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Charles Redmond
Goddard Space Flight Center
Greenbelt, Md.                     Jan 1, 1993
(Phone:  301/286-8955)

DANTE ADVISORY #4

As of 8:35 pm January 1, the Dante robot was suspended about
21 feet below the crater rim at Mt. Erebus, Antarctica,
while the project team there reset the computers which
operate the robot's depth-perception and walking systems.

The robot had been successfully "launched" from its
stationary position at the top of the 750-foot deep crater
at about 2:00 am EST January 1 and had begun crawling down
the 40-degree incline towards the crater floor, suspended by
a critical support cable being reeled out by the robot
itself.

The computer reset was required because of activities which
had occurred the day before when both the Antarctic Erebus
"hut" computers and the remote computers located at the
Goddard Space Flight Center Dante payload control room were
both in communication with and controlling the robot.  This
"telerobotic" operation is one of the major objectives of
this joint NASA-National Science Foundation demonstration
project.

The Goddard computer connection was lost as a natural
consequence of losing the satellite connection through the
Tracking and Data Relay Satellite-West.  The satellite
communications between Antarctica and Goddard are scheduled
for pre-set periods each day.  The computer network connects
the Erebus computers and enables them all to function as a
distributed computing system.

In the Antarctic location there are several of these
computers, some of which are located in the operations hut
about 1.5 miles away from the volcano's rim, and one which
is located right on the rim.  When communications are
established between Antarctica and Goddard through the TDRS
satellite, the Goddard computers are added to the robot
network.

COMPUTER PROBLEM DESCRIBED AS COMMON

James Osborn, the Goddard-based Erebus project manager from
Carnegie-Mellon University's Robotics Institute, said this
type of computer problem is quite common in universities and
is easily fixed now that the team is aware of the problem.

Fixing this situation, Osborn said, is a simple matter of
resetting all the computers.  In the case of the one located
on the rim, Eric Hoffman, a member of the Carnegie-Mellon
team located at the Mt. Erebus site, would have to actually
go to the rim since the team believed their attempts to
reset the computers using software were not adequate.

Osborn said the Antarctic team was expecting to have this
problem fixed sometime between the last communications with
Goddard at 8:35 pm EST Jan. 1, and the first communications
session scheduled for Jan. 2 at 1:30 pm EST.  Dave Lavery,
the Erebus program manager also located in the Antarctic,
expected the team to have advanced the robot's position
several more hundred feet lower into the crater by early
afternoon on Saturday, Jan. 2, Eastern Time.

An earlier problem with the robot's tether reel mechanism
had delayed the launch of the robot yesterday and was
finally resolved when the Erebus team members decided to
physically modify the mechanism by removing a portion of the
winding system.

REEL MECHANISM WAS STICKING DUE TO COLD

The reel mechanism is very much like the reel on a fishing
rod and has a device which moves back and forth like a
bobbin to lay the reel smoothly onto the spool.  The
"bobbin" had been sticking because of the very cold
temperatures.  The Erebus team had sprayed lubricant on the
mechanism in several attempts to get it to operate smoothly,
but ultimately removed it completely.

Dave Lavery said this would present no problems to the
descent and bottom-of-the-crater exploration phases of this
project because the tether was properly tensioned and wound
smoothly.  It was only the rewinding of the tether onto the
reel which presented a possible problem.  Lavery said the
team understood the risk of this possibly inhibiting the
robot's safe return up the crater wall but was willing to
accept the risk to get the descent and exploration phase
underway.

The current schedule according to both Lavery and Osborn
calls for a two-and-a-half day descent and exploration phase
beginning at approximately 2:00 pm EST today and lasting
through Sunday, January 3.  During this period the robot
will descend down 70- to 90-degree slopes on the volcano's
inner rim wall and will traverse across about 150 feet of
crater floor to a molten lava lake.

PROJECT IS DEMONSTRATING NEW EXPLORATION CAPABILITIES

NASA and the National Science Foundation are undertaking
this demonstration project to develop technology and
telecommunications capabilities which NASA could use in
future explorations of the Moon or Mars and which the NSF
might apply to its ongoing research activities in the
Antarctic.  Part of the test involving the transfer of
control of the robot from the Mt. Erebus team to team
members located at a payload control center at Goddard was
successfully tested yesterday, Dec. 31 Eastern Time.

Carnegie-Mellon University and the New Mexico Institute of
Mining and Technology are partners with NASA and the NSF as
robotics and volcano experimenters for this project.
Carnegie-Mellon has four team members located on the
Antarctic ice and an additional five team members located at
the Goddard payload control center as part of this project.
New Mexico Institute of Mining and Technology has two
members associated with this project and two members
associated with an allied project on the ice for the Erebus
demonstration.
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