Day 191 in space for Peggy & Yuri.
Last day before Soyuz 15S undocking, with the ISS crew on an irregular wake/sleep cycle:
Sleep: 1:00am - 12:30pm EDT;
Wake-up: 12:30pm - 4:45am (4/19); E16 departs @ 1:06am
Sleep time for E17: 4:45am - 2:00am (4/20)
The E16/E17 crew rotation/handover period is running down. Whitson, Volkov, Malenchenko and Kononenko are completing their joined crewtime for dedicated ("functional") CDR/CDR & FE/FE handover activities plus "generic" handovers where crewmembers are scheduled together to complete various designated standard tasks.
From the US voluntary "job jar" task list, after wakeup and before breakfast, FE-2 Reisman & SFP (Space Flight Participant) So-Yeon Yi again downloaded the SLEEP (Sleep-Wake Actigraphy & Light Exposure during Spaceflight) experiment data from their Actiwatches to the HRF-1 (Human Research Facility 1) laptop. Yi has been participating in SLEEP for NASA under a Space Act agreement with South Korea. Later tonight, CDR Whitson will work with her own, Garrett's and So-Yeon's Actiwatch, downloading their accumulated data to the HRF-1 laptop, initializing her unit for FE-2 Reisman, then stowing the SLEEP hardware and powering down the HRF1 laptop. (To monitor the crewmember's sleep/wake patterns and light exposure, crewmembers wear a special Actiwatch device which measures the light levels encountered by them as well as their patterns of sleep and activity throughout the Expedition. The log entries are done within 15 minutes of final awakening for seven consecutive days.)
For Peggy & Garrett, the second session with the biomed experiment INTEGRATED IMMUNE (Validating Procedures for Monitoring Crew member Immune Function) ended today with the CDR & FE-2 performing their final INTEGRATED IMMUNE blood and liquid saliva collection, assisting each other with the blood draw, photo-documented by Kononenko. The subjects' saliva return pouches and blood sleeves as well as the saliva collection kit were then stowed in the MELFI (Minus-Eighty Laboratory Freezer for ISS), which Reisman had prepared with ICEPACs before. (IMMUNE assessment, integrated with the Russian IMMUNO, is a 24-hr. test of human immune system changes, with the objective to investigate immune neuro-endocrine reactions in the space environment by studying samples of saliva, blood and urine before, during and after flight for changes related to functions like bone metabolism, oxidative damage and immune function, using collection kits and the biomedical (MBI) protection kit, to develop and validate an immune monitoring strategy consistent with operational flight requirements and constraints. The strategy uses both long and short duration crewmembers as study subjects. The saliva is collected in two forms, dry and liquid. The dry samples are collected at intervals during the collection day using a specialized book that contains filter paper. The liquid saliva collections require that the crewmember soak a piece of cotton inside their mouth and place it in a salivette bag; there are four of the liquid collections during docked operations. For cold storage, samples are secured in the MELFI. Also included are entries in a fluid/medications intact log, and a stress-test questionnaire to be filled out by the subject at begin and end. Urine is collected during a 24-hour period, conventionally divided into two twelve-hour phases: morning-evening and evening-morning.)
FE-1 Malenchenko, with assistance by CDR-17 Volkov, prepared for his return to Earth by spending about two hours in the Soyuz with packing and stowing of equipment, after transferring BTKh-1,-2, & -4 (Glycoproteid, MIMETIK-K & VAKTsINA-K) sample hardware in the "Luch-2" kit, the "Konyugatsiya" (BTKh-10, Conjugation) experiment in the Recomb-T kit from CRYOGEM-03M, and INTERLEUKIN-K (BTKh-20) to TMA-11.
Also transferred for return were the Russian payload TkhN-9 SVS (Self-Propagating High-Temperature Synthesis) equipment, the Japanese GCF-JAXA Crystallization Facility, the Russian SAMPLE experiment, and other payload items, with transfers logged in the IMS (Inventory Management System).
SFP So-Yeon Yi meanwhile closed out and transferred her experiments KAP01 (Growth & mutation of plant seeds) and KAP03 (Development of Bioreactor for use on the ISS).
FE-2 Reisman set up, programmed and verified the IWIS (Internal Wireless Instrumentation System) with its RSUs (Remote Sensor Units) and NCU (Network Control Unit) to record structural dynamics/vibrational data during the ISS free drift and Soyuz undocking periods. The departure will also be recorded by the external SDMS (Structural Dynamics Measurement System).
Garrett conducted the routine maintenance of the SOZh system (Environment Control & Life Support System, ECLSS) in the SM, including ASU toilet facilities systems/replaceables.
Oleg Kononenko completed the daily IMS (Inventory Management System) maintenance, updating/editing its standard "delta file" including stowage locations, for the regular weekly automated export/import to its three databases on the ground (Houston, Moscow, Baikonur).
The remaining crewmembers completed their regular 2.5-hr. physical workout program (about half of which is used for setup & post-exercise personal hygiene) on the CEVIS cycle ergometer (FE-2), TVIS treadmill (CDR-17, FE-17), and RED resistive exercise device (FE-2).
