Launching rockets can be either a very, very dirty business or a pretty clean one, depending on the kind of fuel you use. The shuttle’s solid boosters are filled with a rubbery mix made up of ammonium perchlorate, aluminum, iron oxide, epoxy and a polymer bonding agent. If you think setting all that on fire would produce some nasty exhaust, you’re right. The Saturn V moon rockets used a mix of kerosene and liquid oxygen in their first stages, which produced it’s own air-fouling smoke. The second and third stages, however, were fueled with liquid oxygen and liquid hydrogen, releasing mostly flame and steam. The rockets that would be used for launching tourists on suborbital missions would be filled with some kind of hydrocarbon fuel which, like the kerosene in the Saturn V, would act as a pollutant.

To conduct its calculations on the atmospheric impact of recreational rocketry, the AGU proceeded on the assumption that the space tourism industry is correct when it projects that it will be launching about 1,000 vacation rockets per year by 2020. That’s not an entirely unreasonable prediction since Branson is by no means the only entrepreneur in the game. If that ambitious goal is met, the first and biggest concern would be the amount of soot the engines would produce. One thousand commercial launches would produce 10 times the soot emitted by government and private rockets today—and that presents serious problems.

Since particles of soot are black, they absorb rather than reflect away heat and light. Soot  from rockets poses a special danger since it is emitted far higher in the atmosphere than 0ther sources of air pollution. “Rockets are the only direct source of human-produced compounds above 14 miles [22.5 km],” said the paper’s chief author Martin Ross in a statement.

In the case of vacation rockets, this would mean a layer of accumulated soot in the stratosphere about 25 miles (40 km) high, or three times the altitude at which commercial airlines fly. The AGU’s computer models showed that by blocking sunlight, the soot could actually cool much of the surface of the planet by 1.2ºF (.7ºC), which seems like a good thing in the face of global warming. However, it would warm Antarctica by 1.5ºF (.7ºC), which is exactly what the rapidly melting southern ice does not need. Worse, soot that’s been deposited 25 miles high can hang around in the atmosphere for years, unlike soot from factories, coal-fired power plants and airliners, which precipitates out in as little as a few days or as much as a few weeks, depending on quantities and circulation patterns. Read more at ecocentric.blogs.time.com

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

America is a land of long distances, of thousands of virtually empty square miles of prairie, farmland and baking desert and frozen tundra.

US cities sprawl on a level unseen in Europe, Canada, and Australia, a consequence of transport priorities that have long favoured motor vehicles. And in all but a handful of US cities, it is virtually impossible to get by without a car.

But in recent years, amid widespread concern about US dependence on foreign oil, high petrol prices, signs of global warming and an obesity epidemic, a number of US cities have taken steps to increase bicycle usage.

These cities hope that by adding relatively low-cost bicycle lanes, bike parking and bike sharing programmes and making other city plan adjustments, they can lessen traffic congestion, reduce the strain on public transport, and promote healthier citizens.

Jim Sebastian, head of Washington DC’s bicycle and pedestrian programme, says his goal is to make the nation’s capital “one of the most bike friendly cities in the country”.

Portland – 5.96% Minneapolis – 4.27% Seattle – 2.94% Sacramento – 2.72% San Francisco – 2.72% Washington – 2.33% Oakland – 2.15% Tucson – 2.04% Albuquerque – 1.75% US – 0.55% Read more at www.bbc.co.uk

AMTRAK, America’s government-owned passenger rail company, has had a good recession. Ridership and ticket sales have steadily increased—presumably as people realise that comfortable seats, city-center-to-city-center travel, and less security theatre are all good things. Amtrak’s fiscal year 2010 continued the trend. The company carried 28.7 million riders, up 5.7% from FY 2009, and revenues from ticket sales were $1.74 billion, up 9% from last year. Almost 40% more people rode Amtrak this year than did in 2000.

Ridership along the corridor was up 4.3%, while ridership on the corridor’s “high speed” Acela trains was up 6.5%. (Since business travellers favor the Acela, the good numbers there are a sign that business travel is fuelling Amtrak’s growth.) “Amtrak now enjoys a 65 percent share of the air-rail market between Washington and New York and a 52 percent share of the air-rail market between New York and Boston,” the company said in a press release [PDF]. Read more at www.economist.com