There’s something that shows up repeatedly when you look at talent retention across Series A and Series B space companies: engineering tenure is shorter than founders expect. This turnover sits in a range that should concern any founder or Head of Engineering planning for the next two years.
It’s long enough that the departures don’t feel like a crisis. The engineer onboarded, contributed, shipped work. But it’s short enough that the company never fully captured the return on the investment it made to hire them, and it’s about to spend again to find their replacement.
The Hidden Math of Space Sector Turnover
In most industries, the cost of replacing an employee is estimated at one to two times their annual salary. In the space sector, the real cost is higher, and most of it doesn’t show up on a spreadsheet.
When a senior systems engineer leaves 18 months into a program, the obvious costs are recruiting fees, onboarding time, and the ramp period for their replacement. The less obvious costs are what they take with them: institutional knowledge about the program’s technical decisions, relationships with vendors and partner organizations, and an understanding of the regulatory landscape that took months to build.
In clearance-required roles, the replacement timeline is longer than in other sectors. Finding an engineer with the right technical profile, the right clearance level, and a willingness to work onsite at a secure facility isn’t something that happens quickly. A role that was open for four weeks the first time around could take eight or twelve weeks the second time. That’s eight to twelve weeks where the program is either understaffed or relying on someone else to absorb the workload.
For companies approaching their next fundraise, there’s a valuation dimension too. Investors evaluating a Series B company are looking at whether the team has the depth and stability to execute the next phase of the roadmap. A company with consistent 18-month turnover in its engineering team presents a narrative problem: it suggests that either the work environment isn’t retaining people or the hiring process isn’t selecting for long-term fit. Neither of those is a story a founder wants to tell during a board meeting.
Why Engineers Leave at the 18-Month Mark
The reasons engineers leave growth-stage space companies tend to cluster around a few predictable themes, and most of them are preventable.
The role changed without the conversation.
At a 30-person company, an engineer hired to design thermal systems might find themselves managing a team, coordinating with suppliers, and attending program reviews six months later. That scope expansion isn’t necessarily unwelcome — but if it happens without acknowledgment, without a title adjustment, and without a compensation conversation, the engineer starts to feel like the company is getting more than it’s paying for. By month 14, they’re taking calls from recruiters.
Compensation hasn’t kept pace with the market.
Space sector salaries have been rising steadily. The average US space industry salary reached $135,000 in 2023 (SatNews), and for senior engineering roles in clearance-required environments, the numbers are significantly higher. A company that hired an engineer at market rate 18 months ago may now be paying 10-15% below what that same person could earn by moving. If there’s no proactive adjustment, the market makes the adjustment for you – and it usually comes in the form of a resignation.
The technical challenge plateaued.
Engineers who join space companies are often drawn by the complexity of the work. Building spacecraft, developing mission-critical software, solving problems that haven’t been solved before – that’s what pulls people into the sector. But growth-stage companies sometimes shift priorities as they scale. The work that was exploratory and technically challenging at 20 people can become routine and process-heavy at 60. When the engineering work starts to feel like maintenance rather than creation, the engineers who were most attracted by the original challenge are the first to leave.
There’s no visible career trajectory.
At an early-stage company, career paths are often implicit rather than defined. Everyone wears multiple hats, promotions happen organically, and the assumption is that growth will create opportunity. That works for a while. But around the 12-month mark, engineers start asking themselves where they’re headed. If the company can’t articulate what a senior engineer’s path looks like over the next two to three years (not in a corporate framework sense, but in a practical “here’s how your role evolves as we scale” sense), the answer they get from a competitor will be more compelling than the silence they’re getting internally.
What Getting Retention Right Looks Like
The companies that retain engineers through the critical 18 to 36-month window tend to do a few things differently, and none of them require a massive HR infrastructure.
They have compensation conversations before the engineer does.
Proactive salary reviews – even small adjustments – signal that the company is paying attention to the market and values the person enough to stay ahead of it. Waiting until someone has an external offer and then counter-offering is the most expensive and least effective version of retention.
They make scope expansion explicit.
When an engineer’s role evolves, the best companies acknowledge it formally: new title, adjusted compensation, a conversation about whether the new scope is what the person actually wants. This takes 30 minutes and costs almost nothing, but it’s the difference between an engineer who feels invested in and one who feels taken advantage of.
They keep the technical challenge alive.
This doesn’t mean every engineer needs to be working on unsolved problems every day. It means there’s a deliberate effort to ensure that the people who joined for the technical complexity still have access to it, even as the company matures. Rotation between programs, involvement in architecture decisions, and time allocated to R&D – these are relatively low-cost retention tools that signal the company still values engineering depth.
They talk about the future before the engineer stops believing in one.
Career conversations at the 6-month and 12-month marks are more valuable than any retention bonus. An engineer who can see a clear path – whether that’s technical leadership, program management, or deeper specialization – is significantly less likely to leave than one who’s guessing.
The Bottom Line
Retention isn’t a downstream problem you solve after someone gives notice. In the space sector, where replacement cycles are long, clearance requirements narrow the pool, and institutional knowledge is hard to rebuild, retention is part of the hiring equation from day one. The companies that understand this keep their engineers past 18 months and build the kind of team stability that compounds over time. The ones that don’t are hiring for the same roles every year and a half – and wondering why it keeps getting harder.