3 DROP TOWER
Contents
1. A 7 DOOD OOD 000000 OC OOO OO DUDUDI FRONT VIEW SIDE VIEW metres Figure 3 1 ZARM Drop Tower External View DROP TOWER page 3 2 Ss Yi European Users Guide to UIC ESA UM 0001 Low Gravity Platforms Issue 2 Revision 0 GA esa Upper end Upper end Access hatch Release Release mechanism mechanism Sled Sled Drop capsule Drop capsule Drop tube Lift Hall Deceleration unit Deceleration unit Compensator aa a ai AUN STOT III SITT STT Il S Deceleration container UUUODO DO desch a 1 EE d E ke GH bh Deceleration chamber i d WA Catapult Mounting construction Main building Catapult 0 10 20 A0 40 50 m men S metres Figure 3 2 ZARM drop tower interior layout DROP TOWER page 3 3 UIC ESA UM 0001 European Users Guide to esa Low Gravity Platforms EE IET tz Ee m B EE Se Physical Environment 3 2 1 Pressure Environment The drop capsule is a gas tight pressure vessel sealing the interior from the outer drop tube vacuum The interior is kept at atmospheric conditions throughout the whole procedure and the inner pressure is continuously monitored as part of the housekeeping data Pressure deviations may result from a temperature shift due to differences of ambient temperature between the integration area a2. hardware is used DC DC converters are recommended All power consuming items must be grounded to one identical point on each platform DROP TOWER page 3 12 a e S a European Users Guide to UIC ESA UM 0001 Low Gravity Platforms Issue 2 Revision 0 3 4 2 2 Electromagnetic Compatibility The electromagnetic emission levels of the experiment should be as low as possible It is in the user s own interest to reduce susceptibility and emissivity by following these simple design guidelines Avoid ground loops Separate alignment for power data and switch commands Twist and or shield emissive or susceptible lines Shield emissive or susceptible experiment components Avoid sparks and rapid electric charge transitions DOODO 3 4 3 Electronic Aspects of the Drop Capsule 3 4 3 1 Experiment Control Experiment control is enabled via the Capsule Control System CCS The engagement of the CCS into experiment control is mandatory The CCS operates like a storage programmable logic controller including data handling and the telemetry telecommand management The CCS offers virtual serial interfaces to enable embedding of user delivered electronic hardware In cases where the performance of the CCS is not appropriate e g in terms of sampling rate or resolution the user is requested to implement the needed hardware into his set up Triggering of the user hardware all mechanical or electronic elements is to be done by the CCS The timeline pr
3. onto a free flyer module which is mounted within the drop capsule The free flyer is released after the release of the drop capsule and is captured again just prior to deceleration 3 5 10 Combustion Research Laser Diagnostics The drop tower is equipped with a laser diagnostic system see Figure 3 11 for combustion experiments It enables users to perform PLIF diagnostics with a repetition rate of up to 250 f s during a drop It consists of Q A tuneable laser system attached to the upper end of the drop tube Q A mirror and a pointing system for the establishment of a stable light sheet in the capsule throughout the drop period Q An intensified digital high speed camera system 8bit conversion rate onboard the capsule Accurate synchronising of the camera gating with the laser pulses is done onboard of the capsule The laser delivers tuning in the 193nm 248nm and 353nm bands Within each band pulse to pulse switching of the excitation wavelength is possible by means of an oscillating grid attached to the tuning unit of the laser For more information users should visit the following web site http www zarm uni bremen de combustion html DROP TOWER page 3 16 European Users Guide to UIC ESA UM 0001 Low Gravity Platforms Issue 2 Revision 0 e IO D Q Laser Beam 28 x 28 mm IICCD Camera OA E AXXXXKXX Beam exit 45x45 mm gt Digital Recording etc CCS b Be TM TC radio module Power Sup
