Orienspace, one of China's leading private rocket makers, launched nine satellites from a ship in the East China Sea off Shanghai on Wednesday, marking the fourth flight of its Gravity 1 rocket and the country's latest sea-based launch.

The rocket lifted off at 6 am from a launch service ship off the coast of Shanghai and soon placed the satellites — eight in the Spacesail Constellation network and one experimental craft — into their preset orbits.

This mission set national records for overall payload weight and orbit altitude of any sea-based launch ever done in this country, with a combined payload weight exceeding 3 metric tons and an orbit height of 800 kilometers, according to Orienspace.

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As China's annual space launches continue to climb steadily, its launch paradigms keep pushing beyond traditional boundaries. Sea-based launches have evolved from a supplementary option into a key pillar of the nation's space endeavor.

To date, China has performed nearly 30 sea-based launches, involving four types of rockets built by both State-owned and private enterprises. These launches placed more than 170 satellites into space.

All four of Gravity 1's launches took place at sea — the first two from the Yellow Sea and the last two from the East China Sea.

Wednesday's mission was also the first time for Gravity 1, now the biggest and most powerful solid-propellant rocket in the world, to deploy satellites for the Spacesail Constellation, one of the two massive internet networks China is constructing in space.

With a liftoff weight of 405 tons and a liftoff thrust of 600 tons, the rocket is capable of sending payloads weighing up to 6.5 tons into low-Earth orbit or 4.2 tons into a typical sun-synchronous orbit at an altitude of 500 km, according to the company.

Bu Xiangwei, CEO of Orienspace, said that his engineers are developing a larger, reusable liquid-fuel model called Gravity 2, and plan to perform its debut flight soon.

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"The new type will be capable of transporting 21.5 tons of payloads to a low-Earth orbit, significantly lowering launch costs. Gravity 1 and Gravity 2 will complement each other, and can contribute to establishing a reliable, practical space access capability and supporting the large-scale utilization of low-orbit resources," he said on Wednesday.

On Tuesday, LandSpace, another private space enterprise, launched its ZQ 2E methane-propelled rocket for the sixth time from the Jiuquan Satellite Launch Center in Northwest China, deploying 10 Spacesail Constellation satellites into their preset orbit.

The two launches indicated that Spacesail, a Shanghai-based satellite operator aiming to build a Starlink-like network, has begun to entrust private players with its satellite deployment missions, which had previously gone only to State-owned contractors.

Contact the writers at zhaolei@chinadaily.com.cn