# Deluge Days (DD-594)

> NASA's Stennis Space Center in Mississippi tests rocket engines and stages by bolting them to giant stands and firing them in place. Because the hardware doesn't move, the exhaust, which NASA says can reach 6,000 degrees Fahrenheit (about 3,300 degrees Celsius), pours into the same flame deflector for the whole test. Water keeps it from melting. Stennis's high-pressure industrial water system draws on a 66-million-gallon reservoir. For the Space Launch System core stage's Green Run tests in 2020 and 2021, the B-2 stand could receive 335,000 gallons a minute at 300 psi, enough to fill an Olympic pool in about two minutes. Most of it cooled the exhaust through the deflector, and about 87,000 to 92,000 gallons a minute formed a curtain of water to damp noise and vibration. A typical 500-second RS-25 engine test uses about 5 million gallons. Launch pads use water too. At Kennedy Space Center's Pad 39B, the ignition overpressure and sound suppression system dumps about 400,000 gallons in under 30 seconds, peaking around 1.1 million gallons a minute. NASA says SLS produces about 176 decibels at liftoff. The footage looks like a pad water-flow test, with columns of water erupting in front of a steel launch structure.

- Department: Space (also Tech)
- First published: 2025-06-12
- Last updated: 2025-06-12
- Permalink: https://detailenjoyer.com/case/deluge-days/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-594-F01**: The B-2 test stand at Stennis can receive 335,000 gallons of water a minute. _(Write-up · Exhibit B (335,000 gallons a minute))_
- **DD-594-F02**: A typical 500-second RS-25 test at Stennis uses about 5 million gallons of water. _(Write-up · Exhibit D (5 million gallons a test))_

## Write-up

Rocket tests run on rivers of water. Stennis's B-2 stand can take 335,000 gallons of water a minute.

1. **Fired in place**: Stennis bolts engines to test stands, so the exhaust hits the same deflector for the whole burn.
2. **335,000 gallons a minute**: The B-2 stand's water system can deliver 335,000 gallons a minute at 300 psi.
3. **Curtains for sound**: Part of the flow sprays a water curtain to damp noise and vibration.
4. **5 million gallons a test**: A typical 500-second RS-25 test uses about 5 million gallons of water.
5. **At the launch pad**: Pad 39B's sound suppression system releases about 400,000 gallons in under 30 seconds.

## Related case files

- [Starbase (DD-582)](https://detailenjoyer.com/case/starbase/): I paired it with another rocket site where water deluges matter
- [Baikonur Cosmodrome (DD-570)](https://detailenjoyer.com/case/baikonur-cosmodrome/): I linked another launch site with its own infrastructure
- [heat. (DD-595)](https://detailenjoyer.com/case/heat/): I linked the water that cools launch pads

## Reel vs. record

- **Note**: 'Acoustic energy exceeding 300 decibels': I can't support that. NASA puts SLS at about 176 decibels at liftoff, and sound in air can't really go much past about 194 decibels before it stops behaving like a normal sound wave. 300 decibels isn't physically possible here.
- **Note**: 'Millions of gallons per minute': I'd scale that back. Stennis's B-2 stand gets up to 335,000 gallons a minute. The Pad 39B launch system peaks around 1.1 million gallons a minute, but only for seconds.
- **Note**: 'Temperatures from thousands of degrees Celsius': fair. NASA cites exhaust up to 6,000 degrees Fahrenheit, about 3,300 degrees Celsius.
- **Note**: My Reel vs. Record note: the footage looks like a launch pad water-flow test, not a Stennis engine test. I treated it as an exemplar of the same idea.

## Video: Deluge Days: Rocket Tests Run on Rivers of Water

- Duration: 21.3 s · Published: 2025-06-12
- File: https://detailenjoyer.com/assets/videos/DK0gtujxBGc.mp4

### Transcript

DID YOU KNOW? NASA pumps vast amounts of water during rocket tests to protect equipment and ensure safety. At facilities like the Stennis Space Center, rocket engines generate extreme heat and acoustic energy, exceeding 300 decibels. A high volume water deluge system sprays millions of gallons per minute to cool exhaust plumes, reducing temperatures from thousands of degrees Celsius to prevent damage to the test stand. NOW YOU KNOW!

## Questions & answers

**Q: Why do test-stand engines need so much cooling water?**  
A: Without water, the flame deflector could melt. _(Source: Write-up · Exhibit A (Fired in place) · NASA: NASA Stennis Completes Key Test Complex Water System Upgrade; NASA APPEL: Historic Test Stand at Stennis Points Way to the Moon (2019))_

**Q: How much water a minute can Stennis's B-2 stand receive?**  
A: At 300 psi. _(Source: Write-up · Exhibit B (335,000 gallons a minute) · NASA APPEL: Historic Test Stand at Stennis Points Way to the Moon (2019))_

**Q: What does the water curtain around a test stand do?**  
A: It protects the hardware from acoustic damage. _(Source: Write-up · Exhibit C (Curtains for sound) · NASA: NASA Stennis Completes Key Test Complex Water System Upgrade; NASA APPEL: Historic Test Stand at Stennis Points Way to the Moon (2019))_

**Q: About how much water does a typical 500-second RS-25 test use?**  
A: It all comes from a 66-million-gallon reservoir. _(Source: Write-up · Exhibit D (5 million gallons a test) · NASA: NASA Stennis Completes Key Test Complex Water System Upgrade)_

**Q: How much water does Pad 39B release during a launch?**  
A: In under 30 seconds. _(Source: Write-up · Exhibit E (At the launch pad) · NASA: Pad 39B Water Flow Test Comes Through Loud and Clear (2019); NASA: Launch Pad 39B)_

## Sources

- [NASA: NASA Stennis Completes Key Test Complex Water System Upgrade](https://www.nasa.gov/centers-and-facilities/stennis/nasa-stennis-completes-key-test-complex-water-system-upgrade/)
- [NASA APPEL: Historic Test Stand at Stennis Points Way to the Moon (2019)](https://appel.nasa.gov/2019/08/26/historic-test-stand-at-stennis-points-way-to-the-moon/)
- [NASA: Pad 39B Water Flow Test Comes Through Loud and Clear (2019)](https://www.nasa.gov/centers-and-facilities/kennedy/pad-39b-water-flow-test-comes-through-loud-and-clear/)
- [NASA: Launch Pad 39B](https://www.nasa.gov/humans-in-space/exploration-ground-systems/launch-pad-39b/)

## Cite this case file

Easterling, Marcus. "Deluge Days." The Detail Department (DetailEnjoyer), case file DD-594, last updated Jun 12, 2025. https://detailenjoyer.com/case/deluge-days/