Day 3 STS-62

shuttle glow phenomena lights orbiter s tail.



experiments in columbia s payload bay

on flight day 3 (sunday, march 6), following morning of medical studies, crew spent last half of day exercising , continuing study behavior of space station truss model in weightlessness. pilot allen , mission specialists ivins , gemar each took turn on stationary bicycle mounted in columbia s middeck. stationary bike had long been staple of shuttle flights allow exercise countered effect of weightlessness on muscles. bike aboard columbia, however, featured new mounting system of shock-absorbing springs evaluated method of keeping vibrations exercise, disturb sensitive experiments, minimum.

also, gemar set model of scaffold-like truss structure applied future space station design in lower deck. model, linked sensitive recorders in shuttle locker, used determine characteristics of such structures in orbit. model , reactions studied in several different configurations during day.

other activities crew included photography of glow created orbiter s outer skin interacted atomic oxygen in orbit, , continued monitoring of protein crystal growth experiments in cabin.

although not highly visible except earth-bound scientists watching on them, columbia s wide assortment of external payloads continued investigations throughout day. second united states microgravity payload (usmp-2) experiments continued produce wealth of data scientists on ground.

the critical fluid light scattering experiment, or zeno, science team reported expected locate critical temperature of xenon @ time. team members closely watched computer data traces indicate experiment near critical temperature—the goal of lengthy, methodical sensitive search process. more precise search critical temperature after location had been determined within narrow band. once temperature located, team spent 24 hours taking @ phenomenon waited years see. studied properties of xenon @ critical point, taking subtle optical measurements in region surrounding it. fluid s critical point occurs @ condition of temperature , pressure fluid simultaneously gas , liquid. understanding how matter behaves @ critical point, scientists hope gain better insight variety of physics problems ranging phase changes in fluids changes in composition , magnetic properties of solids.

the space acceleration measurement system (sams) continued measure microgravity environment on usmp-2 carrier in support of 4 other experiments on board. sams team began sending results of data collection during various orbiter activities crew, interested in how minimize influence on microgravity environment. measurements made system @ specific times when microgravity disturbances caused events such crew exercise , movement of orbiter s ku-band antenna. such observations collected signatures team able identify in future data.

a related system, orbital acceleration research experiment (oare), managed nasa s johnson space center. useful on missions such usmp-2 important accurately characterize wide variety of disturbances in microgravity environment. working closely sams, oare recorded low-frequency activity such orbiter s friction rarefied upper atmosphere. sams suitable recording higher-frequency activity such crew exercise.

the isothermal dendritic growth experiment (idge) continued assemble data test theories concerning effect of gravity-driven fluid flows on dendritic solidification of molten materials. upon completion of first phase of pre-programmed operations previous night, dendritic experiment entered second phase of crystal growth when team members began sending commands experiment ground using unique set of capabilities known telescience. allowed them best possible data investigation.

the advanced automated directional solidification furnace (aadsf) studied directional solidification of semiconductor materials in microgravity. downlinked experiment data third day of mission indicated solidification of crystal of mercury cadmium telluride took place, , aadsf science team monitored slow steady progress. testing aadsf in microgravity beneficial because on earth, gravity causes fluids rise or fall within melted portion; warm liquid less dense cool 1 , rise top of melt. these convective movements of molten material contribute physical flaws in internal structure of growing crystal. such flaws affect crystal s overall electrical characteristics, , consequently, usefulness in electronic devices.

the mephisto team reported had gathered data directional solidification furnace. during day, team troubleshooted problem discovered on previous night troublesome seebeck measurement. electronic signal measured changes in microstructure of solidifying metal, , conducted on 1 of 3 experiment samples of bismuth-tin. other measurement techniques used on 2 remaining samples later in mission; both these samples operated nominally.

flight controllers had quiet sunday in mission control no significant troubles seen aboard spacecraft. reading of high pressure seen in fuel line 1 of shuttle s 3 auxiliary power units earlier in flight had dissipated, , controllers became confident apu operate if needed. however, continued closely watch readings area. crew began 8 hours of sleep @ 4:53 pm.