SpaceX opens new era for spaceflight with successful core stage reuse

by Chris Gebhardt

For SpaceX and its founder Elon Musk, it was a day 15 years in the making.  The accomplishment Thursday evening of launching a flight-proven Falcon 9 core stage and landing it yet again on the ASDS barge, Of Course I Still Love You, is a stunning and beautiful feat of engineering that opens the door on a new era of spaceflight, one Elon Musk states will make Humanity a spacefaring civilization.

Landing and Reusing rockets – They said it couldn’t be done… or done economically:

For decades, many stated that the long pole item to cost-effective access to space was finding a way to reduce the overall cost of the rockets needed to get us there.

The answer, in many ways, was simple: find a way to reuse the rockets – like airplanes.  Reuse, therefore, would equal a reduction in launch cost.

Importantly, work on this idea is not new to the 21st century; it was a key element in the design of the Space Shuttle in the 1970s, a design that saw three of the four major elements of the shuttle launch system designed for refurbishment and reuse – with the Orbiter, Space Shuttle Main Engines, and Solid Rocket Boosters being reused and only the External Tank being discarded after each flight.

While the overall cost reduction and rapid reuse element of the Shuttle never fully materialized (something that is well documented), the overall system of the Shuttle proved in the 1980s that rocket reusability was possible… if not rapid.

Enter SpaceX.

From the outset, SpaceX designed the Falcon 9 with reusability in mind, taking a staged approach to the Falcon 9’s overall evolution to first learn the quirks of the rocket itself in flight while simultaneously developing and testing the landing systems needed to recover the first stage.

This landing of a rocket stage through propulsive means was deemed by many in the industry to be impossible – or at least so difficult and destructive to the rocket that it would negate the cost reduction of reuse via the refurbishment needed.

What seemed even more science fiction-y than just landing a core stage by rocket propulsion down range from the launch site was SpaceX’s desire to also autonomously fly rocket stages back to the launch site and land them there when propellant margins allowed.

But regardless of what others said, SpaceX pressed forward, testing the landing technology with soft, water landings without a barge before graduating to successive attempts to land on the ASDS barge.

While those initial barge landing attempts in 2015 were not successful, success in this regard defined as the booster landing upright on the barge and remaining that way after engine shutdown, those early barge landing attempts remarkably managed to find the barge with amazing accuracy each time.

With the recovery from the CRS-7 launch mishap, SpaceX sought to make history not only with a record-breaking quick return to flight but also by attempting to bring that mission’s first stage to a successful land landing when an ocean landing on the barge had yet to be successful.

On 21 December 2015, SpaceX proved that landing a rocket vertically under propulsive power was not just theoretically possible but indeed practical when the Falcon 9 core stage, in what looked like an effortless touchdown at Landing Zone 1 (LZ-1), landed upright at the Cape Canaveral Air Force Station after lofting the ORBCOMM 2 mission to orbit.

Just over three months later, on a mission that could have made it back for a landing at LZ-1, SpaceX opted instead to send the core stage launching the CRS-8 mission to the International Space Station to the ASDS barge in the Atlantic instead.

The choice paid off as the Falcon 9 – core #1021 – landed near dead center on Of Course I Still Love You to a live web and television audience.

After that, core after core began hitting their marks on the ASDS and at LZ-1.

Underlying a seeming look of ease, though, was an incredible engineering and technical accomplishment repeated time after time – each landing event honing the process from lessons learned via flight telemetry.

Attention then quickly turned to which core would be the first one to refly, which customer would be the first to opt for this new offering from SpaceX, and when the first reflight would occur.

Originally, core #1021 from CRS-8 was intended to be a test article to give SpaceX valuable information on how cores perform in subsequent full-scale, full-duration hot fire tests at McGregor, Texas.

When the JCSAT-14 core made a remarkable hot entry landing, something SpaceX did not think it would actually be able to do, the plan changed to use the battle-hardened, operated-at-its-maximum-possible-limit JCSAT-14 core as the test article.

