Interplanetary Data Delivery: Product Design for Bulk Transfers Under Extreme Delay
Company: PayPal
Role: Product Manager
Category: Product Design & Strategy
Difficulty: medium
Interview Round: Other
Design a way to send very large amounts of data from Earth to another planet. Treat it as a product problem: explain who needs the data and why, what makes the transfer hard, which approach or combination of approaches you would choose, and how you would decide whether the system is succeeding.
```hint Two numbers per option
For each way of moving data, estimate how long until the first useful data arrives and how much data it can deliver in total over a month or a year. Users who need a fast answer and users who need a huge archive may not want the same option.
```
### Clarifying Questions
- Which planet is the destination (for example Mars), and who is there to receive and use the data: robotic missions, a crewed base, or a permanent settlement?
- How much data counts as "large": mission datasets, regular software and media updates, or entire archives copied from Earth? Is the flow mostly one-way, or must data also come back?
- How quickly must different kinds of data arrive: is a delay of minutes, days or months acceptable?
- Who is the customer and who pays: a space agency, a private company running missions, or people living there paying for a service?
### What a Strong Answer Covers
- The users and what each needs, with the data split into classes by urgency and volume.
- The physical constraints of interplanetary distance and how each one shapes the design.
- A comparison of at least two transfer approaches on delivery time, total throughput, cost and reliability, ending in a reasoned choice backed by rough arithmetic.
- How the system stays reliable and secure when a round trip takes many minutes and contact is intermittent.
- Success metrics, a phased rollout, and the main trade-offs and risks.
### Follow-up Questions
- When the Sun passes between Earth and the destination and blocks contact for an extended period, how does your design keep critical data flowing?
- People living at the destination want live video calls with family on Earth. What can your system offer them, and what would you tell them it cannot do?
- Capacity is scarce. How would you allocate it, or price it, between science missions, operations and personal use?
Overview: A product design interview question that asks how to move very large amounts of data from Earth to another planet. It tests defining users and data needs under ambiguity, reasoning about signal delay and intermittent contact, comparing transfer options, and setting success metrics for an unusual system.