4. 0 Acceleration at Bremen Drop Tower Z axis Figure 3 4 Residual accelerations during the drop Image ZARM Spectrum of Residual Acceleration Bremen Drop Tower Weight of Capsule 500kg Ampl 10 qo IW 1 au ae 20 30 Freq Hz Figure 3 5 Fourier spectrum of accelerations after end of release transition Image ZARM DROP TOWER page 3 6 NM SS M K European Users Guide to UIC ESA UM 0001 esa Low Gravity Platforms Issue 2 Revision 0 Ee J a Ze M 3 2 3 3 Deceleration Forces The experimental hardware must be designed and mounted to withstand the deceleration forces encountered at the end of a drop Figure 3 6 is a typical deceleration curve of the ZARM drop tower As can be seen the deceleration lasts for about 0 2 seconds The average deceleration value is approximately 25 g and the peak value reaches about 50 g For design purposes these values must be considered as quasi steady accelerations The introduction of a safety factor of 2 is strongly recommended Therefore the experiment must be designed to withstand a deceleration of up to 100 g N B No damping elements are recommended shock absorbers might lead to an amplification of accelerations Therefore the best design is to fix all elements together and to the platforms as rigidly as possible Deceleration Forces at Bremen Drop Tower Z axis 541 time s Figure 3 6 Typical deceleration plot Image ZARM DROP TO
5. Figure 3 10 Experiment platform 3 4 2 Electrical Aspects of the Drop Capsule The experiment power supply can either be provided by the capsule s 28V rechargeable Experiment Battery or by the High Current External Power Supply see Available Facilities and Resources The onboard battery pack is of the lead gel type with a nominal capacity of 25 Ah The experiment is connected to the battery pack via the Experiment Power Control unit EPC 3 4 2 1 Experiment Power Control Unit EPC The EPC unit provides nominal 28V DC power to the experiment During the evacuation period the battery is buffered with a maximum of 10 Amperes by the Battery Load Power Supply which is disconnected about 90 seconds prior to the drop command Three output channels with up to 40 Amperes each can be switched via telecommand If power switching is required 3 Digital Out channels of the CCS are needed The channels are protected by slow 40 Ampere fuses This is only to protect the batteries against short circuits The protection of the user hardware with proper fusing is the responsibility of the user Experimental hardware connected directly to the power supply must have the following limitations Q Operational voltage range 26 4 V to 35 V DC OQ Maximum current per channel 40 Amps Q Electric strength 38V DC The actual voltage of the battery results from the initial charge status and the actual discharge as a function of time For cases in which input sensitive
6. Revision 0 H i 3 d TI vd 8 S O Stringer Platform SIV 1 7 NV 1 4 Base structure 0 02 04 06 08 1 Sen en rees metres Figure 3 8 Standard drop capsule Long version with and without pressurising cover DROP TOWER page 3 10 SE A A Ri European Users Guide to UIC ESA UM 0001 esa Low Gravity Platforms Issue 2 Revision 0 PAYLOAD AREA COMPUTER CCS BATTERY PACK SHORT CAPSULE LONG CAPSULE Figure 3 9 Dimensions of the Short and Long drop capsules 3 4 1 1 Experiment Platforms The experiment platforms see Figure 3 10 used to integrate experiments into the drop capsule are made of an aluminium plywood aluminium compound sandwich material These platforms can withstand the deceleration forces encountered in the ZARM drop tower and also provide rapid damping of release induced oscillations Experimental parts can be fixed safely on or underneath the platforms Users are also allowed to drill holes into the platform if large assemblies require this Users cannot construct platforms of their own and must use those provided by ZARM DROP TOWER page 3 11 We European Users Guide to UIC ESA UM 0001 E esa Low G ravity Platforms Issue 2 Revision 0 Diameter 700 mm Thickness 28 mm Hatched areas are platform holders underneath the platform in this area the platform can only be used on the upper side
7. WER page 3 7 W Ee M J EE CE SE amp European Users Guide to UIC ESA UM 0001 esa Low Gravity Platforms Issue 2 Revision 0 3 3 Scientific Research Suitable to the ZARM Drop Tower The following blocks Figure 3 7 highlight the various scientific fields which are suitable for research in the ZARM drop tower It is important to note however that these fields are based on the data from current and past research carried out at ZARM and should therefore NOT be considered exhaustive by the user Scientists should view the fields presented below as a guide and are encouraged to propose new research areas as long as their experiments can be executed within the limitations of the ZARM drop tower Le microgravity duration payload volume and mass costs available support equipment and diagnostics etc FUNDAM uN QO EE DES ction of dust and gas UI Thermophoresis FLUID AND COMBUSTION PHYSICS Combustion Droplet and spray combustion Soot concentration Combustion synthesis Laminar diffusion flames Flame vortex interaction m Fuel droplet evaporation MATERIALS SCIENCE Thermophysical properties Structure and dynamics of fluids amp multiphase Systems Pool boiling Multiphase flows Heat and mass transfer Dynamics of drops and bubbles Thermophysical properties Interfacial phenomena Isothermal capillary flows Extensional flows Dynamics and stability of fluids Liquid bridges Evaporation Ferrofluids Electromagneti
