Sir Richard Branson's lofty ambitions to explore the limits of Earth — in both directions — have been put on ice. After Virgin Galactic's SpaceShipTwo crashed during testing earlier this year, company representatives have confirmed that Virgin Oceanic's goal of diving to the deepest part of the ocean has been put on indefinite hold.

Virgin Oceanic set out a grand goal when it was first announced in 2011. The project aimed to use an 18-foot deep-sea submarine to "fly" along the floor of the world's deepest oceans. The plan was to carry out five dives — one each to the deepest points of all five of our planet's oceans — in the span of two years. Branson himself intended to pilot the sub's second mission, to the Puerto Rico trench in the Atlantic Ocean.

But the Virgin Oceanic team lost to James Cameron and his DeepSea Challenger submarine in 2012, when the movie director set a solo world record and reached the bottom of the Mariana Trench, 5.1 miles beneath the surface. Branson had hoped that his team instead would be the first to reach the ocean's deepest point since the bathyscaphe Trieste in 1960. Once there, the submarine's pilot would "fly" along the surface of the ocean floor like a dolphin or manta ray for nearly six miles. But Virgin Oceanic's submarine, the DeepFlight Challenger, failed preliminary stress tests, raising concerns that it would not survive a trip to the Mariana Trench, let alone four other deep-sea missions.

James Cameron beat the Virgin Oceanic team to bottom of Mariana Trench

According to The Telegraph, the submarine's manufacturer, DeepFlight, never intended for the vessel to make multiple dives, and it pulled out of the project after Virgin announced plans to sell $500,000 tickets to the bottom of the ocean for amateur explorers. With concerns about the sub's durability and without DeepSea's expertise, it seems Virgin Oceanic slowly lost steam.

The project's website has been offline since at least this summer, and there has been no word on the mission for well over a year. A spokesperson confirmed to The Telegraph that the "project has been put on ice while we look at other technology that works," noting the safety concerns of the DeepFlight sub. He added, however, that "[Virgin Oceanic] remains our name, so no doubt we will revive it."

This past August, Branson published a letter online that seemingly cemented the end of the Virgin Oceanic program. He wrote, "Starting new ventures takes a 'screw it let's do it' attitude," but "business is also about knowing when to change tack." He then explains how Virgin Oceanic has shifted its goals to "democratize access at reduced cost and increased safety." It's not clear what the future of Branson's deep-ocean dreams are, but the idea is certainly still in the back of his mind. As he writes: "We are all still highly passionate about exploring the bottom of the ocean."