SEDSAT-2 Program Design Notes 20070411

From SEDSWiki

Talked to Ed before his trip to Barcelona the other day, and he suggested a very interesting idea to expedite the initial design of SEDSAT-2 -- essentially, design by negotiation. What? Here: each of the mass-bearing subsystems -- Structure, Payload, Attitude Control, Power, and Communications -- each start with a percentage of the total mass, which is 1kg for a CubeSat. Here is how we'll start:

1. Structure: 300g
2. Payload: 200g
3. Attitude Control: 100g
4. Power: 250g
5. Communications: 100g
6. Margin: 50g (can't use this)

Total: 1000g

Note: Systems team will be responsible for negotiating mass trades between subsystems.

Now, a new schedule is needed to get things on track... let's aim for a Payload Selection Review (PSR) in about six weeks...

• 29 April: Payload Subsystem presents final concepts for payload for team to discuss.
• 6 May: Entire SEDSAT-2 team chooses a payload.
• 13 May: Outline of SEDSAT-2 Payload Selection Study (PSS) due.
• 20 May: First draft of SEDSAT-2 Payload Selection Study due.
• 27 May: Final draft of SEDSAT-2 Payload Selection Study due. Payload Selection Review (PSR) begins, reviewed by our esteemed advisers.

But everyone needs something to do for the PSS, or it's bogus; no one wants to sit around and watch the Payload team have all of the fun. And that's fine -- there is plenty for everyone to do. Here is the initial list of what is expected to be included in the PSS...

• Attitude Determination and Control.
  1. List and discuss inputs and outputs of subsystem.
  2. List and describe functions of subsystem. Consider specifically how to support the payload.
  3. Assuming a maximum mass of 100g, describe a conceptual system for maintaining attitude control.
• Command and Data Handling.
  1. List and discuss inputs and outputs of subsystem.
  2. List and describe functions of subsystem. Consider specifically how to support the payload.
• Communications.
  1. List and discuss inputs and outputs of subsystem.
  2. List and describe functions of subsystem. Consider specifically how to support the payload.
  3. Assuming a maximum mass of 100g, describe describe a conceptual system to transmit and receive telemetry from a 600km orbit.
• Ground Control.
  1. Assume spacecraft can send communications to the surface 24 hours per day. Discuss concepts for ground stations to receive, store, and process continuous communications. How do different orbits affect this? How can stations be distributed around the globe to support this?
• Payload.
  1. Discuss different payload concepts that were selected.
  2. Perform trade studies to select payload for mission.
  3. List and discuss inputs and outputs of subsystem.
• Power.
  1. List and discuss inputs and outputs of subsystem.
  2. List and describe functions of subsystem. Consider specifically how to support the payload.
  3. Perform an analysis on the amount of power that can be collected if all six sides of the CubeSat are covered in solar panels.
• Structure.
  1. Perform an analysis on previous CubeSat structures. Consider the materials and masses of these satellites. How does this relate to the SEDSAT-2 mission?
  2. List and describe the different environments that structure will need to survive.
  3. List and describe functions of subsystem. Consider specifically how to support the payload.
• Systems.
  1. We will have our Preliminary Design Review (PDR) on 22 September 2007 in India and do integration and testing (I&T) of the satellite in 2008 in the UK. In Summer 2007 we will have a System Definition Review (SDR). Develop a schedule to meet these deadlines, and consider what actions, milestones are necessary.
  2. What is a PDR? What is an SDR? What will be required for I&T? Develop definitions for reviews. Consider how these reviews are conducted in the industry.