From SEDSWiki

Contents 1 Summary 2 Review Board 3 Subsystem Representatives 4 Key Points of Dicussion: 4.1 Recognized needs 5 Subsystem Specific Results 5.1 Structures 5.2 Power 5.3 Payload 5.4 Ground 5.5 ADCS 5.6 Command and Data Handling 5.7 Communications 6 Conclusions 7 Design Review II

Summary

This first SEDSAT-II Design Review was conducted to analyze the progress of each of the subsystems' technical designs, as well as to ensure that the same designs were compatible, both with each other as well as the project's mission. The review was conducted online, via the Yahoo! Messenger chat client, with representatives from the Core Committee and the Systems Engineering team present.

Prior to the review meetings each subsystem was presented with the format of the review sessions and a specific set of questions to prepare for. Representatives from each subsystem, then, were interviewed successively by the Core Committee and the Systems Engineering team.

The focus of the review was an evaluation of how far the subsystem had progressed, its estimated time of completion and the obstacles or hindrances to the subsystem's progress. The subsystem representatives were also asked to present as detailed a description of design as possible, so that the design itself, and not just its progress, may be critically evaluated.

Based on the meetings conducted with each subsystem, it was found that Command and Data Handling, Payload and Power were well past the design study and had a firm design, which fall within the project's requirements, for the subsystem laid out. The Attitude and Determination Control subsystem are done with their design study and are currently working to procure component samples. The Communications subsystem is in the middle of their design study and seem to be progressing well. The Structures and the Ground subsystems are still in the earliest stages of development, and require critical attention.

There are several recognized needs which are more or less common to all subsystems. These include funding sources, more members as well as better documentation of their design.

Review Board

• Lavina Parwani, Project Manager, Philippines
• Tom Andre Nordheim, Project Manager, United Kingdom/Norway
• Anna Daurskikh, Systems Engineering Lead, Sweden/Russian Federation

Subsystem Representatives

• Sigve Haugsnes, ADCS Lead, United Kingdom/Norway
• Per Magnus Veierland, Command and Data Handling Lead, United Kingdom/Norway
• Pavan Kumar, Power Lead, India
• Steve Maughan, COMM Lead, United Kingdom
• Mansee Sahu, Structures Lead, India
• Tom Nordheim, Payload Lead, United Kingdom/Norway

Key Points of Dicussion:

• Current state of subsystem
  • Design choices
  • Rationale
• Progress since IAC-2007
• Subsystem Interfaces
  • Inputs and Outputs.
• Critical issues
• Timeframe for completion of subsystem
• Finances
  • Estimated budget
  • Sources

Recognized needs

• Further member recruitment is required, specifically for Ground, ADCS and Structures. Based on the current and required progress of the subsystems, applicants that are considered must have a strong knowledge foundation and/or experience.
• Each subsystem's page on the SEDSWiki must be updated, and kept up to date, with relevant documentation such as subsystem design, key decisions, and aid needed.
• The Ground Control and Structures subsystems are areas that need critical attention, as their progress has been extremely limited.
• Although not currently critical for most subsystems, there is a need to find sources for funding.
• A launch provider has not yet been found.

Subsystem Specific Results

Structures

This subsystem is in the earliest stages of its development. The reason for this delayed progress is that management has changed and work had to be started from scratch, as well as the fact that they lack team members. It has also been suggested that funding would be an issue.

In terms of design, this subsystem's members have completed an initial study, and have decided that they will not use a kit, but will build the satellite's structure from scratch. They are now evaluating the different components that they might use. There is no documentation of their progress, but this will be corrected, according to the subsystem leader.

The time frame provided that the members will complete the design study by March 1, 2008, at which point they will begin prototyping. They have also been tasked with completing a thermal model for SEDSAT-II, in order to aid the other subsystems in their designs for each subsystem's thermal insulation.

