Published: 2015-04-13 06:43:46
Updated: 2015-04-13 06:43:46
Posted April 13, 2015
By Tony Rice
When Italian astronaut Luca Parmitano was asked what he missed most during his stay aboard the International Space Station (ISS), it wasn't family or friends, it wasn’t food, it was coffee. He missed his espresso.
Among the 4,387 pounds of cargo aboard the uncrewed SpaceX Dragon capsule set to launch Monday is the espresso machine, dubbed ISSpresso, Parmitano would have liked to have as a member of expeditions 36 and 37 in 2013. The machine, designed by famed Italian coffee maker Lavazza and space food engineering firm Argotec, solves the complexities of brewing at the high temperatures and pressures required and does it safely.
Like any other espresso machine, ISSpresso passes 200 degree water through ground coffee at very high pressure, at least 9 bar (9 times atmospheric pressure at sea level) to be considered authentic Italian espresso. Here on Earth, gravity pulls the water through the coffee, something not possible in the microgravity of the space station. Instead, astronauts provide water from a pouch drawn from the ISS’s water recycling system (more on that later). That water is aspirated, pressurized and heated before passing through a coffee capsule. That capsule is not unlike those used by Keurig or similar machines you may have used to make your morning coffee. To ensure safety, the machine’s internal plumbing can withstand up to 400 bar. Coffee is pumped into a plastic pouch, and astronauts then drink from a straw.
The water that astronauts drink or use to make coffee or other drinks with comes from a recycling system. The ISS could not exist as it is today without this system as 40,000 very expensive pounds of water would need to be transported to the station each year just to keep a minimal crew of four supplied.
Instead, water is recycled from urine, from tooth brushing and hand washing, sponge baths (using about a gallon of water) and even by condensing humidity from the air. As the astronauts say, yesterday's coffee becomes today's coffee. It might sound disgusting, but water leaving the space station's purification machines will be cleaner than what most of us drink on Earth.
Long before the Dragon capsule arrives, all eyes will be on the rocket that boosted it. SpaceX is making a second attempt to land its Falcon 9 rocket on a floating platform off the coast of Jacksonville, Fla. Thrusters repurposed from oil rigs keep the platform in position, with a variance of about three meters, even during a storm. The first landing attempt was close but hydraulic problems in fins used for stability brought the rocket in at a steep angle, and it crashed into the platform.
Landing on the platform requires some complex acrobatics.
After the main engine cuts off and the second stage pushes the Dragon capsule into an orbit to chase down the ISS, the Falcon9 booster then flips via cold-gas nitrogen-powered thrusters and its main engines are then relit to stop its forward momentum. The rocket then burns three of nine main engines to slow the rocket from hypersonic speeds. While still traveling faster than three times the speed of sound, “grid fins” along the rocket body are deployed to provide additional control. As the landing platform grows closer, compressed helium deploys the landing legs, which were tucked alongside the rocket, and a single engine is burned to slow the vehicle to a soft landing. At least that’s how it is supposed to work.
The landing legs, grid fins, additional fuel and gasses required to operate the landing system add weight and cost to the launch. However the Falcon9 rocket is the most costly component in the launch. Achieving reusability of that booster would help bring down the cost of lifting payloads to orbit.
Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.