8. YoJeesel p pu u JO Uomdu2ser Saa EZ 7 SINOH Z 7 ZZ JESn 0 p J nj p WJose d yuswedxy S499M 0L 1 q 1949 IWNOILVYAdO YAMOL dOYA European Users Guide to Low Gravity Platforms H NNYI Jasn q Ajquiesse zu wn dxa Saa Z 7 9 OF 7 W014 L 0 S o sseoojd V D UOI JENDeAS JO pug Joo doJp ye ang SO NUIIN GL 7 gt Jasn a JUswWedxy A Le ste 01 7 um D 2 uoljsod youne M N Ajajes F O ul posed einsde5 Joyesado 0 uoljes6ejul JUeWIUedXy mies Jeaopuey jnsdeg skeq 1 7 2y s noH Z 1 Figure 3 13 Drop Tower utilisation operational cycle page 3 21 DROP TOWER a European Users Guide to UIC ESA UM 0001 e S a Low Gravity Platforms Issue 2 Revision 0 3 8 References Users can refer to the following documents and web addresses for further information regarding the ZARM drop tower and relative research 1 ZARM Internet Home Page http www zarm uni bremen de 2 ZARM Drop Tower Bremen User Manual Version 10 July 2003 Drop Tower Operation Service Company ZARM FABmbH Bremen 3 ZARM Drop Tower Bremen General Information Version 28 April 2000 Drop Tower Operation Service Company ZARM FABmbH Bremen 4 A world without gravity G S
9. arch text schemes drawings OQ The ZARM provided experiment platform s are shipped to the user s lab QO Preassembly of platforms is carried out by the users QO After the campaign has been scheduled the user is expected at the drop tower at least 10 working days before the first drop This time is needed for integration and ground testing QO The drop tower is operated with three drops per day not necessarily with the same experiment QO Each week has 4 operation days the Monday is reserved for system maintenance QO Each drop sequence which is defined as the period between handover of the capsule to the operator and then back to the user lasts 4 hours including safety margins The handover times are 8 a m 12 a m and 4 p m A handover delay of more than 30 minutes caused by the user will lead to cancellation of the drop from the schedule and will count as a performed drop Therefore users are encouraged to carefully monitor the preparation time required before scheduling a campaign QO After handover of the set up to the operator the capsule will be closed QO Experiments requiring a drop as opposed to the catapult are connected to the winding mechanism and lifted to the top of the tower During this process the user will not have access to the experiment for about 15 minutes QO After reaching the top end of the tower the telemetry telecommand line is checked and remote access is established The experiment is now connecte
10. between the platforms and the base structure along the stringers At the beginning of the mechanical design of a drop tower experiment the following technical data and limitations must be kept in mind The overall weight of a platform including the platform itself may not exceed 100 kg The point load of a platform at the centre may not exceed 50 kg The distribution of mass should be even The distance between the lower end of the stringers and the underside of the lowest experiment platform may not be less than 420 mm Ensure that all platform holders of one platform are exactly on the same level The overall height of the experiment may not exceed 980 mm short capsule or 1730 mm long capsule See Figure 3 9 O The maximum overall mass of the drop capsule is 500 kg Maximum payload mass short capsule 274 kg Maximum payload mass long capsule 234 kg DODO Oo Table 3 3 Masses and dimensions of drop capsule PARAMETER SHORT CAPSULE Stringer length mm 1545 2310 Mass of base structure including CCS and batteries kg 110 110 Mass of lid plate kg Mass of pressurising cover and connection elements kg Mass of 4 stringers kg Mass of nose cone with antenna kg Mass of 1 platform with connectors kg Net mass of capsule kg Maximum capsule gross mass kg Maximum payload mass kg DROP TOWER page 3 9 European Users Guide to UIC ESA UM 0001 Low Gravity Platforms rN IO o a Issue 2
