of the Falcon 9 rocket

Credit: SpaceX

SpaceX signed a 20-year lease with NASA in April 2014 to use launchpad 39A, the same launchpad from which every Apollo mission (except Apollo 10) and a number of Space Shuttle missions launched. SpaceX had to customise the pad to support the Falcon 9 launch. It refurbished the deluge system, which uses water to shield the rocket from its own acoustic energy during launch. Additionally, it upgraded electronic components, electrical and plumbing lines, and the liquid oxygen storage system used to fill the rocket's tanks prior to launch.

Mating Octawebs

Mating the Octaweb of a Falcon Heavy centre core to the tank © SpaceX

The Falcon 9's first stage is reliant on the metal Octaweb structure that houses the Merlin engines. The rocket's early versions featured nine engines arranged in three rows of three. Eight engines are clustered in a circle around a central one when using the Octaweb. The unique engine configuration serves a purpose beyond aesthetics. The Octaweb shortens and lightens the Falcon 9 thrust structure, simplifying its design and assembly. Ultimately, streamlining the manufacturing process reduces launch costs.

Advertisement

Interstage

SpaceX engineers inspect one of the Falcon 9’s interstage sections prior to assembly © SpaceX

Any rocket with multiple stages requires an interstage. This section connects the first and second stages and also contains the second stage's engine, which is protected during the initial phases of flight. The interstage separates the two stages at the proper moment, allowing the second stage to fire safely. This is referred to as the'staged moment.'

While separating rocket stages can be challenging, the Falcon 9 simplifies the process. While the majority of rockets utilise a complex pyrotechnic system of explosive bolts to separate stages, SpaceX utilises an entirely pneumatic stage separation system. This system can be tested on the ground and also reduces the shock to the rocket during staging.

Merlin-powered aircraft

A Merlin engine being prepared for testing. The Falcon X carries 10 of these engines © SpaceX

The Merlin engine, which is built in-house by SpaceX, provides the thrust for the Falcon 9. The rocket's first stage features nine of these engines clustered together, while the second stage features a single Merlin modified to operate in space's vacuum. These engines are powered by a mixture of rocket-grade kerosene and liquid oxygen known as Rocket Propellant 1. The first stage engines burn for 162 seconds during a typical Falcon 9 launch, while the second stage engines burn for 397 seconds.

The Merlin engine is a monstrously powerful and efficient engine, one of the most efficient ever built. Additionally, having nine of them in the first stage adds an element of safety. On other rockets, if an engine fails during launch, the resulting loss of thrust can eliminate the payload's chances of reaching orbit successfully. However, the Falcon 9 is designed in such a way that it can launch even if two of the nine Merlin engines in the first stage fail. Healthy engines can operate for longer periods of time, picking up the slack and rescuing the mission.

Advertisement

Facility for Vertical Integration

SpaceX does not manufacture the Falcon 9, but rather assembles it in Florida. The majority of the rocket's components are manufactured elsewhere, most notably in the company's Hawthorne, California, factory. This means that components such as fuselages and engines must be transported by truck throughout the United States to various test stands before being delivered to NASA's Kennedy Space Center in Florida.

After arriving in Florida, the components are mated in SpaceX's custom-built Horizontal Integration Facility, a large hangar adjacent to launchpad 39A.

The landing of the first stage

A Falcon 9 rocket touches down on one of the two offshore landing platforms © SpaceX

The most exciting part of any Falcon 9 launch, particularly the first stage's landing on a floating barge. The Falcon 9's first stage is equipped with four small carbon fibre landing legs that are stowed against the fuselage. The first stage of the rocket begins its descent through the atmosphere after it has completed staging. The rocket is flipped upright by cold gas thrusters located near the top. The stage engine then fires briefly to slow the stage's descent. Legs deploy as the stage nears its destination. Three of the nine Merlin engines fire a final time during the final stages of the descent, which SpaceX refers to as the 'boostback burn.' The stage slows even more, hovering almost imperceptibly as it makes a soft landing. This landing sequence is completely automated, with the rocket stage responding in real time to real-time data.

Advertisement

Raptor Engine

The Raptor has not yet flown and has been successfully tested on the ground. SpaceX, on the other hand, has grandiose plans for it. This engine will power future missions to other planets, beginning with Mars. The company recently unveiled its design for an interplanetary spacecraft, which in its current configuration uses a whopping 42 Raptor engines in the launch vehicle's first stage to lift off. Raptor will, however, make its debut on an upgraded version of the Falcon 9 prior to launching to Mars.

Post-flight Falcon 9

After a successful landing, the Falcon 9's first stage is returned to the Horizontal Integration Facility for inspection, refurbishment, and reconditioning in preparation for another launch. Reusing the stage is significantly more cost effective than constructing a new one for each launch. The SES-10 mission in March 2017 marked the first time a core stage of an orbit-capable rocket was reused, and the cost was "significantly less than half" of the cost of building a brand new stage.

Elon Musk has made a comparison between single-use rockets and single-use aeroplanes. If an airline was required to scrap a Boeing 747 after each flight, flying would become prohibitively expensive for the average traveller. However, aircraft are not single-use; they are refuelled for subsequent flights. If a rocket can be refuelled in the same way as an aeroplane, the enormous cost of space travel could be reduced to a fraction of what it is now. And just think about the ramifications!

Advertisement