STS-77 Mission Control Center 
Status Report #20 
 
Tuesday, May 28, 1996 -- 5 p.m. CDT 
 
Endeavour's crew Tuesday spent its final full day in orbit preparing
for a Wednesday morning return to Earth.
 
The astronauts performed a routine check of the shuttle's flight
control surfaces and reaction control system jets, wrapped up work
with a number of scientific investigations, and began securing the
cabin for the trip back to Earth.  Most experiments aboard the shuttle
have been completed and stowed away, although a few will operate
throughout the night and be deactivated once the crew wakes.
 
Crew members Andy Thomas, a native of Australia, and Marc Garneau, a
Canadian, each received special greetings today as STS-77 neared its
end. South Australia Premier Dean Brown called Thomas with
congratulations early this morning as the shuttle passed above Brown's
office in Adelaide, Australia, Thomas' hometown. Later, Canadian Prime
Minister Jean Chretien called Garneau to congratulate him on the
mission and the joint Canadian Space Agency and NASA experiments that
were conducted.
 
The crew will awaken at 9:30 p.m. and prepare for a Wednesday morning
return to the Kennedy Space Center. Weather conditions in Florida are
expected to be acceptable for landing, with only a possibility of
rain. If weather precludes a landing in Florida, flight controllers
have the option of returning Endeavour to Edwards Air Force Base in
California.  The Edwards site is available to support a Wednesday
landing, if required.
 
There are a total of four landing opportunities for Endeavour on
Wednesday -- two to KSC and two to Edwards Air Force Base.  The first
landing opportunity would call for firing Endeavour's braking rockets
at 5:09 a.m. Central time, with a landing at 6:09 a.m.  on KSC Runway
33.  The second KSC opportunity has a deorbit engine firing at 6:43
a.m.  Central time, followed by a landing at 7:44 a.m.
 
There are also two opportunities for Endeavour to land in California,
where the weather is expected to be acceptable to support landing.
The first opportunity calls for the deorbit burn conducted at 6:35
a.m. Central time with a landing at 7:36 a.m. on Runway 22.  The
second opportunity would have a deorbit burn at 8:10 a.m. Central time
with landing to follow at 9:11 a.m.
 
As Endeavour returns to Earth, it will conclude a voyage of 4.1
million miles, having performed a record four rendezvous during its 10
days on orbit. Endeavour rendezvoused with and retrieved the Spartan
207 satellite, and visited the PAMS-STU satellite three times,
spending a total of 21 hours of precise formation flying.