11. cs Complex dynamic systems Thermomagnetics Surface forces and adhesion New materials products and processes Q Polymers Q Melt processing Q Metallic foams BIOLOGY Cell and developmental biolog Q Gravitaxis and gravikinesis LU UUUUUUUUOUUUUUUU Figure 3 7 Research fields carried out in the Drop Tower based on past experiments DROP TOWER page 3 8 SE 5 Yip My s wf J a Ye LE European Users Guide to UIC ESA UM 0001 eC S a Low Gravity Platforms Issue 2 Revision 0 3 4 Payload Accommodation 3 4 1 Mechanical Aspects of the Drop Capsule The user experiments are accommodated in a specially designed drop bus which is pressurised to atmospheric pressure and is shockproof to withstand the deceleration forces The base structure see Figure 3 8 and Figure 3 9 consists of the Capsule Control System CCS the electronic interface between experiment and experimenter the switchable power supply EPC Experiment Power Control unit and the radio telemetry telecommand system with parabolic microwave antenna mounted within the nosecone The different parts of an experiment are assembled on platforms shipped to the user s lab prior to a campaign for experiment pre assembly which are then successively connected to the four stringers of the rig two possible heights Finally the stringer rig is set onto the base structure and fixed Once at the drop tower all electrical and electronic connections are positioned
12. d r European Users Guide to UIC ESA UM 0001 E esa Low G ravity Platforms Issue 2 Revision 0 A DROP TOWER This section provides a guide to the ZARM Zentrum f r Angewandte Raumfahrt Microgravitation Drop Tower located in Bremen Germany which was officially declared an ESA External Facility on 2 October 2003 The section begins with a brief introduction to drop towers and drop tubes 3 1 Introduction 3 1 1 What Are Drop Tubes and Drop Towers Drop tubes and drop towers are ground based research facilities with which up to ten seconds of free fall weightless conditions can be achieved Drop tubes are dedicated to containerless processing for fundamental studies of material properties and solidification microstructures Samples usually liquid metal drops are released from the top of the drop tube and allowed to fall freely The aerodynamic drag which creates friction and subsequently convection in samples can be eliminated by operating the tube under vacuum thus creating weightless conditions Drop towers are multi purpose facilities which enable autonomous experiment packages to be submitted to true free fall conditions In most cases drop tower experiments are performed in an evacuated chamber to eliminate the effects of drag force Their high degree of flexibility permits investigations in different research areas A series of experiments can be conducted over a period of a few days enabling scientists to screen ranges and parame
13. d to all interfaces Q About 2 hours after handover to the operator the evacuation process will terminate having achieved a final pressure of lt 10 Pa within the drop tower The user now takes over operation and can drop the assembly whenever ready The user and operator work at the same desk and can discuss the procedure together QO During the drop all the data can be stored onboard otherwise it can be downloaded for evaluation after the drop via the telemetry line Q After the drop the tower is reflooded with air QO About 45 minutes later the capsule is retrieved opened and handed back to the user The user team will then do a final check of the hardware Q A single campaign is usually made up of 8 to 24 drops 1 to 3 weeks two drops a day This varies from experiment to experiment QO For anew experiment it is suggested to first carry out a shorter campaign review the experiment and then move on to a longer campaign This enables the user to optimise the hardware and thus the scientific output QO At the end of the campaign the user team and operator team dismantle the set up All parts developed at ZARM will be stored for a possible successive campaign The utilisation cycle is summarised graphically in Figure 3 13 DROP TOWER page 3 20 UIC ESA UM 0001 Issue 2 Revision 0 fj Jesn 0 yoeq pepuey juewiedxy t Duuecdo a jeAalJ es ajnsdeg SOUIUIW Sp 71 WHVZ
14. eibert et al ESA SP 1251 June 2001 5 Erasmus Experiment Archive EEA Internet address http www spaceflight esa int eea 6 Erasmus User Information Centre Internet Home Page http www spaceflight esa int users 7 Facilities for Microgravity Investigations in Physical Sciences supported by ESA ESA SP 1116 March 1995 DROP TOWER page 3 22