Afterwards, Garrett & Oleg downloaded the crew's exercise data file to the MEC (Medical Equipment Computer) for downlink, as well as the daily wristband HRM (Heart Rate Monitor) data of the workouts on RED, followed by their erasure on the HRM storage medium (done six times a week).
As Whitson, Malenchenko and Yi prepare to ingress Soyuz TMA-11, CDR Volkov is scheduled (at ~8:55pm) to configure the onboard communications system (STTS) for the undocking, both working to set up, check and maintain the VHF comm link from the TMA-11 SA to TsUP/Moscow via RGS (Russian Ground Site) and the comm system for Soyuz undocking and descent.
Work hours for the crew continued into the next day (4/19) in support of the Soyuz undocking and post-undocking activities, with sleep time beginning at 4:45am EDT.
If everything is nominal, the return to Earth of the TMA-11 spacecraft tomorrow morning will proceed along the following approximate event sequence (all times EDT):
ISS attitude control handover to RS --- 9:40pm (4/18);
ISS in free drift for FGB hooks open --- 11:30pm (4/18);
ISS in free drift for undocking --- 1:02:30am (4/19)
Hooks Open command --- 1:03:30am; automatic undocking from SM on DO15;
Separation springs action (delta-V ~0.12 m/sec) --- 1:06:30pm;
Manual separation burn (15 sec, ~0.65 m/sec) --- 1:09:30am;
ISS attitude control handover to US --- 2:00am;
Deorbit Burn start (delta-V 115.2 m/sec) --- 3:40:42am;
Deorbit Burn complete --- 3:45:06am
Tri-Module separation (140.1 km) --- 4:04:37am;
Atmospheric entry (102.5 km, with ~170 m/sec) --- 4:07:30am;
Max G-load (32.7 km alt) --- 4:14:10am;
Parachute deploy command (10.6 km alt) --- 4:16:07am;
15S Landing (DO2) --- 4:31am EDT; 11:31am Moscow DMT; 2:31pm local Kazakhstan;
Local Sunset --- 9:36am (8:36pm local).
(Note: Kazakhstan time = GMT+6h; EDT+10h. Moscow DMT = EDT+7h.)
What the Soyuz TMA-11 crew will experience during their reentry/descent:
For the reentry, Malenchenko, Whitson and Yi will be wearing the Russian Kentavr anti-G suit. (The Kentavr garment is a protective anti-g suit ensemble to facilitate the return of a long-duration crewmember into the Earth gravity. Consisting of shorts, gaiters, underpants, jersey and socks, it acts as countermeasure for circulatory disturbance, prevents crewmember from overloading during descent and increases orthostatic tolerance during post-flight adaptation. Russian crewmembers are also advised to ingest fluid-electrolyte additives, viz., three sodium chloride tablets during breakfast and after the midday meal, each time with 300 ml of fluid, and two pills during the meal aboard Soyuz before deorbit.)
Special attention will be paid to the need for careful donning of the medical belt with sensors and securing tight contact between sensors and body.
During preparation for descent, before atmosphere reentry, crewmembers settle down comfortably in the Kazbek couches, fasten the belts, securing tight contact between body and the seat liner in the couch.
Dust particles starting to sink in the Descent Module (SA) cabin is the first indication of atmosphere reentry and beginning of G-load effect. From that time on, special attention is required as the loads increase rapidly.
Under G-load effect during atmosphere reentry the crew expects the following experience:
Sensation of G-load pressure on the body, burden in the body, labored breathing and speech. These are normal sensations, and the advice is to "take them coolly". In case of the feeling of a lump in the throat, this is no cause to "be nervous". This is frequent and should not be fought. Best is to "try not to swallow and talk at this moment". Crew should check vision and, if any disturbances occur, create additional tension of abdominal pressure and leg muscles (strain abdomen by pulling in), in addition to the Kentavr anti-G suit.
During deployment of pilot parachute (0.62 & 4.5 square meters), drogue chute (16 sq.m.) and main (518 sq.m.) chutes the impact accelerations will be perceived as a "strong snatch". No reason to become concerned about this but one should be prepared that during the parachutes deployment and change ("rehook") of prime parachute to symmetrical suspension, swinging and spinning motion of the SA occurs, which involves vestibular (middle ear) irritations.
It is important to tighten restrain system to fasten pelvis and pectoral arch.
Vestibular irritation can occur in the form of different referred sensations such as vertigo, hyperhidrosis, postural illusions, general discomfort and nausea. To prevent vestibular irritation the crew should "limit head movement and eyes movement", as well as fix their sight on motionless objects.
Just before the landing (softened by six small rocket engines behind the heat shield):
Crew will be prepared for the vehicle impact with the ground, with their bodies fixed along the surface of the seat liner in advance. "Special attention should be paid to arm fixation to avoid the elbow and hand squat" (instruction). Landing speed: ~9.9 m/sec.
Crew should not get up quickly from their seats to leave the SA. They were advised to stay in the couch for several minutes and only then stand up. In doing that, they should limit head and eyes movement and avoid excessive motions, proceeding slowly. They and their body should not take up earth gravity in the upright position too quickly.