Blue Origin is aiming to launch its New Shepard rocket on Sunday, founder Jeff Bezos said in a tweet.

Bezos, who founded the company and invests $1 billion each year into Blue Origin from selling Amazon stock, said the Sunday launch window will open at 9:30 a.m. ET. He added that "livestream info" will be coming soon.

@JeffBezos: Launch preparations are underway for New Shepard's 8th test flight, as we continue our progress toward human spaceflight. Currently targeting Sunday 4/29 with launch window opening up at 830am CDT. Livestream info to come. @BlueOrigin #GradatimFerociter

This will be Blue Origin's first flight this year. In December, its seventh New Shepard mission launched, landed and successfully deployed the unmanned Crew Capsule 2.0. It was the company's first launch in 14 months.

Sunday's flight is a continuation of Blue Origin's progress toward sending humans to suborbital space. CEO Bob Smith told CNBC last week he hopes the company will be launching tourists to space on New Shepard this year. He cautioned that the company will only "go when we're ready."

"We want to make sure it's completely safe for our passengers," Smith said.

New Shepard — named after the first American in space, Alan Shepard — launches vertically from the company's facility near Van Horn, Texas. In the seventh test flight, New Shepard's booster reached nearly 61 miles above sea level before the capsule separated. The booster than returned to land on a concrete pad, smoothly coming back to Earth at about 7 miles per hour.

The capsule later touched down on the desert floor at 1 mile per hour. The capsule is designed to hold six astronauts. With its large windows, Crew Capsule 2.0 is built to make it cheaper and easier for humans to experience weightlessness on the edge of space. After disconnecting from New Shepard's booster, the capsule glides in space at three times the speed of sound for a few minutes before gravity pulls the craft into a free fall. Three parachutes and a retrothrust system slow the capsule before touchdown.