15. ge 3 1 t M J SS CE WE Its European Users Guide to UIC ESA UM 0001 eC S a Low Gravity Platforms Issue 2 Revision 0 p 3 1 4 Principal Characteristics of the ZARM Drop Tower The ZARM drop tower is a 146 m tall concrete shaft Figure 3 1 which provides near weightlessness up to 3 times a day for experiments dropped from the top of the tower 4 74 seconds of microgravity or catapulted upwards from below the tower 9 48 seconds respectively In September 2004 a catapult system was inaugurated at the ZARM drop tower Figure 3 2 which doubles the standard drop microgravity time and is located in a chamber 11 m below ground under the tower This catapult throws the capsule upwards from the bottom of the tower accelerating it by a pneumatic piston driven by the pressure difference between the vacuum inside the drop tube and the pressure inside the tanks The acceleration level is adjusted by means of a servo hydraulic braking system controlling the piston velocity This catapult system accelerates capsule masses from 300 kg up to 500 kg to a speed of 48 m s within 0 28 seconds The microgravity lab system itself is a cylindrical capsule with a diameter of 800 mm and a length of 1 6 m or 2 4 m depending on the space required Inserted platforms held in aluminium frames form the modular drop capsule structure After integration of an experiment prior to a drop or a launch the whole capsule is closed pressure tight with an alumi
16. means signals from the CCS to the experiment and in means signals from the experiment to the CCS Connection to the CCS is established via digital and analogue channels The digital channels are for experiment control and display the status of digital elements switches The analogue channels are for experiment and housekeeping data acquisition Analogue out channels can also be used for experiment control e g mass flow controllers 3 4 3 3 Virtual Serial Interface Two serial interfaces of the RS232 specification are available for the experiment The interfaces enable serial data transmission between experiment and external equipment at the ground station The transmission parameters can be adjusted at the ground station 3 4 4 Safety Requirements Even though the safety requirements for drop tower experimentation are minimal the user must examine the set up to identify potential hazards DROP TOWER page 3 13 a European Users Guide to UIC ESA UM 0001 e S a Low Gravity Platforms Issue 2 Revision 0 The major rules to be applied are summarised below O Gaseous fuels and oxidizers must be stored in different containers Ignitable premixture storage is prohibited There are no general pressure limits for gas reservoirs but pressurised reservoirs must be certified by the technical survey of the user s country In case this does not exist or the request is inappropriate the user must be able to handover the technical standards
17. meras are of the CCIR standard Only PAL standard VCRs are available Video standards used are videos or H18 3 5 4 Digital High speed CCD systems A digital non standard video recording system is available at ZARM 3 5 4 1 Camera Specifications DALSA CA D1 0256 A Area Scan Camera 256x256 pixel 1x8 Bit Digital RS422 Out A D Board L244 1x15MHz Data rate Maximum 225 Hz frame rate internal or external trigger Pixel size 16um square Frame Transfer Sensor LI UUUUUU 3 5 4 2 Recorder Specifications DigVid Housing H x W x D 180mm x 250mm x 450mm including space for connectors Mass 2 kg BIT Run PCI 24 digital interface board 32 Bit RS422 Input 30MHz BIT CONN RUN CAM2D Adaptor for a second camera with up to 16 Bit and differential interface Frame rate maximum 225 frames s with one or two synchronised cameras LU UUUUU DROP TOWER page 3 15 a European Users Guide to UIC ESA UM 0001 e S a Low Gravity Platforms Issue 2 Revision 0 QO Maximum recording time with two cameras and maximum frame rate 1 minute D Interface for external start stop Trigger and single image triggering Q Control software for parameter settings of grabbing and play function QO Power supply for two cameras and DigVid included Fra Pes Non standard Voltage Current supply The High Current Power Supply supplied by ZARM can be used as an external power supply providing 28V DC with up to 100 Ampere Switching of current is
