Update: The SpaceX rocket launch scheduled for Monday has been cancelled due to a helium leak, NASA said via Twitter this afternoon.
Space Exploration Technologies is scheduled to launch its latest Falcon 9 rocket from the Cape Canaveral Air Force Station in Florida on Monday evening, marking the private spaceflight company’s fourth flight destined for the International Space Station.
But in a notable first, the Hawthorne, Calif., company has equipped the rocket with four landing legs, enabling an early experiment in SpaceX’s long-term efforts to create reusable rockets. Achieving this aim would dramatically decrease the cost of deployments, a critical step for achieving SpaceX Chief Executive Elon Musk’s founding mission for the company: Colonizing Mars.
“The analogy we like to use is, ‘How many people would fly if you could only use a jet one time?'” SpaceX spokeswoman Emily Shanklin said in an interview.
In order to bring a large group of people to the Red Planet you need a reusable vehicle so you can amortize production costs over multiple flights, as airlines do, she said.
But to be clear, the company doesn’t have high hopes for its first attempt following Monday’s launch, which is scheduled for 4:58 pm ET.
Here’s how it’s all supposed to work:
The Falcon 9 is a two-stage rocket that will carry the Dragon spacecraft into orbit.
The first stage has nine engines on the bottom, which can generate more than 1.5 million pounds of thrust — the equivalent of five 747s lifting off at once. It burns through its fuel in about three minutes, at which point it separates and begins falling back toward Earth.
The second stage, with a single engine, then carries Dragon into low-Earth orbit, which takes another six to seven minutes. At that point, it drops away too, leaving Dragon to navigate toward and dock with the space station using its own, smaller thruster engines.
For Monday’s flight, Dragon will haul nearly 5,000 pounds of cargo, both in its pressurized capsule and in an unpressurized trunk. The second stage of the rocket is not recovered, but the timing and location of the initial launch are all calibrated to enable the first stage to splash down into the Atlantic Ocean.
For this mission, SpaceX is aiming to relight the engines of the first stage twice: Once with three engines to slow it down as it re-enters the atmosphere and once again with a single engine to reduce velocity as it approaches the water. About 10 seconds before it hits the ocean, they hope to successfully deploy the legs.
It’s not the primary mission objective, and the company gives it only about a 30 percent or 40 percent chance of working, but it expect to gather valuable information from the exercise.
“These tests are an important step towards our end goal of putting people on other planets,” Shanklin said in an email. “So the data we gather here is key.”
This article originally appeared on Recode.net.