1. Common PDR Problems ACES Presentation T. Gregory Guzik March 6, 2003

2. Summary of Major Short Falls No plots or tables showing expected results Individual parts are not systems How do you select an appropriate sensor / ADC? No attempts to compute power requirements How to compute thermal requirements? Poor understanding of Development phase How to get data OUT of on-board storage? How do you test your payload? What is the WBS & how do you use it?

3. Section 3.0 Mission Objectives What is the difference between mission, science and technical goals? –Mission is everything from launch to results –Science is inquiry into nature –Technical includes the practical aspects What are your expected results? –From theory or previous measurements –Provides basis for instrument design –What sources are you measuring? –Needed for comparison with your data Generate Science Requirements –What needs to be measured with what accuracy and frequency

4. Section 4.0 Payload Design Principle of Operation –Show how your payload design will function to deliver the science requirements –How do your sensors work? –What is the expected accuracy of your measurements? –How will you cover the required range? A “Traceability Matrix” shows the logical flow from requirements to hardware

5. Section 4.0 Systems Individual parts are not systems “Spacecraft” has five major systems – Lift; Recovery; Payload; Beacon; Ground – Each of these has subsystems – Each subsystem has parts What are the systems in your payload? – Mechanical; Thermal; Power; Controller; Data Acquisition; Data Archive; Sensors; Ground – Each system has an interface to the other systems The remainder of Section 4.0 details each of these systems, their subsystems and parts

6. Section 4.0 Power All had difficulty figuring out what to do about power –The power budget is a list of the voltage, current and power (volts x current) required for all systems / subsystems –Obtain from specifications or measurements –You then show how your power system will provide the required voltage, currents and power for the mission required time Need to take into account loss due to temperature and voltage conversion More detailed talk on this subject on 3/11/03

7. Section 4.0 Other Everyone had difficulty figuring out how to pick an appropriate sensor / ADC – How do you condition the sensor for the ADC? – Talk on Data Acquisition on 3/11 Everyone had problems with thermal – Talk on Thermal issues on 3/13 Mechanical design was not developed – Related to thermal – Talk on Mechanical issues 3/13

8. The Development Phase Detailed in-depth study including –Test hardware concepts by prototyping –Finalize designs –Purchase long lead items (identified at PDR) –Establish interface controls –Complete fabrication plan –Finish integration & test plans –Complete operations & data analysis plans From 1/21 Project Overview

9. Critical Design Review (CDR) Organized by the ACES Program Results from your development phase Determines whether you are ready to begin building your payload Include written report and oral presentation Precise date should be identified during PDR From 1/21 Project Overview

10. Section 6.0 Construction Software – How will you get data OUT of storage? – How do you verify that your software works? Testing – Listing the environment characteristics is NOT testing – Testing is quantitatively verifying that your subsystems work integrated payload works payload will operate correctly under flight conditions Calibrations – What needs to be calibrated? – How will you do the calibration? – What do you do with the calibration data?

11. Data Acquisition & Analysis What is your data rate, format & volume? What is a Data Analysis Plan? –All steps & components necessary to get results –How do you get data off your payload? –What is the analysis platform? –What processing are you going to do? “busting” data from your format applying calibrations correlating with other datasets –What data products will you produce? –What software will you use? –What software needs to be developed?

12. Management & Schedule What is Interface Control? – Listing your interfaces is in System Design – Defining your interfaces is in detailed design – How do you assure that ALL parties know about, agree to & will build subsystems with the correct interface How do you develop a WBS and use it to establish a realistic schedule? – Review B. Ellison’s presentation

13. The WBS should be specific Include only the tasks you are actually going to do –Changing a few words in a sample WBS is going to lead you down the wrong path WBS should not be presented down to more than 2 nd or 3 rd level Use one level more than presented to estimate effort for task

14. Timeline follows the WBS Assign personnel to each task – Tasks by different people can be done in parallel – Tasks by same person must be sequential What is the task dependency? – What tasks must be completed prior to the start of a task (e.g. Can’t integrate payload unless all subsystems are done) Need to distinguish between work time and calendar time Would be wise to include contingency Identify milestones or major accomplishments Link tasks together with a Gantt chart

15. Budgets Long lead items where not always / clearly identified –Delivery requires more than 3 weeks –Need to get requisition forms with three quotes in ASAP All payloads probably have many common components –IWG should identify, specify and writeup requisition forms

16. Speaking of the IWG Not one project mentioned the IWG in their management There are potentially many components across the payloads that could be common – Develop solution only once – Common ADC, RTC and/or Memory chips – Common Data Format – Common Data Retrieval software – Common Data Processing software – Common parts pools (e.g. resistor, capacitor kits) IWG should meet regularly to address such issues