New Zealand space company Rocketlab has passed two major milestones on its journey to put satellites into orbit.

The company has finished "qualifying" its 3D-printed Rutherford engine and the second stage of its Electron rocket.

"Those are two major milestones, when you push everything to the limits and they perform as you expect," says chief executive Peter Beck.

"Qualifying the engine is a major milestone because it is the first time that anyone has 3D-printed an entire rocket engine and gone through the process to make sure it works, and at very high performance as well."

The second stage is also important because it not only carries the satellite payload, but also has all the guidance systems on board.

"First stage gets us through the soup and second stage we put the foot down, and that's what takes us through to orbit," Mr Beck says.

"So we separate at about six times the speed of sound and when we ignite we go from six times to 25 times the speed of sound."

Rocketlab plans to launch its Electron rocket into orbit to deliver small commercial satellites at 500km above Earth at a fraction of the cost.

It says it will cost about $4.9 million compared to the $130 million it currently costs to launch a rocket.

Rocketlab's already booked out 12 flights without having launched a single rocket.

A launch facility is being constructed in Gisborne on the Mahia Peninsla, and the company also has an agreement with NASA to use launch facilities in the United States.

Mr Beck says he is asked all the time when the first launch will be, but he says there isn't a definite date yet.

"We have a multiple test flight programme beginning later in the year and we have a minimum of three test flights to get out by end of this year, and then we start commercial operations at the beginning of next year."

Mr Beck says it's an interesting industry because unlike a cell phone or car, the tests can't be done in secret. If a rocket launches, everyone will know about it.

"The reality is that no matter whether it's a small programme or a billion-dollar government programme, the statistical reality is that 80 percent of all first flights fail," Mr Beck says.

Rocketlab has just employed its 100th rocket scientist, but says it already needs another 30.

Newshub.