18. nd the top of the tube In case of pressure increases due to outgassing of experiments or high power consumption values the pressure 1s released to the surroundings only during the evacuation process If the internal capsule pressure drops to less than 980 hPa the experiment procedure is stopped The drop is initiated when the tube pressure is below 10 Pa The actual values are monitored together with the other tower data in the control room Table 3 1 Drop tower environment pressure parameters PARAMETER 1 013 hPa 3 2 2 Thermal Environment The temperature of the interior of the capsule is continuously monitored and is in general maintained at room temperature RT In winter during the evacuation process the temperature can drop to 0 C Therefore for sensitive experiments the inside of the capsule can be heated up to RT Experiments can be connected to a thermal liquid circuit which is connected to a thermostat outside of the tube Through closed loop regulation the temperature can be adjusted to between 20 C and 60 C The circuit is disconnected about 90 seconds prior to the drop command An onboard heat exchanger with about 1 kW power can be made available Table 3 2 Technical data of the thermostat erature range DROP TOWER page 3 4 NM Ze M JP a CE WE M European Users Guide to UIC ESA UM 0001 eC S a Low Gravity Platforms Issue 2 Revision 0 3 2 3 Accelerations 3 2 3 1 Transition F
19. nium cover When performing a drop a winch pulls up the capsule to the maximum internal height of 120 m The specially designed release mechanism serves for low induction of disturbances during free fall The internal drop tube is evacuated before every drop or launch and the capsule is released catapulted at a residual pressure of 10 Pa The internal tube which has a volume of 1700 m stands detached at a height of 13 m on the 2 m thick roof of the deceleration chamber The detachment of the tube from the tower itself is necessary to assure quiescent conditions even during stormy weather During the free fall period of a drop or launch an ultimate microgravity quality with residual accelerations less than 10 g can be detected At the end of the experiment an 8 m high deceleration unit filled with polystyrene pellets decelerates the vehicle TOP VIEW
20. ogramme for automatic experiment control will be developed on site in close co operation with the user The specially developed software package SEPPEL Scientific Experiment Process control Programming Environment Language is easy to use and enables the implementation of conditional logical operations related to all in and out channels of the CCS This includes also the housekeeping data channels The SEPPEL Compiler then produces the operation software controlling all hardware elements The SEPPEL programme is a cyclic programme The time for one cycle which is the response time to changes of experiment conditions or interactive experimenter commands depends on the length of the programme and is typically below 10 milliseconds The number of user programmes running in parallel and independently is not limited The definition of common variables allow for synchronisation of the programmes After loading of the SEPPEL script into the CCS the telemetry telecommand line can be interrupted without affecting the programme operation Access to the CCS is password protected to prevent from unauthorised interference with the programme 3 4 3 2 Capsule Control System CCS After integration of the experiment into the mechanical structure the experiment becomes connected to the CCS The CCS is a modular system configured according to the experiment requirements The definition of out and in channels is from the CCS point of view Therefore out
21. performed with ramps This power supply is disconnected from the capsule about 90 seconds prior to the drop command 3 5 6 Vent Line Experiments releasing gases e g from cryogenic devices or combustion exhausts can be connected to a vent line The connector is located at the cover plate The gases can then be guided to the outside of the drop tube or released to the ambient vacuum To avoid thruster effects during free fall the vent line must be closed prior to release of the capsule During the free fall gases must be stored in onboard containers provided by the user Non contaminating cryogenic gases or combustion exhaust gases that are free from particulates e g soot PIV tracers can be released inside the capsule during free fall 3 5 7 Pressurised Air Reservoirs Pneumatic elements of an experiment can be powered via special stringers designed to serve as reservoirs for pressurised air This avoids using additional volume consuming reservoirs 3 5 8 Micro g Centrifuge Experiments that require data to be obtained during accelerations between Og and 1g can make use of a specially designed onboard micro g centrifuge The centrifuge consists of a rotating platform with adjustable rpm level equipped with a number of slip ring transducers for electrical power and signal transmission between the rotating platform and capsule KEN Free Flyer Experiments that require levels of residual accelerations less than 10 g can be installed
