Welcome to the Rotating Target Source Website!
This website will tell you all about how the new RTS system works, what
ADR and x-ray calorimetry are, a project timeline and student bios, and
What is a Rotating Target Source anyway?
During the summer of 2004, six Olin College students were hired by the
NASA Goddard Space Flight Center to improve their Rotating Target Source
(RTS), a box enclosing a rotating wheel that emits characteristic x-rays
used for calibrating an x-ray calorimeter. An adiabatic demagnetization
refrigerator (ADR) linked with an x-ray calorimeter was set to launch
in February 2005 from Japan, and this RTS would be used to calibrate it.
Before the project began, researchers at Goddard drove the motor inside
the RTS with a simple power supply. When they wanted to spin to a certain
point on the wheel, they turned on the power supply until the wheel was
in the right position. If they overshot, they had to go back around again.
They could never be exactly sure where they were and had little accuracy
in their control.
The Original RTS Machine (photographed at Goddard)
The Olin students were given the opportunity to change this by designing
a system that would rotate the wheel to exactly the right position at
any given moment. This was achieved with a motor control amplifier (MCA),
a shaft encoder, and a Macintosh. In the end, the NASA researchers had
a simple C program they could run from the Terminal of Mac OS X that gave
them the ability to immediately rotate to any position on the wheel, jog
the wheel clockwise or counterclockwise, or spin the wheel at a constant
rotation. Due to launching deadlines, the RTS was immediately flown to
Japan for ADR calibration, where it performed its job as defined. It was
a great opportunity for the Olin students to work on something of practical
application that covered so many technical areas.
Olin Students and Faculty in a Goddard Clean Room
So, what's an ADR?
Good Question. You should probably check that out at the