Late Breaking News

NICMOS Recovery September 21, 2009

NCS cooldown - Instrument operational - SMOV proceeding

As of September 20, 2009, the recovery of NICMOS has passed a
significant milestone with the successful completion of the
filter wheel mechanism test, for all 3 cameras. This marks the
transition from the operational health and safety recovery
to the more nominal SMOV program that will now proceed.

The NCS crycooler system has been performing well since its
successful restart in August, when both the circulator and
the turboalternator were restarted at a set of thermal
conditions that were chosen to mitigate the risk of further
interference by ice contaminants in the system. The cooldown
proceeded smoothly to the nominal NCS setpoint of 72.4 K,
which it was able to maintain while the NICMOS instrument
remained in SAFE mode. After the NICMOS electronics were
enabled, which placed additional heat into the system, the
setpoint had to be raised to 75 K in order to allow a stable
temperature to be maintained.

The NICMOS detector electronics successfully passed their
initial check (the DC transfer test) on September 15, 2009
enabling the instrument to be transitioned to its operational
state. With the subsequent verification of the focus mechanisms
and filter wheel operation, NICMOS is now able to continue
with the rest of the nominal SMOV programs through October.
Some further tests will be carried out to determine the best
temperature setpoint for the final stable operational state
of the instrument. Given the new thermal configuration post-SM4,
NICMOS will likely be operated a few degrees warmer than pre-SM4;
initial indications are that this can be calibrated as before.

For subsequent information about the instrument characteristics
and progress of the SMOV program, please consult the NICMOS
webpages: http://www.stsci.edu/hst/nicmos

NICMOS / NCS Status July 30, 2009

New attempts are being made to restart the NICMOS Cooling System (NCS), following the recommendations
of the Anomaly Review Board (ARB) that was convened after the previous restart attempts and safing
in January 2009. An initial attempt within the past week was successful at restarting the circulator
loop, as well as the turboalternator at its initial speed setting, but resulted in a safing after the
turboalternator was ramped to its operational speed setting. After further discussions, another
attempt will be made in the near future using a slightly different set of startup conditions, aimed at
reproducing aspects of previous successful restart attempts. Please continue to check this page for
further updates.

New NICMOS ISRs available

The NICMOS team has published the following Instrument Science Reports:

NICMOS ISR 2009-001 (E. A. Barker & T. Dahlen):
"New Bad Pixel Mask Reference Files for the Post-NCS Era"
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_001.pdf.

NICMOS ISR 2009-002 (T. Dahlen et al.):
"Temperature Dependent Dark Reference Files: Linear Dark
and Amplifier Glow Components"
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_002.pdf.

NICMOS ISR 2009-003 (T. Dahlen, M. Sosey & E. Bergeron):
"Updates to Calnica: Using Temperature Dependent Reference Files"
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_003.pdf.

NICMOS ISR 2009-004 (A. C. Viana, R. S. de Jong & A. M. Koekemoer):
"NICMOS Photometric Calibration Pipeline"
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_004.pdf.

NICMOS ISR 2009-005 (D. Thatte & T. Dahlen):
"NICMOS Temperature Dependent Flat-fields"
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_005.pdf.

NICMOS ISR 2009-006 (N. Pirzkal, R. Bohlin & D. Thatte):
"NICMOS Grism Wavelength Calibration"
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_006.pdf.

NICMOS ISR 2009-007 (N. Pirzkal, D. Grumm & E. Bergeron):
"CalTempFromBias:Implementation and Testing:
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_007.pdf.

NICMOS ISR 2009-008 (T. Wiklind & D. Thatte):
"NICMOS Breathing and Focus Field Variations"
http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2009_008.pdf.

NICMOS / NCS Status January 23, 2009

After the previous restart attempt and subsequent safing of
the NICMOS Cooling System (NCS) in December 2008, an Anomaly
Review Board was convened to examine the failure, which this
time was not due to the circulator pump but was instead
caused by a low speed limit violation of the Turbo
Alternator, which helps to maintain the proper flow rate of
coolant. After examination of the data, approval was given
by HST Project for a restart attempt on Thursday, 15 January
2009. The system initially restarted nominally, with the
circulator pump motor behaving as expected and soon reaching
a stable current level of around 62 mA, which it maintained
for the next 24 hours. On Friday 16 January 2009, approval
was given to proceed with the cooldown phase which involved
activating the compressor and Turbo Alternator, this time
with modified restart parameters. The cooldown proceeded for
about 10 hours until the Turbo Alternator safed, again with
a low speed limit violation similar to the signature seen in
December 2008. The HST Project has decided to defer
subsequent NICMOS Cooling System startup attempts until
after Servicing Mission 4, due to limitations on the amount
of time remaining.
At STScI, the HST Mission Office and the Director's Office
were involved in these discussions and support this decision.
The NCS Anomaly Review Board is continuing its investigation
of the failed restart attempts and will prepare a recommended
plan of action for any future restart attempts after SM4.