22. ply ly a Microwave antenna Figure 3 11 Laser diagnostic capsule Payload area limited to a height of 1300mm DROP TOWER page 3 17 a European Users Guide to UIC ESA UM 0001 e S a Low Gravity Platforms Issue 2 Revision 0 3 6 Payload Life Cycle and Major Milestones The payload life cycle varies from experiment to experiment and depends strongly on the complexity of the hardware as well as the channel through which access has been obtained to execute experiments in the ZARM drop tower Based on the data relative to campaigns carried out in the past the period that elapses from the moment in which the scientist contacts ZARM for the first time to the execution of the first drop varies between 4 weeks and 12 months But from an analysis of past experiments an average period of 6 months can be considered as a reference value Also experiments which are not being carried out for the first time will have a reduced integration time Figure 3 12 represents a typical timeline of an experiment aimed at providing users with an overview of the major milestones The user must keep in mind that although the tasks displayed in the timeline are standard the periods are based on a generic case and will differ as described above from experiment to experiment The timeline is given in terms of weeks with respect to the start of the tower drops L DROP TOWER page 3 18 SA UM 0001 C Issue 2 Revision 0 UI Eu
23. related to the design on request If hazardous gases are used an appropriate gas detector to monitor leakages must form part of the set up The release of toxic corrosive explosive or biohazardous contaminating matter into the capsule or to the outside of the capsule is prohibited The user is in any case requested to nominate potential hazards for the drop tower crew s safety Solenoid valves must be implemented into pressurised liquid circuits containing hazardous matter The use of mercury or unstable mercury containing mixtures is generally prohibited Batteries must be of the dry or gel type Liquid electrolytic batteries will be refused The centre of gravity of the set up shall be on the vertical axis of the capsule Change of motion of masses during free fall must be avoided If this cannot be achieved accelerations must be compensated for by accelerating counter weights on or around the identical axis Experiments that are mechanically weak and cannot be reinforced on site will be refused Every electrical element valves detectors etc subjected to hazards or hazard control must be connected to the CCS As any computer the CCS 1s not totally failsafe Therefore the experiment shall be in general designed as failsafe as possible OOoOvCOD LI LU D D O DROP TOWER page 3 14 a European Users Guide to UIC ESA UM 0001 e S a Low Gravity Platforms Issue 2 Revision 0 3 5 Available Facilities and Resources At the ZARM drop
24. rom 1g to 0g Users who wish to initiate their experiments before the drop begins should keep in mind that the transition from lg to Og might create disturbing effects for the experiment The release mechanism has been designed and revised over the years to achieve a relatively smooth transition but for some experiments it might still create relevant disturbances e g for levitation systems experiments with long relaxation times hardware like interferometers etc Figure 3 3 shows typical accelerations immediately after release of the capsule Acceleration during Release z axis 0 04 0 06 0 08 0 10 0 12 0 14 time s Figure 3 3 Typical accelerations immediately after release of capsule Image ZARM 3 2 3 2 Residual Accelerations The residual accelerations during the flight are generally as low as 10 g to 10 g Figure 3 4 depicts the residual accelerations during the drop of the experiment The data in Figure 3 4 and Figure 3 5 were recorded during a test drop of a capsule not containing an experiment The capsule was equipped with batteries a running Capsule Control System CCS data transmission system sensor platform and platforms loaded with screwed steel plates to provide an experimental equivalent mass The data presented is meant to provide the user with a reference data set DROP TOWER page 3 5 le S IO o A SE SS LE European Users Guide to Low Gravity Platforms UIC ESA UM 0001 Issue 2 Revision
