'Extreme Programming' Controls Mars Lander Robot
Computerworld
(06/05/08) Gaudin, Sharon

Approximately 30 NASA engineers and
programmers work to write and test 1,000 to 1,500 lines of software code every
day that is sent to the Mars Lander, which is searching for elements that could
support life on Mars. Matthew Robinson, the robotic arm flight software engineer
at the Jet Propulsion Laboratory, says the team writes the code sequences to run
different parts of the Phoenix spacecraft, including the robotic arm, the
cameras and analysis equipment. A single mistake could cause the spacecraft to
sit idle for a day, wasting time that could be used to explore Mars. "It's a
challenge because we have a two- to three-day strategic plan, and then each day
that plan is refined," Robinson says. "You have to build 20 to 30 sequences, and
each can have 50 lines of code in it." The developers use the C programming
language to build their own software for a Linux operating system, and are
expected to be dealing with such extreme programming for approximately three
months, a fter which the drastically cold temperatures on Mars will cause the
Lander to freeze and stop working. Keeping the robotic arm and the rest of the
Lander running is a huge challenge. Robinson says a 3D elevation map was
recently used to write code to make the arm reach down and touch the ground. The
next day the arm was sent instructions to scoop some soil and hold it so
on-board cameras could take pictures of it, followed by another practice scoop
the next day.
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