Elon Musk's SpaceX plans NASA test launch Saturday

NASA and SpaceX have completed thousands of hours of tests to prepare for this unmanned test flight to the International Space Station.

The Washington Post's Christian Davenport is among journalists who are gathering at Kennedy Space Center's launchpad 39A in Florida to witness a planned SpaceX test launch that is destined for the International Space Station.

The launch of an unmanned craft brings NASA closer to having astronauts depart U.S. soil for space, for the first time in almost eight years.

A lot is riding on this launch, particularly as the long-held fraternal relationship between America and Russia on space matters seems newly frayed.

From Davenport's Washington Post dispatch:

Although the Dragon spacecraft won't be carrying astronauts — only a mannequin named "Ripley" with sensors and about 400 pounds of cargo — the flight will mark a significant step toward the restoration of human spaceflight from U.S. soil since the space shuttle was retired nearly eight years ago.

The heat isn't just on SpaceX and Musk, who has drawn scrutiny from the SEC over his leadership of his electric car company, Tesla, but on NASA, as well. Years ago, it placed a bold bet on the private sector and outsourced human spaceflight to the International Space Station to two companies: SpaceX and Boeing. The companies won the contracts, worth a combined $6.8 billion, in 2014.

Since then, both companies have faced setbacks and delays as they struggled to meet NASA's rigorous safety requirements. But now NASA says they are poised at long last to make their first flights with humans this year — a timeline many in the industry believe may be optimistic given the immense challenge.

Since the space shuttle retired in 2011, NASA has had to purchase seats on a Russia spacecraft, the Soyuz. Those seats runs out by the end of this year, so if SpaceX and Boeing's spacecraft are not ready, NASA would have to purchase additional seats or face the prospect of not having an American astronaut on board the space station, in which the United States has invested about $100 billion.