25. ropean Users Guide to Low Gravity Platforms Jasn 0 13A0puey pue jesaja Usus Sdomp zuawnadxa a n39xX3 f Maia Ajayes Jo awoano uo paseq suopeaypow Aessasau no Aug j Ate 0 spsezey jenuazod Huipsebes Malha Ajayes i WaysAs 0 jU09 0 uopoauuog jnsdes doup out wiopejd zjuawnadxa yo uopg Bau i dn jas wuopejd zuawpadxa uym Wa Je aane Slaen i siasn Aq suwopejd oyuo dn jas zuawnadxa qe Joen 0 WYWZ Aq palaAljap suoyeld yuawadxy j yuawnadxa Jo juawdojanap pue uBisaq i Sa ab a ees Es a i Siaaufug Wale wo Woddns zuawdojarap pue UBisap dn jas jezuawnadxa Wie Aq sis jeue aBeyoed zuawnadxa WHVZ 0 eBeyded uonduasap zuawnadxa ywqns Wale 40 eBeyoed uonduasap juawnadxa aledaig j aouejdaace jesodoid o UOe YON f RON rees SS ee SR T r ft oY Fy TI IR UE EE E dE EE OI E CEET E IR E E E E Ff fT TT page 3 19 ign drop tower campai ina t Imen for an exper ine Typical timel Figure 3 12 DROP TOWER European Users Guide to UIC ESA UM 0001 e S a Low Gravity Platforms Issue 2 Revision 0 3 7 Utilisation Operational Cycle of the ZARM Drop Tower The following is a general outline of the main utilisation and operational events involved in a campaign at the ZARM drop tower QO Users prepare and submit a research proposal on the basis of the information provided in section 2 QO Once a proposal is accepted ZARM FAB mbH is contacted and given a description of the intended rese
26. ters Drop towers are very useful for obtaining quantitative data on physical phenomena with short characteristic times in the absence of gravity driven disturbances S12 What Do Drop Tubes and Drop Towers Offer Drop tubes and drop towers provide Facilities for experiments that require less than 10 seconds of weightless conditions Precursor opportunities for carrying out research in preparation for long duration missions Low cost access to research in weightless conditions A short experiment planning development execution cycle A fast turn around time The possibility of executing a series of experiments within a few days Direct intervention by research teams to make modifications between drops Minimal safety requirements A high quality low gravity environment lt 10 g A platform for new ideas in the field of microgravity research LI LI LI LI LI LI LI LI LI LI 3 1 3 Why Use Drop Tubes and Drop Towers The main reason for using drop tubes and drop towers is that they are extremely useful to students and scientists new to the field of microgravity research as well as to experienced researchers wishing to execute numerous short low cost tests before when foreseen moving on to costly long duration missions Even though the time of weightlessness to perform experiments is of the order of seconds the level of microgravity obtained is of extremely high quality providing good scientific data DROP TOWER pa
27. tower facilities and special equipment can be made available to the users upon request They include the following 3 5 1 Laboratories Workshops and Workplace ZARM has various laboratories and laboratory equipment that are placed at the disposal of the users The laboratories include a laser lab a bio lab a chemistry lab and a crystallography lab There are two major workshops Q A fine mechanics workshop with state of the art machinery that can be used by scientists to carry out changes repairs and adaptations to their hardware Q Anelectronics laboratory that is equipped to develop and build space proof hardware Any drop tower user will be provided with an integration area consisting of workbenches tools and Electronic Ground Support Equipment EGSE The EGSE allows users to perform ground experiments which follow the same procedures as in the tower under identical conditions except for weightlessness as often he she requires 3 5 2 Accommodation ZARM offers reasonably priced onsite accommodation in the form of an apartment The apartment is equipped with a shower phone satellite TV and a kitchen Alternatively ZARM FABmbH can make hotel guesthouse or vacation house bookings on behalf of users at special prices 3 5 3 CCD cameras VCRs Lenses Colour CCD cameras and appropriate lenses are available onsite The cameras are aimed at complementing the experimental hardware during integration or during the drop campaign The ca
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