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(meteorobs) NEO News (2/4/00) NEAR nears Eros
------- Forwarded Message
Date: Fri, 4 Feb 2000 09:04:33 -0800
To: david.morrison@arc.nasadot gov
From: David Morrison <dmorrison@arc.nasadot gov>
Subject: NEO News (2/4/00) Near nears Eros
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NEO News (2/4/00) Near nears Eros
Dear friends and students of NEOs:
The Near Earth Asteroid Rendezvous (NEAR) spacecraft is approaching
its prime target, and if all continues to go well it will begin a
year-long orbital study of Eros on February 14. Following are two
recent bulletins on NEAR activities. I will send out only a few
highlights of this exploration saga on NEO News; those who wish to
follow on a daily basis are referred to the NEAR website at
http://near.jhuapldot edu/.
David Morrison
==============================================
NEAR Rendezvous Burn Delayed
February 2, 2000
The NEAR spacecraft went into a "safe" hold this morning
while preparing for today's scheduled rendezvous burn.
The NEAR team will attempt the maneuver tomorrow and the
mission remains on schedule for the Valentine's Day
encounter with asteroid Eros.
The rendezvous burn is a braking maneuver designed to
slow NEAR's speed relative to Eros (from 45 mph to 21
mph) and refine its trajectory toward the asteroid. The
spacecraft's onboard computer initiated the safe mode at
5 a.m. EST during a routine procedure that precedes a
change in NEAR's velocity. Mission operators stayed in
constant touch with NEAR and the spacecraft appears
healthy, though the NEAR team is looking into potential
causes of the problem.
- --------------------------------------------
Rescheduled Rendezvous Burn to Keep NEAR on Course
February 3, 2000
Mission operators sent commands to NEAR last night for a
revised engine burn that will keep the spacecraft on
course for asteroid Eros. Set for noon (EST) today, the
burn will cut NEAR's approach speed from 43 mph to 18
mph (relative to Eros) and refine its trajectory toward
the giant space rock.
A rendezvous burn scheduled for yesterday was canceled
when NEAR went into a "safe" hold soon after turning on
its accelerometers for the maneuver. During safe mode,
NEAR's onboard computers halt operations and await
instructions from Earth.
The NEAR team continues to study the anomaly, but to
avoid a similar occurrence it has decided to leave the
accelerometers on until after orbit insertion on Feb.
14.
- --------------------------------------------
NEAR Rendezvous Burn a Success
February 3, 2000
Preliminary indications show the NEAR spacecraft is on a
steady path to Eros, after a braking maneuver today
adjusted its approach speed and trajectory toward the
large asteroid.
At noon EST, NEAR's medium-sized thrusters fired for 90
seconds and eased the spacecraft from 43 mph (relative
to Eros) to 18 mph. The maneuver also moves NEAR's
trajectory about six-tenths of a mile (100 kilometers)
closer to its target.
The operation was a slightly modified version of the
rendezvous burn scheduled for Feb. 2, which was canceled
after NEAR went into "safe" hold early yesterday
morning. Mission operators at the Applied Physics
Laboratory sent new commands to NEAR late last night,
dividing the original Feb. 2 maneuver into two parts. A
second burn on Feb. 8 will bump NEAR's approach speed to
22 mph and put it back on its original track to the
asteroid.
"We were able to come back right away and devise a
turnaround burn," says NEAR Mission Director Bob
Farquhar. "It really shows the resiliency of the mission
plans."
All critical science operations - including a low-phase
flyby on Feb. 13 - remain on schedule. The flyby will
put NEAR directly between the sun and Eros, affording a
unique opportunity to map the asteroid's minerals under
optimal lighting.
NEAR is now 5,047 miles (8,123 kilometers) away from
Eros, which it will reach and begin orbiting on
Valentine's Day.
+++++++++++++++++++++++++++++++++++++++++++
David Morrison, NASA Ames Research Center
Tel 650 604 5094; Fax 650 604 1165
david.morrison@arc.nasadot gov or dmorrison@mail.arc.nasadot gov
website: http://space.arc.nasadot gov
website: http://astrobiology.arc.nasadot gov
website: http://impact.arc.nasadot gov
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