All ISS systems continue to function nominally, except as noted previously or below. Week 21 of Expedition 4 is underway.

Another day with off-duty time and crew rest after last week's hectic timelines.

Early in the morning (at 6:03-6:18 am EDT) the crew participated in a live interactive TV event on ABC's "Good Morning America", interviewed by Robin Roberts.

FE-1 Carl Walz performed planned maintenance on the U.S. CSA-CP (compound specific analyzer-combustion products), consisting of about one hour of unattended data collection and half an hour of logging (downloading) of the instrument's acquired data. [The CSA-CP is a toxicology monitoring device for early CO (carbon monoxide) detection/warning and post-fire decontamination. It also checks for HCl (hydrogen chloride) and other combustion products and contaminants. After today's task completion, there is one EXPRESS Rack 4 (ER4) CSA-CP deployed in the SM as prime and the other ER4 CSA-CP stowed near the kit. The maintenance is performed once every 30 days, restricted by battery life.]

CDR Yuri Onufrienko completed a periodic equipment operability check on the ESA-sponsored Global Timing System (GTS), using the Elektronika MMTs-01 multimeter to take voltage measurements on the antenna input diodes for determining their impedance (resistance).

Elektron oxygen generation system continues to be largely failed. MCC-Moscow is working on troubleshooting procedures. The primary pump in the newly installed Liquid Unit is not working, and the secondary pump, though running, shows degraded performance. Onufrienko switched the Elektron to operate on 16 Amps, the lowest setting. MCC-M will attempt to ramp its productivity up gradually, to 32 Amps. There is no oxygen remaining in the Progress 7P resupply ship, but large amounts (400 lbs) of gaseous O2 are stored in two HPGTs (high-pressure gas tanks) external to the U.S. Airlock (equivalent to 75 days for three crewmembers). In addition, the ISS has 160 SFOG (solid-fuel oxygen generator) "candles" (Russ.: TGK), of which three units per day would sustain three crewmembers. In the unlikely case of a protracted downtime of the Elektron, MCC-M and MCC-H both prefer use of the SFOGs over the Airlock supply, keeping the latter in reserve.

CDR Onufrienko worked on adjusting the IMS (inventory management system) database to reflect Soyuz TM-34 post-departure state. [Specifically, Moscow requested location information on items such as the KURS, removed from Soyuz, remaining VC (visiting crew) payloads, a Sony camcorder and the Italian ACT spectrometer and HALLEY kit. The glove box of the South African stem cell experiment ESCD (study of the development of embryo and stem cells in microgravity), with its biological material in a safe container, was approved for disposal in the Progress-257 (7P).]

FE-2 Dan Bursch continued his daily work on the BPS (biomass production system) test facility, today re-priming (filling) the BPS nutrient delivery system (NDS) reservoir, transfer pump and humidity control system (HCS) reservoir with water. If possible, he was to record the amount of air pulled from the reservoirs (if any). If he had the time, the BPS team wanted him to check for any seedlings in PGC1 (plant growth chamber #1), anticipated to emerge in the next couple days.

Bursch also completed daily maintenance of the CEVIS (cycle ergometer with vibration isolation and stabilization), a series of bungee system inspections performed once a month, followed by the monthly TVIS (treadmill) maintenance, which also focuses on the bungees used.

The daily routine systems support tasks of SOSH life support systems maintenance and Increment 4 payload status checks were completed by Dan Bursch, while Carl Walz performed routine maintenance on the RED (resistive exercise device) in the Node.

Later, at 2:24 pm EDT, Walz initiated the long-awaited and -discussed Metox (metal oxide) canister regeneration in the A/L. The process runs through tonight's crew sleep time and will be repeated tomorrow night on the second set of canisters. [The procedure was jointly approved with the operational constraint that the A/L remains off-limit to all crewmembers during the period between 2 and 4 hours into the regeneration due to elevated CO2 concentration in the air.]

POC (Payload Operations Center) has completed the ground testing of the BTR (biotechnology refrigerator) and plans to deactivate it from the ground once the "tub" has remained dry for several days. The crew was asked for their assessment of the condition of the tub during the daily payload status check, so that the ground can push forward with a plan for deactivation.

