Plume Power
The space shuttle's exhaust trail makes for a lovely sight on an April morning.
- AirSpaceMag.com, May 11, 2010
James Vernacotola
Video Gallery
Go For Launch!
Space shuttle Discovery gets prepped for flight—in just under four minutes.
It was a bridge worth returning to, and it yielded something new. Photographer James Vernacotola had stood on the Palm Valley Bridge, which crosses the Intracoastal Waterway near Jacksonville, Florida, to capture night, dawn, and dusk launches from NASA’s Kennedy Space Center, more than a hundred miles to the south. Most recently, he had come in the middle of the night on February 8, 2010, where he nailed an awe-inspiring time exposure of the space shuttle Endeavour rising from the launch pad 115 miles away (see “Sightings” Jun./Jul. 2010). That 4:14 a.m. launch was the last scheduled night launch of the shuttle program. Vernacotola went back a couple months later for the 6:21 a.m. launch of Discovery on STS-131. With the sky brightening in the east, and no moon or stars in the frame, it wouldn’t quite rival the STS-130 shot.
Think again. Six and a half minutes into the ascent, with the solid rocket boosters having long since fallen away but with its three main engines still cooking, the orbiter was suddenly high enough in the northeastern sky to be in sunlight. This revealed a gossamer plume of water vapor expelled by the burning of the liquid hydrogen and liquid oxygen propellants. The exhaust instantly condensed to ice crystals in the frigid vacuum of near-space almost a hundred miles high. Vernacotola swiveled his camera on its tripod and made this 15-second exposure (see a larger version here). “That’s the first time I’d ever seen anything like it,” he says. “When we first saw it, we were wondering if something was wrong. Now I suppose the vapor trail is always there, but maybe I’ve never seen it because it was never backlit by the sun like that.”
Four-time shuttle flier Tom Jones confirms these suspicions. He says that the plume gets lost in the fiery booster exhaust during the first two minutes, and would be too diffuse to be seen in daylight or darkness anyway. But the main engines continue to produce it until they shut down about eight and a half minutes after liftoff. Jones has seen the plume from inside the shuttle during ascent. “The steam from the nozzles, at high vacuum [occurring at high altitude] begins to creep up the side of the stack,” he says. “With no ambient pressure, the plume expands to engulf the [external fuel] tank and orbiter sides, so much so that the crew can see the flickering of the steam plume reflecting the luminosity at the engine nozzle through the top windows in the flight deck. The pulsing plume gets your attention—is it a fire?!!! Is everything OK back there? But it’s normal. Just unexpected to see your exhaust racing along with you.”
Related topics: Astronautics Rockets Shuttles 21st Century Aviation
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Comments (7)
I saw the plume from Discovery, STS-131, from my front porch in Clayton, NC. About 4 minutes after launch, after the solids had fallen away, I went out on my front porch and looked east, just for the heck of it. Just above the treeline I saw the shuttle engine output as a bright, fast moving point of light. This point of light was the nucleus of a bright "cometary" trail that dissipated rapidly along the Shuttle's path. It was quite a sight to see and an event I wish I had had my camera ready for. I only collect mission patches for the launches I see. I have a mission patch now for STS-131! I will miss watching our girls soar once they are retired.
Posted by Mark Ellis on May 21,2010 | 12:01 AM
Mark, I was going to post a comment, but it is almost exactly identical to yours! I, too, saw this vapor/ice plume following Discovery, from Fort Fisher, NC (near Wilmington). I had seen beautifully the launch of Endeavour a number of weeks earlier, rising over the Atlantic and under a slightly gibbous moon (if I remember correctly). For Endeavour, I had seen the ascent from about T+ 30 seconds to just before MECO. The SRBs put on quite a show, even from 400+ miles North.
For Discovery on STS-131, I didn't think I'd see much since the sun would soon be rising. How wrong I was! I only saw the last 4 seconds or so of the SRBs, then lost the shuttle in the haze for about a minute or so. I found it again coming under the moon, and another 45 seconds or so later, found the awe-inspiring vapor trail. I also thought for a split second that something was wrong, as it says the photographer in the article did! But just as soon as I thought that, I realized what I was seeing and it was oh-so-beautiful! Unluckily, my camera battery died seconds before the plume was visible! Rats! Also, like you said, I thought it looks just like the tail of a comet. As Discovery powered on, I saw distinctly the 3 dots of light in a small traingle-- the Space Shuttle Main Engines, and the vapor plume very definitely came in three streams. What a sight!
I've seen three launches from the Cape and two from 440-ish miles away in coastal NC, and every launch, no matter your distance from it, you notice something new and experience a majesty you've never known before. I, along with the rest of the country, will miss terribly these magnificent machines. You should have seen the sentiment of the 300,000-strong launch crowd at the Cape a little over a week ago for STS-132! What a launch! This new gap in America's human space flight will be a painful one.
Posted by Mark Smith on May 24,2010 | 08:49 PM
I, too, have been fortunate enough to watch a space shuttle launch from Kennedy. It's fantastic! Very exciting! But I also live in Nacogdoches, Texas, over which part of the Columbia tragedy occurred. Many of us heard it, many of us saw streaks in the sky that did not mean excitement. Never do I see a jet stream or hear or read about the shuttle missions without remembering that sad event.
Posted by Kathleen Davis on June 23,2010 | 12:31 PM
I was among the huge crowd in Titusville that watched STS-131 lift off in the darkness. After the boosters dropped off I shot great video of the plume spreading out in the vacuum. Looking right up the tail, you could see the three engines in the center and the tri-part symmetry of the plume around it. Then we were surprised as the top of the booster plume was lit by sunlight, creating wild iridescent patterns. It was all worth the all-night stake-out and subsequent traffic jam!
Posted by Gaylon Arnold on June 23,2010 | 11:46 PM
I live in the UK and have swallowed up everything to do with the shuttles, including the infamous 25th launch. What is goung to replace this marvelous piece of 20th cent. engineering?
Posted by Paul McCarthy on June 27,2010 | 09:26 PM
> What is goung to replace this marvelous piece of 20th cent. engineering?
The same thing that has replaced Concorde. Nothing.
Posted by Paul De Zan on August 27,2010 | 12:34 AM
On the night of September 22, 1993, I saw STS-51 (Discovery) fly over the Houston, TX, area during its night reentry. It was the most spectacular thing I've ever seen in the sky: the orbiter was a bright white dot moving at about Mach 15 or so, trailing a glowing stream of ionized air that was 60 to 90 degrees of arc long behind it. Didn't even think to take a picture, but the sight literally took my breath away. Discovery was about 200,000 feet in altitude, I determined afterwards, and there was a sonic boom (just a single one) a few minutes later.
Posted by Des Welch on December 17,2010 | 05:39 PM