United Launch Alliance (ULA) is gearing up for a Vulcan launch tonight from SLC-41, USSF-106. Liftoff is set between 7:59 and 8:59 p.m. Eastern Daylight Time (2359–0059 UTC). And, if weather and timing permits, the launch may come with a bonus: a jellyfish plume, one of the most spectacular sights a launch spectator can see.

The weather looks favorable, with an 80% chance of conditions being acceptable through the launch window. The primary concerns include cumulus clouds, lightning potential, and surface electric fields. This is of course a common scenario for late-afternoon summer launches on the Space Coast. Final launch preparations by ULA and the Space Force, including the launch vehicle readiness review, are complete and “GO” for tonight.

Launch Time Is Near Local Sunset

If the skies cooperate and if the timing is just right, one of tonight’s most awe-inducing side effects could be a “space jellyfish”, a glowing, jellyfish-shaped plume formed by sunlight illuminating rocket exhaust at high altitude, while the ground below remains in twilight or darkness.

Here’s how it works:

• Timing is critical: Launching during twilight means the rocket ascends into sunlight while observers are in shadow. That’s because on the ground, the sun is below the horizon but is still visible in the ultra high altitudes a rocket travels through on its way to space. That’s simple geometry: the angle to the horizon is different for the rocket.
  
• Clear Skies: If low clouds are between the spectator and the rocket, they won’t see much.
  
• High-altitude expansion: If you have seen only a few launches, you probably remember the phase towards the end of the first stage’s part of the flight where gases spread into a broad, diffuse cloud that forms a conical shape behind the rocket. This is not the Max-Q contrail, something common to most rockets, instead, it happens very high in the sky when the rocket’s is mostly outside of Earth’s atmosphere.
  
• Optical spectacle: Because it is still in sunlight, the rocket plume is an illuminated cloud that takes on a jellyfish-like shapes, maybe with tendrils trailing behind, formed by thinner exhaust streams.
  
• Darkness: the relative contrast between the ground and the sky makes this phenomenon highly visible to launch spectators.

Details

Mission	Vulcan VC4S | USSF-106
Organization	United Launch Alliance
Location	Cape Canaveral SFS, FL, USA
Rocket	Vulcan VC4S
Pad	Space Launch Complex 41
Status	Go for Launch
Status Info	Current T-0 confirmed by official or reliable sources.
Window Opens	Tuesday, 08/12/2025 7:59 PM EDT
Window Closes	Tuesday, 08/12/2025 8:59 PM EDT
Destination	Geosynchronous Orbit
Mission Description	USSF-106 is a mission for the United States Space Force deploying payloads—including NTS-3 (Navigation Technology Satellite 3), a demonstrator of a reprogrammable navigation signal generator—directly into GEO.
Information current as of: August 11, 2025, 12:00 PM EDT

Launch dates and liftoff times are subject to change at any time.

Trajectory

Slightly south from due East:

Weather

The 45th Weather Squadron of Space Launch Delta 45 estimates an 80% chance of acceptable launch conditions throughout the hour-long window:

Online Viewing

ULA  will have a livestream of the launch on their website: USSF-106. 

Spaceflight Now will have coverage of the launch starting about one hour before liftoff on Youtube: link

For official updates regarding launch times, ULA’s website is the best source of information. Look for the Live Updates section: USSF-106

Remember that there is a delay between a launch stream and the actual countdown clock. That is simply because of physics: it takes time for the signal to travel from the launch site, through the Internet, and back down to your phone, resulting in a five to fifteen-second delay.

Next Space Flight an app for iOS and Android phones, has a real-time countdown clock that is accurate to a second, give or take. The app is free. Search the App Store or Google Play. They are also on the web: nextspaceflight.com.

Launch Viewing: In Person

The best free options are available for spectators: Titusville parks on Washington Avenu / US-1 are your best bets: Space View Park, Sands Park, Rotary Riverfront Park, Kennedy Point Park, etc. Jetty Park is also good, as are the pullouts on 528W near the Banana River Bridge.

The Space Bar will be open through the launch window. Restaurants in Port Canaveral, specifically Gators Dockside, Fishlips and Grills Seafood should have good views after the rocket clears obstructions.