Elon Musk’s SpaceX is gearing up to launch the highly secretive ‘Zuma’ satellite – a mysterious payload commissioned by an undisclosed branch of the US government.

It was initially slated to launch in November, but is now set to take place this Thursday, with the launch window opening at 8pm (EST).

So far, a weather report shows conditions will be ‘excellent’ for lift-off at the Cape Canaveral launchpad in Florida.

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SpaceX is poised to launch an unmanned cargo ship carrying a secret payload into orbit. The mysterious cargo will launch atop a Falcon 9 rocket (file photo) at around 8:00pm ET (1:00am GMT) from Cape Canaveral

SPACEX'S LATEST ACHIEVEMENT On December 15, SpaceX made history by launching both a recycled orbital rocket and spacecraft for the first time. The unmanned Falcon originally flew in June, with the firm's 11th resupply mission for the ISS. And, the Dragon capsule made a space station shipment in 2015 in support of the sixth cargo mission. The Dragon capsule was towing nearly 5,000 pounds of supplies to the ISS – including a barley experiment for Budweiser. Once again, the firm’s Falcon 9 first stage managed to land itself back on the launchpad, touching down gently to mark its second successful trip to and from space, with just a six-month turnaround. Advertisement

The satellite is a low-Earth orbit satellite, meaning it would orbit within the boundaries necessary for spy and military communication satellites, according to Sky News.

But, very little is known about the mission, codenamed Zuma, as no commercial or government entity has claimed it.

Even the branch of the US government responsible for spy satellites, the National Reconnaissance Office, is public about payloads it launches via SpaceX, though it always keeps the details classified.

It’s set to launch this Thursday atop a Falcon 9 rocket, which will eventually return to a different launchpad at the facility.

The launch was arranged by Northrop Grumman, who has revealed little details on its purpose, according to Space.com.

‘The Zuma payload is a restricted payload,’ Lon Rains, communications director for Northrop Grumman’s space systems division, said in a statement in November.

‘Northrop Grumman is proud to be a part of the Zuma launch. The event represents a cost-effective approach to space access for government missions.’

The Zuma mission bares similarities to two other launches in the past, PAN and CLIO, launched in 2009 and 2014 respectively.

These missions were also secretive and unclaimed by any government entity.

The PAN satellite was used by the National Security Agency to spy on conversations routed through communications satellites above the Middle East, according to documents obtained by The Intercept last year.

Elon Musk (pictured) and his company SpaceX are hoping today's launch will mark the firm's 17th of 2017, already more than doubling last year's tally of eight

THE REUSABLE ROCKET RACE SpaceX made history in March when it achieved the first-ever reuse of an orbital-class booster, which CEO Elon Musk had deemed 'a huge revolution for spaceflight.' Reusable rockets would cut costs and waste in the space industry, which currently loses millions of dollars in jettisoned machinery after each launch. Russia, Japan and the European Space Agency are developing similar technology and are in testing stages. Jeff Bezos, the founder of Amazon.com and owner of The Washington Post newspaper, said in February that his private space firm Blue Origin expects to begin crewed test flights of the New Shepard, the company's flagship rocket, next year and begin flying paying passengers as early as 2018. The Indian space agency also hopes to develop its own frugal shuttle, as it seeks to cash in on a huge and lucrative demand from other countries to send up their satellites, after a successful test launch in February. Advertisement

In September, the US Air Force's X-37B program launched a secret robotic mini-shuttle via a SpaceX Falcon 9 rocket.

Once Zuma is on its way to orbit, part of the reusable rocket will fly back down to Earth, landing on a pad in Cape Canaveral, Florida around 10 minutes later.

While other rocket makers ditch the boosters at sea following orbital missions, SpaceX expects to reuse the booster to save time and money.