Yesterday, the ZCG (Zeolite crystal growth) payload showed anomalous temperature readings after emerging from LOS (loss-of-signal). With the crew's help, operators received a successful reboot indicating that both CPU's (central processing units) were operational. To prevent a second temperature cycle (heat-up) which could negatively impact science, the ZCG team decided to turn the heaters off and deactivate the unit one day earlier than scheduled, in order to troubleshoot the system before the next sample comes up on UF-2. The problem is that without a functioning MCOR (medium-rate communications recorder) it is hard to evaluate what went on with the ZCG during the LOS period.

MCC-M reports that battery #6 has failed in the Service Module (SM), leaving seven batteries functioning. The failure causes no power shortages for the Russian segment. Although there are no 800A storage battery spares on board, there are other 800A blocks in the FGB, and one from there can always be used in the SM in case of need.

The PLD1 MDM (payload computer #1) has failed after receiving a download command. This appears to be a known condition, and the procedure used for commanding the download is currently being studied for troubleshooting.

The GPS (global positioning system) navigation system continues to work well, but another glitch occurred yesterday when an attitude update by GPS2 was outside the limit range. GPS2 was voted "off the island" by majority vote of the set but came back in later when it performed a second update nominally. The three glitches to date are being investigated.

Starting this morning at 9:00 am EDT, MCC-H is running a two-day dual-angle test of the P6 BGA 4B (beta gimbal assembly 4B). The procedure was uplinked in a series of time-tagged (pre-set) commands for onboard storage and subsequent automated execution, with the ground only in observer position.

On 5/17 (Friday next week), ISS attitude will be steered back to XPOP, and the plan is to use the CMGs (control moment gyros) for this maneuver, for the first time. The objective is to find out whether CMGs indeed require less fuel for such maneuvers than the more traditional RCS (reaction control system) thrusters in the RS. As reported before, XPOP attitude is preferred by the U.S. side, for minimizing rotations required of the P6 BGAs. [However, as the ISS again goes through low solar Beta angles, XPOP would be conflict with a number of Russian obligatory experiments (three contracted, three international). To accommodate these requirements, the attitude will temporarily be moded to LVLH at those specific times, in the Beta range of +/- 30 degrees (i.e., 60 deg).]

Today's target areas for the CEO (crew earth observation) program were Mekong River Delta (wildfires in Cambodia and SW Vietnam were on the track, and the crew was asked to document point sources of smoke, if possible, and movement of smoke palls. With construction of dams beginning on the Mekong River, they were to record the state of deltaic wetlands prior to impoundment of river waters upstream. Detailed views of the wetlands west of Saigon are needed, as well as of any sediment plumes along the coast. ISS likely encountered clouds south of the coast), Lake Eyre (all of Lake Eyre was in view to the right of track. Lower light will favored photographing details of local accumulations of water in this ephemeral lake. In addition, crew was to look N along the western lakeshore and photograph hummocks that may support vegetation. Such hummocks mark "mound springs" where water reaches the surface along faults. The springs support a variety of flora and fauna not generally found in the hypersaline lake), Bombay, India (clear conditions in W. India probably permitted detailed photos of the megacity of Bombay, which was right of track), Arabian Sea Tropical Cyclone (as the ISS left the Mars-like landscape of the southern Arabian Peninsula, the crew was to look ahead and to the left over the Arabian Sea and photograph a tropical cyclone that is becoming increasingly organized. This is the first of this season. They were to record the spiraling bands and internal structures of the storm), Congo-Zimbabwe Biomass Burning (as the station traversed the lowlands north of the Zambezi River, the crew was to record both point sources of smoke and regional smoke palls, and to note water levels in Kariba and Cahora Basa reservoirs. The coastal plain of Mozambique has been uncommonly dry and photos are needed of the state of any vegetation there), Central American Fires (fires are still widespread in Yucatan, Honduras, and Nicaragua and smoke palls have been carried northward over the Gulf of Mexico, turning eastward over Florida. Of interest: recording smoke sources, where possible, and monitoring smoke transport to the left of track. ISS crossed the Isthmus of Panama along the Western edge of the Gulf of Panama; the Canal Zone was left of track. Weather should have permitted photographing the Canal Zone but probably deteriorated to the south).
CEO images can be viewed at the website http://eol.jsc.nasa.gov/

Environmental Control and Life Support (ECLSS) and Thermal Control (TCS):
Elektron O2 generator is On, using MNR backup pump (16 Amps). Vozdukh CO2 scrubber is ON in MANUAL cycle mode #5 (vacuum pump failed). U.S. CDRA CO2 scrubber is Off. BMP Harmful Impurities unit: Absorbent bed #1 in Purify mode, bed #2 in Purify mode.