Power

The Power subsystem has made very good progress since the IAC-2007, and their work has been documented well. They are currently working on funding for their subsystem, and in furtherance of this, are planning to present the project to ISRO (Indian Space Research Organization) and Vellore Institute of Technology. They have also contacted Maxim and Texas Instruments for component samples in order to start work on building a prototype of the Power subsystem. The funding that they will get from other sponsors will therefore be appropriated largely towards the procurement of solar cells.

According to their own estimates they should have completed their subsystem in time for the scheduled integration. The design of the subsystem, as it currently stands, have been detailed in the following documents:

• Power Subsystem Diagram
• Power Design Review Document

Payload

The Payload subsystem has made little to no progress since the IAC-2007, but this is of no real concern nor a hindrance to the progress of the project as a whole, since a basic design had already been laid out before the conference. The team is currently about to look into modifying or improving the design to include image analysis.

The financial situation for this subsystem seems to be under control as none of the components are particularly expensive and they have been promised aid by the Aberystwyth University.

• Payload Design Review Document

Ground

There was no review conducted of this subsystem, as at the time of the review, the leadership of the subsystem was currently in the process of being handed over to Leyeah Salu. Apart from a rudimentary draft of a link budget, there has been no progress in this subsystem, which state is of immediate and critical concern. The progress of the system is also hindered by a lack of team members, so recruiting is crucial to ensure the successful completion of this subsystem.

ADCS

The Attitude Determination and Control System team has completed their design study. It does not foresee much trouble in terms of funding, however team morale seems to be low as team members are not showing up for meetings. The team has yet to provide up-to-date documentation of their progress and design as well.

With respect to design, it has been determined that active magnetics is the most suitable choice for the implementation of on-board attitude control. Attitude determination will be implemented by means of magnetometers and sun-earth trackers. The team is currently working on a proposal for utilizing thrusters for secondary attitude determination, maneuvering and deorbiting.

Command and Data Handling

This subsystem has also shown excellent progress since IAC-2007 and prototyping is scheduled for February 2008. Funding is not critical for hardware development as they have been promised backing from the Aberystwyth University, but further funds will be required for testing. One thing that is of concern is that several of the team members in this subsystem are inactive and do not contribute to its development.

The team is currently looking into a 100 mil aluminum shielding around its components. The team leader is also discussing interfaces with other subsystems. For more details regarding the current state of the subsystem design, please click on the following link to download the PDF document:

• CDH Design review document

Communications

The leadership of the Communications subsystem has recently been reassigned to Steve Maughan. The subsystem is currently in the middle of its design phase, and they have documented their progress in detail on the SEDSAT-2 Communications Design Notes page. They plan to build a prototype by June 2008, though the availability of sources for funding is a mild concern. One other potential setback to the progress of this subsystem is the lack of progress in the Ground subsystem. However, they are attempting to preempt this by working closely with the Ground subsystem to draw up the link budgets.

The design as it stands so far has been detailed in the Design Review document. The subsystem team is currently focusing on finalizing the requirements for the subsystem and finding sources of funding. Critical issues with regards to design have been identified as a need to finalize the power budget and thermal control.

Conclusions

Based on the information gathered through the design review, it has been concluded that several measures taken as a result of the SEDSAT-II progress review at the IAC-2007 have proven successful. Most of the subsystems are now back on schedule and progressing at a satisfactory pace. Structures and Ground control are however critically underdeveloped and require immediate attention.

Furthermore, it has become clear that additional funding is now crucial to the completion, successful integration and ultimately, launch of the individual subsystems, and therefore of the satellite.

In summary these are the findings of the review board:

• Overall progress is acceptable
• Structures and Ground Control are not sufficiently developed
• Additional funding is required
• Better documentation of each subsystem's development is required, in order to facilitate the compatibility of the other subsystems' design.
• More cooperation with the Systems Engineering team is required.
• A plan for finding a launch provider must be set and put in motion.

Design Review II

The second Design Review for SEDSAT-2 will be conducted on March 29, 2007. It is expected that by this date, most if not all of the subsystems will have completed the final draft of their designs and will be well on their way to begin prototyping. This is in accordance with the proposal to begin integration at the IAC 2008 in September.