12 SpaceX Software Engineer (New Grad) Interview Questions (2026)

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SpaceX interviewers screen hard on mission fit. Tie to the mission (making life multiplanetary). Mention a specific launch, vehicle, or program you've followed. If you've toured a facility, watched launches live, or built related projects, mention it. Avoid 'aerospace is cool' — too thin. Be ready to defend why SpaceX over Blue Origin / Rocket Lab / Anduril.

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STAR. SpaceX expects high intensity. Pick a project where you put in real hours, made hard calls under pressure, and shipped a meaningful outcome. Show endurance and ownership — not 'I delegated' stories.

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STAR. SpaceX operates on launch-window deadlines — you can't slip a Mars transfer window. Pick a project where the deadline was real and immovable. Show what you cut, what you didn't, and how you communicated tradeoffs.

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STAR. SpaceX hires generalists — they want signal you'll learn rocket physics even if you joined as a web developer. Pick a project where you stepped into unfamiliar territory and shipped useful work. Show curiosity.

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Two pointers, swap from outside in. O(N) time, O(1) space. Edge cases: empty string, single character. Be ready for the follow-up: reverse words in a string (reverse whole string, then reverse each word).

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Recursive DFS: 1 + max(depth(left), depth(right)). Base case: null returns 0. O(N) time, O(H) space. Iterative variant: BFS counting levels.

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Stack. Push opening brackets. On closing bracket, pop and check match. Empty stack at end = balanced. O(N) time, O(N) space worst case. Edge cases: empty string, only openings, only closings.

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Kadane's algorithm. Track current_sum and max_sum. For each element: current_sum = max(element, current_sum + element). Update max_sum. O(N) time, O(1) space. Edge cases: all negative (return max single element), empty array.

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Application creates payload. TCP segments it, adds headers. IP wraps with source/destination. Link layer (Ethernet/WiFi) adds frame. Routers forward IP packets toward destination. Receiver reverses the stack. Discuss what changes with TLS, NAT, packet loss recovery. SpaceX's Starlink team cares about networking depth.

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Mutex = mutual exclusion lock, binary, owner concept (only the locker can unlock), used to protect critical sections. Semaphore = counter with wait/signal operations, no ownership, used for signaling between threads (e.g., bounded buffer producer/consumer). Mutex for protecting state; semaphore for resource counting.

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Token bucket: bucket holds N tokens, refills at rate R. Each request consumes one token; if none available, reject. O(1) per check. Alternative: sliding window log (more accurate, more memory). Discuss tradeoffs and where each fits. SpaceX's ground systems use these for API protection.

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Vehicles publish via downlink to ground stations. Ground stations forward to ingest. Time-series store + real-time dashboards + alerting. Discuss scale (thousands of satellites, dozens of channels each), gaps (satellite-not-in-view windows), and downlink bandwidth budget (compression, priority queues). SpaceX's domain — show you've thought about the physics, not just the data layer.