SM Working Compartment: Pressure (mmHg) -- 756, temperature (deg C) -- 26.3, ppO2 (mmHg) -- 155.9, ppCO2 (mmHg) -- 2.5.

SM Transfer Compartment: Pressure (mmHg) -- 762, temperature (deg C) -- 19.6.

FGB Cabin: Pressure (mmHg) -- 756, temperature (deg C) -- 20.3.

Node: Pressure (mmHg) -- 748.98, temperature (deg C) -- 21.3 (shell); ppO2 (mmHg) -- n/a; ppCO2 (mmHg) -- n/a.

U.S. Lab: Pressure (mmHg) -- 751.38, temperature (deg C) -- 24.0, ppO2 (mmHg) -- n/a; ppCO2 (mmHg) -- n/a;

Joint Airlock (Equip. Lock): Pressure (mmHg) -- 751.28, temperature (deg C) -- 20.5; shell heater temp (deg C) -- 22.6, ppO2 (mmHg) -- n/a; ppCO2 (mmHg) -- n/a.

PMA-1: Shell heater temp (deg C) -- 23.0

PMA-2: Shell heater temp (deg C) -- 18.5

(Note: Partial pressures ppO2 and ppCO2 in U.S. segment [USOS] not available because MCA [major constituent analyzer] is failed and in Extended Life mode [= a state that preserves mass spectrometer vacuum but produces no pp data]). MSA (mass spectrometer assembly) and VGA (verification gas assembly) have been removed for return to Earth.

Electrical Power Systems (EPS):
Beta Gimbal Assembly (BGA) 2B in Autotrack mode, BGA 4B in Autotrack mode (dual-angle test in progress).
SM batteries: Battery #6 is offline (failed); battery #4 is in cycle mode; all other batteries (6) are in "partial charge" mode.
FGB: Battery #1 is offline (storage mode); all other batteries (5) are in "partial charge" mode.
Plasma Contactor Unit PCU-1 in Standby mode; PCU-2 in Standby mode.

Thermal Control Systems:
Air conditioner SKV-1 is On (repaired). SKV-2 is Off.

Command & Data Handling Systems:
C&C-3 MDM is prime, C&C-2 is back-up, and C&C-1 is in standby.
GNC-1 MDM is prime; GNC-2 is Backup.
LA-1, LA-2 and LA-3 MDMs are all operating.
PL-1 MDM is operational; PL-2 MDM on Standby.
APS-1 (automated payload switch #1) and APS-2 are both On.
SM Terminal Computer (TVM): 3 redundant lanes (of 3) operational.
SM Central Computer (TsVM): 2 redundant lanes (of 3) operational.

Communications Systems:
All Russian communications & tracking systems are nominal.
S-band is operating nominally.
Ku-band is operating nominally.
Audio subsystem operating nominally.
Video subsystem operating nominally.
MCOR (medium-rate communications outage recorder) is non-operational. Recovery to be attempted tomorrow (5/8).

Robotics:
SSRMS/Canadarm2 at Progress viewing position, with Keep Alive power on both strings.
RWS (robotics workstations) are Off.
Troubleshooting continues on SSRMS Prime string Wrist Roll (WR) joint.

ISS Orbit (as of this morning, 7:06 am EDT):
Mean altitude -- 390.4 km
Apogee -- 395.5 km
Perigee -- 385.3 km
Period -- 92.4 min.
Inclination (to Equator) -- 51.64 deg
Eccentricity -- 0.0007547
Orbits per 24-hr. day -- 15.59
Altitude decrease 300 m (mean) in last 24 hours
Solar Beta Angle: -13 deg (magnitude decreasing)
Revolutions since FGB/Zarya launch (Nov. '98) -- 19767
Current Flight Attitude -- LVLH (local vertical/local horizontal = "earth-fixed": z-axis in local vertical, x-axis in velocity vector [yaw: -10 deg, pitch: -7.25 deg., roll: 0 deg]).

For more on ISS orbit and naked-eye visibility dates/times, see
http://www.hq.nasa.gov/osf/station/viewing/issvis.html

Source: NASA