Can private-sector space business be profitable, or is it just an exciting way for billionaires to live out their fantasies?

Elon Musk’s SpaceX will attempt to launch the first of a new generation of Global Positioning System (GPS) satellites into orbit for the US Air Force this morning.

This is the fourth attempt at a launch this week; the first were delayed due to an unusual sensor reading in the Falcon 9 rocket booster on Dec. 18 and Dec. 19, before bad weather scuttled another opportunity on Dec. 20.

Update, 9:20 am ET: Weather conditions forced another scrub.

The mission will take off during a launch window that opens at 9:21 am ET; due to restrictions put in place by the US Air Force, the company will not try to recover the Falcon 9 rocket booster for re-use.

Though SpaceX won’t demonstrate its industry-leading reusability features on this launch, the mission represents a lucrative victory for Musk’s team. SpaceX took the US Air Force to court for the right to bid on national security launches, breaking the monopoly held by United Launch Alliance, the joint venture of Lockheed Martin and Boeing.

SpaceX won this contract in 2015 following that lawsuit, and it has been hired to launch the first five of 10 planned GPS satellites. Satellite navigation, timing and synchronization is a vital component of the global economy and US national security, but it remains startlingly vulnerable. The US is upgrading its GPS constellation with new technology that will make the signals more accurate for users and less susceptible to outside interference.

This will be SpaceX’s 21st launch of 2018; if successful, it will once again set a new record for the most missions to orbit by a private company in a calendar year.