by: Christiano Daniel Abadi

Deliverables/Achievements in Spring 2000: 8 Systems Engineering Documents Overall and power budgets Gantt Chart for Preliminary Design Review

8 Systems Engineering Documents: Description: A systems-level document of UASat containing: Problem Statement Description of participants General input, output, and function of the system Requirements Testing procedure Functional decomposition and physical synthesis Audience: Public, Upper Management, Systems Engineer

Procedure: Write the documents with information gained from Team Leaders, Team Mentors, websites, and other references. Distribute to all members, mentors, and administration. Get feedback and revise. Iterate as many rounds as needed.

Contents of Documents: A general block diagram that describe the overall satellite (see OHP)

Requirements: (Disclaimer: The numbers and information in red italics are just a starting estimate and are not meant to be accurate. Cost requirements: 1.The satellite shall cost no more than $1,500,000, - to model, design, build, and test. Schedule requirements: 1.The satellite should be ready to be delivered to NASA no later than March 2004.

Requirements (cont.): Performance requirements: Mandatory Requirements Launch conditions from NASA 1.The satellite shall orbit between and 57 0 of inclination. 2. The satellite shall orbit between 250 kilometers and 400 kilometers above the earth. Requirements owned by Mechanical and Structural Analysis (MSA) 3.The satellite, when not operating, should withstand the temperature range of –20 0 C to 50 0 C. 4.The operating temperature range shall be maintained between –10 0 C to 20 0 C. Restriction from the Hitchhiker Canister (given by NASA) 5.All components of the satellite that weigh more than 9 kg shall withstand the force of gravity of no less than + 11 Gs. 6.All components of the satellite that weigh less than or equal to 9 kg shall withstand the force of gravity of no less than + 40 Gs.

Mandatory Requirements Restriction from the Hitchhiker Canister (given by NASA) (cont.) 7.The weight of the satellite shall be no more than 68 kg. 8.The height of the satellite shall be no more than 52 cm. 9.The diameter of the satellite shall be no more than 48 cm. 10.The center of gravity of the satellite shall be no more than 1.27 cm from the canister centerline. 11.The center of gravity of the satellite shall be no more than 26 cm from the separation plane. Preference Requirements (determined by the SSP) Owner of requirements: All teams. 12.The lifetime of the satellite should be no less than 1 year. 13.The units of measurements of the satellite should be in SI system (i.e.: US$, kilograms, centimeters, seconds, 0 C, (degree, minute, second for angular units), G (gravitational force), Kilohertz, Volts, and Watts). 14.The peak power needed from all components in the satellite at any instant of time shall be no more than 30 Watts.

Performance requirements (cont.): Owner of requirements: Guidance, Navigation, and Control (GNC) Team 15.The orbital altitude of the satellite should be 400 km. 16.Pointing in accuracy of the satellite shall be no more than The satellite should be able to de-tumble within 1 orbit. (De-tumbling means the ability of the satellite to stabilize itself after an accidental collision that tumbles the satellite) Owner of requirements: Sprite and Lightning (SCI 1) Team and Data and Command Handling (DCH) Team. 18.The satellite should be able to detect and store (in the satellite’s computer memory) lightning counts on average 300 occurrences per day. 19.The satellite should be able to image (photograph) and store (in the satellite’s computer memory) sprite phenomena on average 300 occurrences per day.

Owner of requirements: Power Generation and Distribution (PGD) Team 20.The power system will supply DC electricity at the following voltages: +28V, +15V, -15V, +5V, -5V, or 3.3V. Owner of requirements: Laser Communication (LCS) Team 21.The laser communication devices should transmit data uplink of 10 Mbit/sec. Owner of requirements: Tracking, Telemetry, and Command (TTC) Team 22.The radio (QFSK Transmitter for the amateur 2.4 GHz band) should transmit data downlink of 2 Mbit/sec. 23.The radio (QFSK Receiver for the amateur 1.2 GHz band, Pascat Downlink, and Pascat Uplink) should receive or transmit data of 9600 bits/sec.

Trade-off Requirements: The cost requirement has 25% weight The schedule requirement has 15% weight The performance requirements have 60% weight

Figure of Merits: Description: a number that indicates how well the system has met all the requirements. Calculated by summing all of the requirements’ score with the weight assigned to each requirements defined in the Weight Table.

Standard Scoring Function (SSF): Example: 1. The lifetime of the satellite should be no less than 1 year.

Weight Table:

Overall and Power Budget: There are five factors to juggle in deciding what instruments to chose:  Power consumption  Cost  Volume  Mass  Bandwidth

Overall Budget for UASat

Power Budget: The power budget discussion between teams has started. Negotiation on power requirements will continue. Solutions to over budget: reduce power, rationing operation time, redesign solar panel, etc.

Sample graph of the power profile for each team

Gantt Chart for the Preliminary Design Review Helped by the MIS 578 Team Propose the Gantt Chart for Preliminary Design Review Use the NASA’s IMAGE PDR as the template Iteratively negotiate with all teams to reach the readiness of PDR. Example:

Things to do next Initiate discussion between Science and LCS teams with the rest of the teams in finding out what the Science and LCS teams want to do with the data. Find out:  What kind of data will come in (in terms of bytes)?  How frequent will the data come in?  Is there any processing done in satellite?  What are the data processing and analysis plans?  What to do with old data?