It’s not clear why SpaceX halted the launch, though last-minute scrubs are not uncommon even during routine rocket launches. Computers or flight controllers may have caught an abnormal reading about the rocket’s health and stopped the engines from igniting. SpaceX did not disclose the reason for the delay, though the company still has the ability to conduct the test launch on Wednesday or Thursday.
SpaceX has not revealed what day or time the company is now aiming to conduct the test flight.
Previous test flights of Starship prototypes have traveled less than about 500 feet in the air and made use of only one engine. The vehicle that will be used on SpaceX’s next Starship test flight, called SN8, will be the first to have three engines installed. And it will be by far the highest and riskiest Starship test flight yet.
Musk has attempted to dampen expectations, saying in one tweet that he predicted the SN8 vehicle has a one-in-three chance of landing safely back on Earth.
The 40,000-foot test launch, however, is still expected to give the Starship plenty of room to conduct a “landing flip maneuver,” which will allow engineers to test the vehicle’s ability to reorient itself for landing as it would during the final leg of an orbital flight.
It’s not clear why the company decided to lower the altitude of this test flight, though 40,000 and 60,000 feet are still well below the 62-mile mark, which is widely considered to mark the edge of outer space.
The SN8 rocket wouldn’t be able to reach Earth’s orbit on its own anyway. The final Starship design will need six rocket engines, and even then the vehicle will require a separate, hulking rocket booster, dubbed the Super Heavy, to blast the spacecraft into orbit because that trip will require it to travel at speeds topping 17,000 miles per hour. It’s not yet clear if the company has started development or testing of the Super Heavy booster.
For a journey to Mars, Starship will also eventually need to reach “escape velocity” — about 25,000 miles per hour — which is the speed required to rip a spacecraft away from Earth’s gravitational pull, allowing it to travel into more distant regions of our solar system.
Musk founded SpaceX around his interplanetary travel ambitions, claiming he wanted to develop the technology to allow humans to settle the Red Planet.