With that core put through its paces, SpaceX announced late last summer that the SES corporation from Luxembourg would be the first customer, with their SES-10 mission, to launch on a flight-proven Falcon 9 core.

Later, it was confirmed that core #1021 would be the core handed the honor of the first Falcon 9 flight proven reflight.

It succeeded beyond many people’s wildest dreams Thursday with not only a flawless launch per the initial data returns, but also a spectacular, dead center landing on Of Course I Still Love You.

Speaking at a post-launch press conference for media assembled at the Kennedy Space Center and via phone, Elon Musk stated his elation at the accomplishment, remarking that he was “speechless when it happened.  It’s a great day.”

In terms of what now happens to historic core #1021, Elon Musk stated that after a look to see how it held up, SpaceX plans to offer the core to the Cape for some type of permanent display.

“We think this one has some historic value.  So we’re seeing if perhaps the Cape might like to have it as something to remember the moment.  

“So we’re going to present it as a gift to the Cape.”

Martin Halliwell, CTO of SES, also stated prior to the launch that if the booster landed on Of Course I Still Love You, that Gwynne Shotwell, President and COO of SpaceX, had promised him bits of the rocket for the SES boardroom.

Going forward – short-term reusability continues and improves:

The tremendous importance of the successful reflight of core #1021 cannot be understated for what it now means for the launch market.

While it’s true that one reuse of a flight proven booster does not technically prove the durability of the system, it nonetheless proves that it is possible – and SpaceX has a way of taking the possible and making it a stunning reality.

In lead up to Thursday’s launch, many latched on to the idea that this flight was in some way more dangerous or risky than previous flights of the Falcon 9.  

Martin Halliwell of SES denied those assertions, stating that they were based on emotion and not on the technical and scientific aspect of the booster.

At a pre-launch news conference, Mr. Halliwell related that not only was SES certain from a technical standpoint that the booster was “just as good if not better” than a brand new Falcon 9 core, but that the insurers for the SES-10 mission gave them a rate that was nearly the same, with just a 100th of a percent difference in the price from an insurance policy on a new Falcon 9 core.

Speaking after the successful launch, Mr. Halliwell noted that “of the three missions we’ve had with SpaceX, this is absolutely the most calm, no problems whatsoever, absolute smooth mission.  It really couldn’t have gone better.

“We are hugely, hugely excited by this and to be a part of this.”

Mr. Halliwell also noted that while some gave SES flak for this mission, “you have to decouple the emotion from the engineering.

“The engineering team that Elon has working for him is really second to none.  And the proof is in the pudding.  Here we are.  We did it.”

So now the questions are: What now?  When will the next reflight of the Falcon 9 occur?  How many reflights will occur this year?  Then next year?

The answer is that reflight efforts will continue this year, with lessons learned from each successive reflight on how to reduce the time it takes to refurbish a core to eventually achieve the goal of reflying a core within 24 hours of its return to the Cape.

Elon Musk stated that this goal of 24 hour turnaround might be possible later this year, next year at the latest.

An important note to this is that while SpaceX, from an engineering standpoint, might be able to achieve a 24 hour turnaround for a core, the Eastern Range and SpaceX’s own launch manifest might not support an actual 24-hour back-to-back reflight of a core for sometime yet – which doesn’t necessarily take away from SpaceX’s introduction of that capability before it’s practically realized.

Moreover, Mr. Musk confirmed that there are approximately six core reuses planned for the remainder of this year.

Specifically, two of those six reflights will occur on the first flight of the Falcon Heavy, which Elon stated is still on track for a late-summer launch from LC-39A after SLC-40 is back up and running.

For the Falcon Heavy debut, the two side boosters will be pre-flown cores – one of which has already been seen under shrink wrap with its new nose cone assembly in transit to the McGregor test facility in Texas.

That leaves four possible reflights for “single stick Falcon 9” users this year.

Mr. Halliwell has stated that SES’s two upcoming autumn and winter launches with SpaceX are candidates for two of those flight proven missions.

