markf%Nosc@usiiden.ARPA (08/06/85)
From: <crash!usiiden!markf@Nosc> Shuttle Spacelab Orbit News Conference 8/1During the last shift, we were wrapping up, what we callPDP POCCs operation, where we go out and actually flyaround the PDP. We flew around it twice, we got a lot ofscience data that we'll talk to you about later. We linedup the orbiter and the PDP on the magnetic lines of theEarth. The crew did an excellent job in doing that, thepropellant used was nominal, it was below 1 sigma, we camevery close to the place that we wanted to hit, and the crewcommented that they actually could see the electron gunwhen it was fired travelling up and hitting the PDP. Wewent back and picked it up, it is now parked out over thewing of the orbitter garthering more data. We picked upsome more science data using CCFD (crew control free drift)and I believe we're trying to point three differentfacillities all at the same time within a little bandwithout firing any jets. And we've worked up a program onthe ground that basically lets the orbitter take a look andsee where it was over the Ear t h, see what kind of forceswould be acting up on it, so that the crew could then takethose forces and start the orbitter in motion away, and asthe forces acted on the orbitter, then come back through ina dead band that was big enough to get all the targets thatthe science people wanted without actually firing the jets.And they got science readings for about 15 1/2 minuteswithout any jet firings and were able to get real goodobservations. With respect to IPS (instrument pointingunit) really all of it is tie d up in initial acquisitionand it deals with sun intensity and it also has a bearingon the fact that we take the star tracker and break thesun's image up into four different images, and reverse thepolarity, and we use that to focus the sun, so we need tokn ow the diameter of the sun, and make intensity typecomputations, and determine the offset pointing that weneed for the tracker. Since yesterday, we've taken a lookat more data, and as a matter of fact, we've loaded somecheckout software into the IPS, gath e red more data by theuse of that checkout software, and the guys at Marshallhave taken a look at that data, and they think that data isgood. We're in the process of developing a couple of morepatches in the IPS which is determining the atitudedetermination , so that we will have a better chance ofacquiring and the other is to change some more callibrationdata that is on-board. We will probably load this packagelater today. We're also looking at raising th e orbit somemore, that is in the work now. It probably wouldn't be fora day or so. ** As you may recall, after liftoff we lostthe computer redundancy. We have since not experienced anydifficulties (with the computer) whatsoever, and we havealternate means of compensating for any difficulty duringthe flight. We're quite pleased with the performance ofSpacelab so far, there's the fundamental system, thecomputers, all the mechanical systems, the thermocontrolsystems, have performed completely nominally, they ' veperformed just as expected. We have run into to only onemajor problem, that is the IPS in the fine pointing mode(note: the IPS has been repaired since this report waslogged). The IPS is working in an alternate mode which wasdesigned into the IPS. To use an experiment sensorsubstitute mode, that is we take a sensor that is rotatedand provided by the instrument, tie it into the IPS controlsystem, set it in a closed loop, and point in that fashion.This alternate mode of operation gives us good pointing and s tability. The problem that we have run into is isolated tothe optical sensor package, that is a sensor that looks atthe sun, the other two sensors are looking off to the sideacquiring stars. What we are seeing in the sun trackingmode, is it acquires nicel y, just as programs - down to therough tracking mode, it then starts toward isolating andcentering in on the sun, and its going towards the finetracking mode which gives the very fine pointing accuracy.Just as we get to the fine pointing part, just as wet r ansition from rough to fine, we see that an error existsout of the star tracker into a software filter that'slocated in the subsystem computer. It immediately recognizean error some what beyond its control authority, andimmediately kicks us back into the rough pointing. When weuse sensor substitution mode, we come right into finetracking, so we're continuing troubleshooting... We'retrying to trouble shoot this problem without impacting theuseful science being obtained in the sensor substitionmode. Now I'l l give a summary of the science of the lastday, we began to see real time television interviews fromthe high resolution telescope and spectograph instrument,being used in the sensor substitution mode on theinstrument pointing system. He's getting better th an twoarc seconds pointing stability in this mode... Secondinteresting thing was the spectacular