**Omit Needless Bytes!**

**by Patrick Barry and Tony Phillips**

Now is an exciting time for space enthusiasts. In the history of the
Space Age, there have never been so many missions "out there" at once.
NASA has, for example, robots on Mars, satellites orbiting Mars, a
spacecraft circling Saturn, probes en route to Pluto and Mercury---and
four spacecraft, the two Voyagers and the two Pioneers, are exiting the
solar system altogether.

It's wonderful, but it is also creating a challenge.

The Deep Space Network that NASA uses to communicate with distant probes
is becoming overtaxed. Status reports and data transmissions are coming
in from all over the solar system---and there's only so much time to
listen. Expanding the network would be expensive, so it would be nice if
these probes could learn to communicate with greater brevity. But how?

Solving problems like this is why NASA created the New
Millennium Program (NMP). The goal of NMP is to flight-test
experimental hardware and software for future space missions. In 1998,
for instance, NMP launched an experimental spacecraft called Deep Space
1 that carried a suite of new technologies, including a new kind of
communication system known as Beacon Monitor.

The system leverages the fact that for most of a probe\'s long voyage to
a distant planet or asteroid or comet, it\'s not doing very much.
There's little to report. During that time, mission scientists usually
only need to know whether the spacecraft is in good health.

"If you don\'t need to transmit a full data stream, if you only
need some basic state information, then you can use a much
simpler transmission system," notes Henry Hotz, an engineer at NASA\'s
Jet Propulsion Laboratory who worked on Beacon Monitor for Deep Space
1.  So instead of beaming back complete data about the spacecraft's
operation, Beacon Monitor uses sophisticated software in the
probe's onboard computer to boil that data down to a single "diagnosis."
It then uses a low-power antenna to transmit that diagnosis as one
of four simple radio tones, signifying "all clear," "need some
attention whenever you can," "need attention soon," or "I\'m in big
trouble---need attention right now!"

"These simple tones are much easier to detect from Earth than complex
data streams, so the mission needs far less of the network\'s valuable
time and bandwidth," says Hotz. After being tested on Deep Space 1,
Beacon Monitor was approved for the New Horizons mission, currently on
its way to Pluto, beaming back a simple beacon as it goes.

Discover more about Beacon Monitor technology, as well as other
technologies, on the NMP Technology Validation Reports page,
[http://nmp-techval-reports.jpl.nasa.gov](http://nmp-techval-reports.jpl.nasa.gov/).

This article was provided by the Jet Propulsion Laboratory, California
Institute of Technology, under a contract with the National Aeronautics
and Space Administration.

![](media/image1.jpeg){width="6.0in" height="2.0875in"}

Caption:

This artist\'s concept shows the New Horizons spacecraft during its
planned encounter with Pluto and its moon, Charon.  The spacecraft is
currently using the Beacon Monitor system on its way to Pluto.  *Credit:
Johns Hopkins University Applied Physics Laboratory/Southwest Research
Institute (JHUAPL/SwRI)*

*Note to editors:*

*This image may be downloaded from*
<http://spaceplace.nasa.gov/news_images/nh_panoramic_lg.jpg>