In 2015, I received a cold email from a SpaceX recruiter via LinkedIn. I replied that I was not interested. In 2016, I received another email. I responded that I was interested in hearing more.

I had a brief phone call with the recruiter. He asked for my resume, and I sent it. A few days later, he requested a phone call with the hiring manager.

A week later, I had the call. The hiring manager explained the company, his team, and the project. He also asked about my background and interests. Overall, it was a good conversation.

After a few days, the recruiter emailed to inform me that the next step was a take-home project (see interview question). I agreed, and he sent it via email, asking for my answer within a few days.

That same night, I spent a few hours completing the design, including full documentation, derivations, formulas, assumptions, design choices, part numbers, and next steps. I sent it over.

Two weeks later, I received a reply: "They were looking for much more technical depth into the design." This reply deeply upset me, not because they decided not to proceed, but because it was the least constructive and actionable feedback I could receive.

Why was there not enough technical depth? What were the gaps compared to their expectations? How should the solution have looked from their perspective?

I believe that after investing several hours into the design, a minimal technical feedback, taking 10-15 minutes, or at least a viable reference solution, would be a fair request. I attempted to follow up twice with the recruiter and the hiring manager, but received no reply.

What are the design considerations for a power supply input filter for a satellite application?

Given these considerations, design an input filter for a 100 Watt buck converter. Prioritize small size and low weight.

• Input voltage range is nominally 28 VDC (18 VDC to 36 VDC).
• Output voltage is 5 VDC.
• Switching frequency is 100 kHz.
• Assume power return and chassis are isolated > 1 Meg ohm.
• Environment is not pressurized.

Please document and describe your filter and state any assumptions made to complete the assignment.