Intriguingly, that leaves two other core stage reflight missions this year for customers who have, at the time of writing, been silent about using flight-proven Falcon 9s.

Moreover, Mr. Musk stated that he anticipates the total number of flight proven missions to increase to 12 in 2018, with an eventual goal of 75% of all Falcon 9 missions using flight proven cores.

But even with yesterday’s success and the growing forest of flight proven cores in hangers and in storage at the Cape, the goal to refine the Falcon 9 core stages so that all elements of them are durable and available for multi-reuse continues.

As stated by Mr. Musk, the goal is to build Falcon 9 cores so that they are capable of being reused 10 times in a manner that sees them land (on the barge or at the Cape/Vandenberg) in a condition where they are completely ready to just be refueled and launched again.

After those first 10 rapid reuse flights, refurbishment efforts will then allow each core to launch up to 100 times.

And this is the truly critical part to reducing the cost for access to space.

As Mr. Musk stated in the post-launch press conference, “The most expensive part of the whole mission is the boost stage.  It represents up to 70% of the cost of the flight.  So being able to refly a rocket booster, where ultimately the only thing changing between flight is the propellant, carries a cost reduction potential of over a factor of 100.

“In fact, the propellant costs for a flight is only 0.3% of the cost of a rocket.  So even when you factor in maintenance and capitalization of the cost of the rocket, the potential is there – just as it is with air flight or road travel – for over a 100 fold reduction in the cost of access to space.

“If we can achieve that, and if others can all do the same, it means that humanity can become a spacefaring civilization and be out there among the stars.  

“This is what we want for the future.”

The first step toward that goal is the coming introduction of the Block 5 variant of the Falcon 9 rocket which is set to enter service later this year.

Notably, the Block 5 – or as Elon Musk said last night could better be described as version 2.5 of the Falcon 9 – will introduce several key upgrades critical to NASA and human spaceflight exploration.

Toward aiding reusability, Mr. Musk noted that the Falcon 9 Block 5 (F9 v. 2.5) will operate its nine Merlin 1D engines at their full thrust capability, which is between 7 and 10% greater thrust for each engine than what is currently seen and will bring the total thrust at liftoff from the current 1.53 million lbf to 1.9 million lbf.

The Block 5/Version 2.5 Falcon 9 will also introduce new forged titanium grid fins – all of which will help reusability by “a couple of factors”.

Specific to the grid fins, Mr. Musk noted last night that their current design involves coating the aluminum grid fins with an ablative thermal protection system because the grid fins experience temperatures right at their maximum survivability limits during reentry and landing ops.

In fact, some grid fins have actually caught fire during the entry and landing sequence based on their current design – something Mr. Musk noted is not great for reusability efforts.

The new grid fin design will see a change in their composition away from aluminum and toward a forged titanium design that will eliminate their current design flaw and introduce greater controllability to the rocket that will increase the payload to orbit capability by allowing Falcon 9 to fly at a higher angle of attack.

The long-term plan – humanity can now become a spacefaring civilization:

While there’s no denying that the historic nature of Thursday’s successful flight-proven Falcon 9 mission will have a tremendous impact on the launch market and the launch economy, SpaceX’s goals for reusability are not just short-term but also long-term as the company looks to continue development of its Interplanetary Transport System and BFR – which Elon Musk jokingly stated last night stands for Big Falcon Rocket.

While details of the overall ITS design have been refined and are expected to be released to the public in the coming months, Mr. Musk noted that the system is being designed for reuse up to 1,000 times – something that will significantly further reduce the cost of access to space and make Mars missions as well as the Mars colonization effort not just affordable but a viable reality.

But there is a long way to go in the development of the ITS and the realization of a self-sustaining city on Mars.

Nevertheless, that crucial first step in lowering the cost of access to space has occurred.

History has been made.  The Falcon 9 is reusable.  Now the really hard work begins.

(Images: SpaceX and L2 artist Nathan Koga – The full gallery of Nathan’s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*))

Related Articles