fly around of theplasma diagnostics package and its recovery. And the jointobserving that was done during operations between theplasma diagnostics package and the vehicle charging andpotential experiment. The PDP has been recaptured and isnow in a standby mode taking data off to the side of theorbiter. Third was the first scientific operation of theinfared t elescope. The scanning of the sky with the Shuttlein the XDV (?) mode, with the shuttle essentially as anairplane with the payload bay directly away from the Earth.Experiment 8, the SOUP has not yet been turned on. TheCHASE experiment, continues to operat e very well. Exp 10,the High Resolution Telescope have continued to take gooddata of the hydrogen alpha that come down directly on thetelevision and can also be used by the crew and allow thecrew to point automatic systems. The crew control freedrift mode provides the best pointing stability, becausethere are no thruster firings to change the atitude duringthose operations. When we're on automatic thruster atitudecontrol, sometimes the bumbing of the vernier thrusterscauses the control to jump to a few mor e arc seconds, 4 to5 arc seconds, and so its clear the cruise control freedrift mode is a very good one for investigators. Experiment11 continues to take spectra. It still has a thermalproblem being evaluated in the hot orbit data facing theSun. HRTS did h ave a thermal problem, it seems to havecleared up. The Plasma Diagnostics Package, all theinstruments continue to operate very well. They havebeautiful display systems providing the data in colorvideo, in real time. The vehicle charging and potentialexper i ment has fired the electron generator a number oftimes, the crew has seen the beam being produced, and atone time saw it travelling out along the magnetic fieldlines of the Earth, which at that time was connecting theorbiter with the PDP. The Plasma Depl etion Experiment doesnot have any more engine firing schedules during thisimmediate period. Cosmic Ray Nuclei experiment had aproblem yesterday with its on board computer processor. Itwent down at a time when the count rate was very high, andthe radiation levels may have been a bit high and at thetime we were in the plasma diagnostic fly around mode, sothere was no way to get commands up to the cosmic raynuclei experiment to reconfigure it and turn it back on.That has since been accomplished, and the instr ument isback up and running. Infared telescope (exp 5) began togather data yesterday for the first time, all of theinstrument systems seem to be working very well. There areseveral wavelength bands in t he detection system, the highand low wavelength bands are operating very well. We aregoing to be able to map the sky in the 2 to 3 micrometerinfrared wavelength band and the 4.5 to 9.5 micrometerwavelength bands and gather maps of the sky that were notpos sible in the Infared Astronomical Satellite program.These wavelengths were not included on IRAS, so this willbe new infrared map data. The middle channels of theInfared telescope are seeing a very high, very brightbackground, and we're just now trying to u nderstand theorigin of that signal, we will be doing perhaps someadditional maneuvers of the orbitter and using differentscan directions, try to resolve the source. The heliumexperiment continues to operate very well. X-ray telescopecontinuing to gather s olid data. Looking primarily at thePerseus cluster of X-ray emitting gas and also had anopportunity to look at the crab nebulae which is acalibration source for them. Just looked at it briefly andfound that the intensities that their instruments saw weree s sentially exactly as they had anticipated, indicating thesensitivity of the instrument is right on design. They havea viewing camera which provides them with a reading ofexactly where they're pointed on the sky. The visual imageis put into their digital d ata stream and brought down tothe ground for processing. The camera has had a fewproblems, it turns itself off occassionally. It also hassome kind of contamination on its lens. Without thatcamera, they have a back up photo camera which can alsoprovide the data they need. But it is limited on the amountof real time analysis possible. But the accuracy of theirdata has not been impaired. The Vitamin D metaboliseexperiment continues. Samples have been taken and put inthe freezer and samples will be taken again at the end ofthe mission. Plant growth unit has been monitoredphotographically. The crystal growth experiment wasmonitored operationally.
rdp@teddy.UUCP (08/06/85)
In article <2968@mordor.UUCP> markf%Nosc@usiiden.ARPA writes: >From: <crash!usiiden!markf@Nosc> > Whoever is submitting these articles in this form: > >Shuttle Spacelab Orbit News Conference 8/1During the last shift, we were wrapping up, what we callPDP POCCs operation, where we go out and actually flyaround the PDP. We flew around it twice, we got a lot ofscience data that we'll talk to you abou