Calculating Environmental Damage From Space Tourism Rockets 83
MithrandirAgain writes "A new study from several scientists at the Aerospace Corporation claims spaceships that rely on rubber-based fuel could help cause climate change. The fuel apparently expels a black carbon soot into the stratosphere when burned with nitrous oxide, which could be contributing to global climate changes, like shrinking the icecaps. However, the authors are careful about their work being an end-all study and are 'inviting others to take a look.' Virgin Galactic, whose SpaceShipTwo just made its first solo flight (and uses the type of fuel discussed in the study), is listening to the scientists' concerns. CEO George Whitesides said, 'I think we and others in the industry welcome the opportunity to talk about all of these issues.' SpaceShipTwo does use a hybrid engine 'because of its significantly lower environmental impact than other designs,' and Whitesides stresses, 'I think as we look at this more, we'll find the impact will be far smaller than that set out in the paper. In any case, I welcome the conversation.'"
I'm impressed ... (Score:3, Interesting)
However, the authors are careful about their work being an end-all study and are 'inviting others to take a look.'
A refreshing attitude ... that's how science is supposed to work. There have been far too many bombastic claims made about global warming.
Why warming and not cooling? (Score:5, Interesting)
Re:I'm impressed ... (Score:2, Interesting)
To be honest I think this study is environmental FUD. They are saying that 40,000 launches over 40 years can cause significant environmental change including 1.8 degree temperature shift (positive) at the poles.
The obvious question that comes to my mind is why do think that any significant amount of soot from the 1000 rockets launched this year would still be in the atmosphere in 40 years? Do they have any reason to suspect that it stays around that long? The thing that comes to mind for me with high level soot is volcanic eruptions and their effects are no where near that long lived (from what I can find on wikipedia, they usually only effect the weather for about 1 year).
Finally, again comparing to volcano's, the best data I can find for a volcanic eruption that changed the climate (1991 Pinatubo) suggests that it dumped 17 million tons of CO2. I know this is talking about rubber particulates and not CO2, but there's a big difference in magnitude between 17 million tons in a few days and 1.3 million tons over 40 years.
Re:Why warming and not cooling? (material matters) (Score:1, Interesting)
A quick google query and you can figure this out for yourself.
Volcanoes create a cooling effect due to the sulfur they spew into the high atmosphere.
Direct sulfur injection is actually a proposed geo-engineering solution to global warming.
http://www.livescience.com/environment/060727_inject_sulfur.html
Found the actual article... (Score:5, Interesting)
Careful now: FUD as we typically use it on Slashdot is doubt raised by pure rhetoric, in the absence of facts. These guys have actual *data*. You can question their assumptions, but they're not just using scary words.
The obvious question that comes to my mind is why do think that any significant amount of soot from the 1000 rockets launched this year would still be in the atmosphere in 40 years? Do they have any reason to suspect that it stays around that long?
I've found the original Geophysical Research Letter [agu.org] article (it's behind a paywall unless you're at an institution that subscribes to GRL, which I am).
They do *not* assume that the soot sticks around for 40 years: they include a settling time for the soot particles of a couple of years (details more complicated). But they run the model for 40 years to give the ocean and cryosphere time to adjust.
They use a detailed model of the interaction of sunlight with soot particles: this model was developed for studying nuclear holocaust scenarios. They make some assumptions here about the size and properties of rocket soot particles, but I don't see any red flags.
Finally, again comparing to volcano's, the best data I can find for a volcanic eruption that changed the climate (1991 Pinatubo) suggests that it dumped 17 million tons of CO2. I know this is talking about rubber particulates and not CO2, but there's a big difference in magnitude between 17 million tons in a few days and 1.3 million tons over 40 years.
Soot particles have a *very* different climate effect than CO2, it's apples and oranges.
Based on what I read in their article and on my personal experience as a climate modeling scientist, I can tell you that they're using the right computer model for the job, and their assumptions about soot input seem reasonable, and they're including all the relevant physics.
It should also be mentioned that the climate change effects they're predicting (1 polar temperature rise, 5-15% northern polar sea ice loss) are observable, but *much* smaller than the predicted changes from anthropogenic greenhouse gas emissions (up to 8C polar temperature rise, possible total loss of summer sea ice). But still, no joke.
Re:The reporting bugs me (Score:4, Interesting)
it still remains that no mechanism for the claimed climate changes has been described. It's just, "These guys ran their computer model and this is what they got." That's extremely unhelpful.
If you have access to AGU journals, you should read the original article [agu.org]. It's quite detailed about the mechanisms involved.
Even without the original article, the mechanism here really isn't rocket science. Black stuff in the atmosphere makes the planet absorb more sunlight and therefore heat up. Really simple. To go beyond mechanism to get a numerical estimate of climate change, you unavoidably need a model. And take it from me, the one they're using is a good one.
You're using a lot of breath to cast doubt on the results here, with far less justification for your conclusions than the Nature and Wired authors you're attacking.