QUESTION:
How long did it take to build the Galileo Space Probe?

ANSWER from Dan Carlock, Jr. on January 2, 1995:
The Galileo Probe required approximately five years to build, even
though testing, redesign, and programmatic slips arguably stretched it to
seven years.

Design, development, integration and test of the Galileo Probe
commenced at Hughes Aircraft Company (now Hughes Space & Communications
Co.) shortly after contract award by NASA-Ames Research Center in September
1978.  A major perturbation to the program was introduced in 1979 when Ames
directed that the Probe be redesigned to tolerate single-point electrical
faults, by the incorporation of "dual-strings" (i.e., two independent
command and communications channels, and redundancy in power distribution).
This resulted in major redesign of the Descent Module, which was derived
from the "single-string"  Pioneer Venus large probe previously built by
Hughes.  Also, multiple launch postponements and subsequent adoption of the
"VEEGA" Venus and Earth-Earth gravitational assist trajectory required
additional effort in terms of a shelf life study and refurbishment of
selected subsystems such as the battery modules, parachutes, and mortar
assembly pressure cartridge.

In early 1983 the Probe had completed initial assembly; during the
remainder of that year environmental testing was conducted.  In 1984,
extensive system-level testing consumed most of the year; and several
months of system testing with the Orbiter were required at JPL in 1984 and
1985 before final delivery occurred.  Throughout the system test phase, the
design of the Probe was repeatedly iterated and improved.  By late 1985 the
final buildup of the Probe was completed.  The Probe was shipped to JPL in
early December 1985-- seven years after work was initiated.  Following the
Challenger disaster in 1986 and subsequent launch postponement, the Probe
underwent an extended period of disassembly, storage, refurbishment and
reassembly, then final testing before redelivery to JPL in early 1989.


ANSWER from Charlie Sobeck on January 6, 1996

It took many years to build the Galileo spacecraft.  For the probe which
went into the atmosphere, after several years of thinking about the
problem, it took about two years to design the probe, another two years to
build all the pieces and then another two years to put it together and
test it to be sure it would work.  All this work was finished in about
1984.  Since then we have been making improvements, doing more testing and
flying to Jupiter. 


ANSWER from Dr. Karen Buxbaum on January 4, 1996:
You asked a straight-forward question, but I'll tell you up front that I 
can't give you a straight-forward answer!  I had to do some homework to 
get the facts.  Here's how I went about the fact-finding and next is a 
summary of what I found.

First I checked a book I have about the Galileo Mission.  There is an
interesting little section called history.  It reminded me that the
mission was approved by Congress in 1977 and work was supposed to start in
October, 1977.  The next important point was that the original launch date
was supposed to have been January, 1982.  The 1982 launch was delayed,
primarily due to some development delays in the Space Shuttle program
(Galileo was supposed to be the first spacecraft launched by the new
shuttle).  There were alternate launch dates after 1982, but the first
time the Galileo spacecraft was loaded onto a truck and shipped to the
Kennedy Space Center was late in 1985, in preparation for a May 1996
launch.  You were pretty young to remember January 1986, but something
happened that changed the Galileo Mission schedule:  the Space Shuttle
called Challenger blew up just after launch and all future shuttle
launches were postponed; the Galileo launch was again put on hold. 

Our spacecraft was trucked back to JPL in California.  While it was here, 
waiting for its next launch date assignment, some more changes to the 
spacecraft were made.  Finally, in 1989, Galileo was trucked back to 
Florida and then launched in October, 1989.  So those are the facts.  
Now here's how I can use those facts to answer your question.

1. The original plan was to build the Galileo spacecraft in about 4 
   years, move it to Kennedy Space Center (KSC), and launch it.

2. As the schedule changed, the engineers took advantage of the delay and 
   used more time to build the spacecraft.

3. If you count the time from mission start in late 1977 to the first 
   time the spacecraft was shipped to KSC in late 1985, it was 8 years.
   So, one answer could be:  8 years.

4. But then if you count the time from mission start in late 1977 to the 
   second (and last) time the spacecraft was shipped to KSC in early 
   1989, it was just over 10 years.  So, another answer could be:  10
   years.

So, there!  Sometimes you just can't squeeze a simple answer out of a
simple question.  But it was a good question, and I learned a lot working
on figuring out a good answer.  I hope you learned some interesting
things, too.