Launching a Space Force satellite can create a glowing cloud in the evening sky

If you watch the stars in the western hemisphere tonight and look up at just the right time, you may see something that will seem quite strange: a small round cloud of light that will quickly increase to about the apparent size of the full moon before finally disappearing in a few minutes. 

What you just saw is not some strange atmospheric phenomenon, but a fuel dump from the US Space Force (USSF) mission, which was launched earlier today on a United Launch Alliance (ULA) Atlas V 511 rocket from Space Launch Complex 41 at Cape Canaveral. Space Force station in Florida.

The launch, which took place exactly on schedule at 14:00 Eastern Standard Time (19:00 GMT), delivered two satellites to the US Navy Space Systems Command (SSC). The mission, called USSF 8, will launch two identical satellites of the Geosynchronous Space Situational Awareness (GSSAP) Program - GSSAP 5 and GSSAP 6 - directly into a near-geosynchronous orbit of approximately 22,300 miles (36,000 kilometers) above the equator.  

According to the ULA flight profile, the first of the two satellites (GSSAP 5) will be launched into geostationary orbit 6 hours and 35 minutes after launch, and the second satellite (GSSAP 6) will be launched 10 minutes later.

Seven hours, 11 minutes and 40 seconds after launch, the second stage of the Centaur will dump unused (excess) fuel into space. Dumping excess fuel is a common practice for all Centaur launches using a launch vehicle. This happens after the separation of the satellite; fuel flowing from the upper stage of the Centaur rocket. 

As it turned out, the timing of this event is perfect for creating a sky show for most of the Western Hemisphere. When the Centaur releases excess fuel, night will fall over North and South America. But the Centaur at an altitude of about 22,300 miles (36,000 km) will be under sunlight, and so the fuel will reflect sunlight visible from the Ground.  

On Twitter, a diligent observer of the satellites of the Siz Bassa provided a significant amount of information about the visibility of the fuel dump:

Bassa compares the appearance of a fuel dump to "a bright nebula, perhaps the size of a full moon in the sky."

"The cloud should be visible to the naked eye, and with binoculars or a telescope you can see how it grows and changes shape," Bassa added.

Fuel discharge is expected at 21:11:40 Eastern Standard Time (18:11:40 Pacific Standard Time). To the naked eye, it should suddenly appear to be an expanding round comet-like cloud about 10-15 degrees to the west (or to the right) from the bright bluish zero-magnitude star Rigel in the constellation Orion. Your clenched fist at arm's length measures about 10 degrees, so about "one or one and a half fists" to the right of the Crossbar is where the cloud should appear.  

There have already been similar fuel discharges from satellites. On the evening of August 12, 1986, shortly after 22:00 Eastern European time (02:00 on August 13, GMT), countless people in the United States and Canada watching the Perseid meteor shower were surprised by the dumping of fuel from a Japanese ship. launch of the satellite that created the glowing cloud. 

And on September 1, 2004, the fuel discharge from the NRO-1 satellite, launched earlier in the day, was visible from the east of the United States and Canada.