Page 119 - International Space Station Benefits for Humanity, 3rd edition.

reduced particulate and nitrogen oxide emissions.
This could eliminate the need to burn diesel-fuel sprays,
which are notorious for pollutant production, according
to the researchers.
The FLEX investigation in the reduced gravity
environment of the space station provides new insight
into the mysteries of flames and fuel. Whether a candle,
campfire or some other fuel source, the combustion
process may be waiting for the right investigation to
illuminate more secrets. Microgravity research may
prove to be the tool that helps shine that light.

Space Station Technology
Demonstration Could Boost
a New Era of Satellite Servicing
A burning heptane droplet during the FLEX and
FLEX investigation on the ISS. The Robotic Refueling Mission (RRM) was built to
Image credit: NASA demonstrate much more than the clever ways space
robots can refuel satellites. RRM also demonstrated
how space robots can replenish cryogen, a type of
coolant, in the instruments of legacy satellites—
existing, orbiting spacecraft not originally designed
More recent FLEX experiments reveal similar two-stage to be serviced.
burning phenomena with n-octane and decane fuels.

While burning the heptane droplets in the CIR, the Delivery to Space Station and Installation
first stage had a visible flame that eventually went out.
Once the visible flame disappeared, the heptane droplet The RRM project included five specialized tools that
continued rapid quasi-steady vaporization without the Canadian dexterous robot Dextre used to perform
any visible flame. This ended abruptly at a point called several complex servicing tasks, including cutting lock
second-stage extinction. At this point, a smaller droplet wires, removing caps, opening valves, and replacing
was left behind. The droplet either experienced normal, electrical connectors. All these precision motion tasks
time-dependent evaporation or sometimes grew slightly were controlled by operators 322 km (200 miles) below
through condensation of vapor in the cloud that formed in Houston while the crew slept or performed other
upon extinction. important tasks.
The new findings have been published and are New hardware deliveries to the space station helped
available online in Combustion and Flame, the journal outfit the RRM module for a new set of operations.
of the Combustion Institute. This new discovery Dextre added two new task boards to the RRM that
will help scientists and engineers modify numerical included additional satellite cryogenic and electrical
models and better predict the behavior of flames,
fuel and combustion. It also has many long-term
implications both in space and on Earth. These findings
can help with development of new technology to RRM helps to usher in an era
reduce pollution and increase gas mileage in internal
combustion engines. Cool flame burning could also be of serviceable spacecraft that
used to partially oxidize the fuel for use in burners with breaks the paradigm of “one
reduced emissions and better control. and done,” thereby making
The Homogeneous Charge Compression Ignition
engine can replace spark ignition and can be used in spaceflight more sustainable,
any diesel engine, either stationary or for transportation. affordable and resilient.
By merging these two technologies, engines could have
the efficiency of burning diesel, while also providing

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