[meteorite-list] Communications Established with ISEE-3 Spacecraft

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 29 May 2014 15:09:05 -0700 (PDT)
Message-ID: <201405292209.s4TM959J003480_at_zagami.jpl.nasa.gov>

http://spectrum.ieee.org/tech-talk/aerospace/satellites/isee3-update

Space Hackers Take Control of ISEE-3 Spacecraft
By Rachel Courtland
IEEE Spectrum
29 May 2014

After a few days of waiting for transmission approval from NASA and an
earthquake that shook the Arecibo Observatory in Puerto Rico on Wednesday,
a private team of space enthusiasts has established two-way communication
with the 35-year-old ISEE-3 spacecraft. The probe is now sending back
telemetry, team member Keith Cowing says. Over the coming days, the team
will analyze the data ISEE-3 is transmitting in order to assess the health
of the spacecraft and see if they will be able to fire its thrusters,
beginning a process that could bring the spacecraft back to its original
orbit near the Earth.

The ISEE-3 reboot team, which raised nearly $160,000 on RocketHub to fund
the effort, has been racing to cobble together what they need to communicate
with ISEE-3, including transmitters as well as software-defined modulators
and demodulators. Everything was in place by last Friday, the team reported,
but they had to await clearance from NASA. That put some pressure on the
team's already tight schedule: they expect they have until mid-June to
command the spacecraft to fire its thrusters for the first time.

I called NASA on Wednesday to ask about the source of the delay. NASA
signed an agreement last week that handed over control of the spacecraft
to the team, which is led by the California-based firm Skycorp. But that
agreement still requires NASA to approve certain steps.

In this case, the main source of the hold-up was getting authorization
from the U.S. National Telecommunications and Information Administration
to send signals to the spacecraft from Arecibo using the team's 400W transmitter.

"Because NASA still owns the spacecraft, NASA actually has to apply for
the license on behalf of Skycorp," David Chenette, the director of the
heliophysics division within NASA's Science Mission Directorate, told
me. One concern, he says, is damage to other spacecraft. "The power levels
are high enough to damage receivers that operate on this frequency should
they be going through the beam," Chenette said. That list of potentially
vulnerable probes includes NASA's Lunar Reconnaissance Orbiter and Earth
Observing-1, JAXA's WINDS spacecraft, and ESA's Cluster and Swarm spacecraft.

Because of this issue, the team only has clearance to transmit to the
spacecraft until May 31, Skycorp's CEO Dennis Wingo wrote to me over Skype
from Puerto Rico, shortly before today's attempt at communication. "After
that we have to say 'mother may I' again," he wrote, adding that going
forward his team hopes to automate the communications process so that
transmission will not occur if any spacecraft that might be affected are
in the area.

In the meantime, the team will be working out how to interpret the data
that ISEE-3 is now sending back to Earth. "We will use that data to debug
the demodulator software, then we get bits out, then we process for telemetry,"
Wingo wrote. He hopes that by early next week they'll have some initial
idea of how well the spacecraft's systems are faring.
Received on Thu 29 May 2014 06:09:05 PM PDT