Falcon 9 Block 5 will be "almost 10%" more powerful than the previous version.
A key feature of any rocket is its force of launch, or thrust — especially for the biggest section of a rocket, called the first stage or booster.
SpaceX's first Falcon 9 rocket stood 180 feet tall, and the nine engines of its booster could produce a thrust of nearly 5,000 kilonewtons — roughly equivalent to 2.75 adult blue whales falling upward. About a decade and several upgrades later, a "full thrust" Block 4 version of Falcon 9 emerged from SpaceX hangars. That rocket stands 230 feet tall and boasts about 7,600 kilonewtons of booster thrust.
Yet Block 5 will best that force significantly with its reconfigured Merlin 1D rocket engines.
"The most important part of Block 5 will be operating the engines at their full thrust capability, which is about 7 or 8% — almost 10% — more than what they currently run at," Musk said after a Falcon 9 launch in March 2017.
Heavier payloads can be sent into space with greater booster landing success.
That increase in thrust may help improve an important metric: Payload mass.
The first Falcon 9 could send 23,000 lbs. into low-Earth orbit (roughly 250 miles above the planet). The new version may be capable of launching more than 50,000 lbs. — double the payload — if the booster uses up all its fuel and doesn't save any to rocket itself to a landing.
But landing the booster is key to Musk's goal of drastically lowering the cost of access to space: each booster makes up about 70% of a Falcon 9's total cost.
Block 5's greater thrust, among other improvements, will help the booster get similar payloads into space while reserving more fuel for controlled landings, thus improving the rate of success.
Each booster will re-launch 10-100 times instead of twice.
Until now, SpaceX has not launched a used Falcon 9 booster more than twice. The reason: the 16-story boosters careen back to Earth from the edge of space at speeds of thousands of miles per hour, which heats and wears down their parts. The booster has to be thoroughly inspected, and parts often need to get refurbished or replaced because of damage.
To make the boosters hold up better, Block 5 will use thermal-protection coating instead of paint. Its engineers also added shielding to the tail-end of the rocket to better protect the heavy, expensive engines. And the booster's grid fins, which guide it to a landing like a skydiver's arms and legs, are made of titanium (which doesn't melt during reentry) instead of aluminum (which gets damaged).
Musk said in March 2017 that each Block 5 booster will fly a minimum of 10 times without replacing major components, though possibly more than that with some refurbishment
"In other words, the only thing you change is you reload the propellant," he said. "With moderate refurbishment that doesn't have a significant effect on the cost, it can be reflown at least 100 times."
Readying a used Falcon 9 rocket booster for launch may take weeks instead of months.
After a Falcon 9 booster lands, it takes time to ready it for a return to the launch pad — often several months. But Block 5, Musk has said, is "designed for easy reuse" that takes just weeks of turnaround time.
To make this possible, SpaceX engineers bolted on the key structure that holds the engines, called the octaweb, instead of welding in in place; this allows for quicker inspections and refurbishing work. And the ever-important landing legs will retract, so they don't have to be removed during transportation back to a hangar.
Launch costs could fall by $20 million or more.
Reusing boosters more, speeding up their inspection and refurbishment, and reducing the overall work required to reuse them translates to a lot of savings for SpaceX and its customers.
Right now the company charges about $62 million per Falcon 9 mission. The booster makes up about 70% of this cost, which means each reuse could save tens of millions of dollars. SpaceX also plans to save its $6 million rocket fairings, or nosecones, by parachuting them back to Earth.
Musk has also teased a "party balloon" solution to save the second-stage rocket, which also costs many millions of dollars (though it's not certain that this development will be ready for Block 5).
Each of these tricks could help SpaceX dramatically reduce its cost and pocket more cash. Some of those savings may be passed onto customers who are willing to fly on used boosters, though SpaceX hasn't released details about how much of a discount it might get or offer.
NASA and the Department of Defense will be more keen to launch with SpaceX.
Most of the changes that are part of Block 5, though, are designed to meet NASA's demands before SpaceX launches its astronauts into orbit.
"There are probably 100 or so changes on that vehicle," Shotwell said during a February 2017 press conference.
Some of those changes including improving pumps to withstand cracking, and redesigning a helium tank that led to a September 2016 explosion during a launchpad test. (No one was injured, since the rocket was carrying a satellite, not people.) Other tweaks were aimed at making the rocket more powerful to deliver national security missions into space.
NASA requires seven successful launches of Falcon 9 Block 5 before the space agency will allow astronauts to ride a Crew Dragon capsule on top of the rocket to the International Space Station — something SpaceX wants to do before the end of the year.
If the weather cooperates, Bangabandhu-1 — and the first-ever Falcon 9 Block 5 rocket — should lift off at around 4:12 p.m. EDT on May 10 from Cape Canaveral, Fla.