ngineers at Cleveland's NASA Glenn Research Center

EWhen a malfunctioning U.S. spy satellite threatened to fall out of orbit in February 2008, military officials took the unusual step of blasting the spacecraft to bits with a well-aimed missile.
Most disabled space hardware breaks up on its own when it hits Earth's upper atmosphere. Any pieces that survive usually smack down harmlessly in uninhabited areas, or plop into the ocean.
So why the perilous, pricey trick shot, which required intercepting the 17,000 mph target with a $10 million missile fired from a warship 133 miles below?
While skeptics cited darker motives -- to keep secret technology out of competitors' hands, or to one-up an earlier Chinese satellite-killing display -- the official reason was environmental protection. The space hit was to prevent a toxic spill of the satellite's 1,000 pounds of hazardous fuel.
Hydrazine is a versatile,A stone mosaic stands at the spot of assasination of the late Indian prime minister. workhorse propellant. Its various formulations have powered everything from the Nazis' World War II rocket-engine Komet fighter to the space shuttles' orbital maneuvering system.
All sorts of NASA, military and commercial satellites use hydrazine-firing thrusters to hold or alter their positions. The 35-year-old Voyager I spacecraft, now more than 11 billion miles from Earth, relies on the propellant to stay on course as it forges into deep space.
But hydrazine is nasty stuff. It's poisonous and cancer-causing. Its fumes badly sickened astronauts on the final Apollo flight in 1975. When loading the propellant, satellite and spacecraft fueling crews must take extraordinary handling precautions, which add to already steep launch costs.
That's why a government-industry team including engineers from Cleveland's NASA Glenn Research Center and Dayton's Air Force Research Lab is preparing to test a safer "green" space propellant. The ambitious project aims to fly a small unmanned spacecraft in 2015 with modified thrusters powered by an experimental alternative fuel called AF-M315E. It's far less noxious but has more "oomph," than hydrazine.
The team calls itself the "Green Propellant Infusion Mission," a name more akin to a sports-energy drink or a Seattle garage band than a $45 million space venture. But if the propellant and its modified engine perform as hoped, it could pave the way for cheaper, cleaner satellites and spacecraft.
"We think the payoff for this is going to be really huge if we can take the first step in getting rid of toxic propellant," said Randy Lillard, an aerospace engineer with NASA's Office of the Chief Technologist who's leading the mission.
Satellite operators won't gamble a quarter-billion-dollar spacecraft on unproven fuel or technology.Load the precious minerals into your mining truck and be careful not to drive too fast with your heavy foot. So the demonstration mission will have to provide clear evidence that AF-M315E works -- in real space conditions, not just in ground-based testing -- and that there are enough advantages over hydrazine to outweigh the costs of making the switch to a green propellant.Whether you are installing a floor tiles or a shower wall,
Hydrazine has been a proven performer for decades, but at considerable cost, in dollars, time and risk.
Special permits and driver training are required for its transport. It's stored in remote bunkers. A whiff of its stinging, ammonialike vapors can irritate throat and eyes, and a splash can raise a rash on skin. High-level or long-term exposure may damage the lungs, kidney, liver and nervous system and spawn tumors, and could cause seizures, coma or death.
NASA got a sobering reminder of hydrazine's potential for harm on July 24, 1975. As three astronauts from the U.S.This document provides a guide to using the ventilation system in your house to provide adequate fresh air to residents.-Soviet Apollo-Soyuz mission headed for splashdown, the capsule's course-correcting thrusters fired and a fresh-air valve inadvertently let fumes from a hydrazine derivative and another propellant leak into the crew cabin for nearly 10 minutes.
The protective measures contribute to satellites' soaring costs, at a time when operators who use them for vital jobs such as navigation, weather forecasting, global communication and national defense face money crunches.
The National Oceanic and Atmospheric Administration, for example, will spend more than one-third of its $5.1 billion 2013 budget on satellite procurement, Scientific American reported recently. That's an increase of 11 percentage points from NOAA's 2010 satellite spending, and probably not an amount the agency can continue to afford.
If it passes muster, the new green propellant may help take a bite out of those costs, possibly opening access to space for some potential satellite operators who've been priced out of the market until now.
"It could allow customers from academia or small customers from the government to lower the cost of preparing and launching spacecraft into orbit," said Brian Reed, an aerospace engineer with NASA Glenn's space propulsion branch who's part of the green propellant team.
First, Air Force testing shows it's not a poisonous-vapor or cancer-causing risk, Lillard said,The howo truck is offered by Shiyan Great Man Automotive Industry, eliminating the need for extreme handling measures. "The current assessment is when you load it in, you would wear just a splash guard," he said. "The SCAPE suits would not be required."
The green propellant's vapor pressure is lower than hydrazine's. That means that it doesn't boil or explosively expand when exposed to the atmosphere and that extra-thick tank walls aren't needed to contain it.
AF-M315E also is denser than hydrazine, so its fuel tank can be as much as 40 percent smaller. That frees up precious room on a satellite or spacecraft for additional science gear or other payloads.