You asked about Aerospace
42 people built something like it. 3 are gone.
That is 7% of the ones whose fate we could settle, against 23% across the whole register. 1 were acquired.
| Launched | What it was | Today |
|---|---|---|
| 2016-01-01 | YCBoom Economically and environmentally sustainable supersonic travel · boomsupersonic.com | still up |
| 2022-01-01 | First electric business aircraft designed for hydrogen propulsion · beyond-aero.com | still up |
| 2022-06-01 | YCQuindar Datadog for Space · quindar.space | still up |
| 2021-01-01 | YCAlbedo Full-stack VLEO satellite missions · albedo.com | still up |
| 2025-09-01 | YCIcarus Stratospheric birds for defense · icarus.one | still up |
| 2019-01-01 | Heart makes electric airplanes with an all-electric range of 250 miles · heartaerospace.com | still up |
| 2021-01-01 | YCREGENT All-electric seagliders for fast, affordable regional transportation · regentcraft.com | still up |
| 2023-06-01 | YCHyLight Unmanned airships for inspecting our critical assets · hylight.aero | still up |
| 2021-06-01 | Turning space into a transportation layer for Earth · inversionspace.com | still up |
| 2019-06-01 | We build robots for dull, dirty, and dangerous jobs. · lucidbots.com | still up |
| 2024-06-01 | YCEntangl Find & resolve issues in data center engineering & operations using AI · entangl.com | still up |
| 2019-06-01 | Last-mile delivery for satellites. · epic-aerospace.com | still up |
| 2020-01-01 | Developing supersonic UAVs as a pathway to quiet supersonic flight · exosonic.com | gone |
| 2025-01-01 | Reusable Satellites · reditus.space | still up |
| 2024-06-01 | YCVendra Custom Parts, Manufactured in America 🇺🇸 · vendra.io | still up |
| 2021-06-01 | Near Space Flying Machines · kalamlabs.in | still up |
| 2022-06-01 | Airplanes anyone can fly · airhartaero.com | still up |
| 2025-09-01 | The Modular Interceptor Platform · wardstone.us | still up |
| 2026-06-01 | Autonomous construction on Earth and beyond · cosmicrobotics.com | still up |
| 2024-09-01 | YCGander Automation System for Global Aviation · usegander.com | acquired |
| 2024-01-01 | Agent-Driven Engineering · navier.ai | still up |
| 2023-01-01 | YCRadical Building persistent, high-performance infrastructure in the sky · radicalaero.com | still up |
| 2024-01-01 | YCBasalt Constellations as a Service · basalt.space | still up |
| 2022-06-01 | YCVelontra Hypersonic space plane that can take-off from any location and weather · velontra.com | still up |
| 2024-01-01 | YCElodin Unified flight software and hardware for the mission of tomorrow · elodin.systems | still up |
| 2024-06-01 | YCSorcerer Building a nervous system for the atmosphere · sorcerer.earth | still up |
| 2026-06-01 | Mass-deployable radars for air defense · vernius.systems | still up |
| 2026-09-01 | AI spacecraft operators that lives onboard the vehicle · orcaaerospace.com | still up |
| 2021-06-01 | We visually monitor space objects for governments and defense · heo-robotics.com | still up |
| 2026-01-01 | Custom Aerospace-Grade Battery Packs · kytentech.com | gone |
| 2016-06-01 | YCReebeez Reebeez creates powerful microengines for UAVs. With a 2hr + flight… · reebeez.co | gone |
| 2024-06-01 | Building low-cost cruise missiles · aresindustries.com | still up |
| 2026-06-01 | We make silicon on the Moon, to power everything in space. · ethos-space.com | still up |
| 2026-09-01 | The fully autonomous intelligence layer in the sky. · degla.ai | still up |
| 2025-09-01 | Powering tomorrow's industrial revolution in space · zephyrfusion.com | still up |
| 2025-09-01 | End-to-end Simulation for Defense Autonomy · n0labs.com | still up |
| 2024-09-01 | AI that gets aircraft flying faster · tryforerunner.com | still up |
| 2023-06-01 | Building and Protecting an Exciting Future · singularityus.com | still up |
| 2026-06-01 | YCExosat Building a neutral, sovereign alternative to Starlink · exosat.com | still up |
| 2024-09-01 | YCConsus The fastest and cheapest way to use AI with ITAR or CUI data. · consus.io | still up |
| 2026-06-01 | YCSkymerse Autopilot for Flight Operations · skymerse.com | still up |
| 2024-06-01 | In-Space Refueling · spaceium.com | still up |
How this compares
The register re-probes every domain it holds. Some that answered last month stop answering. We send that list — what went quiet, and what it was — once a month. Nothing else.
How this was made. Show HN entries are every post from 2021 to 2023 with at least five points that linked to its own domain; code hosts and free hosting are excluded, because a repository outlives the effort behind it. Product Hunt entries needed 100 votes — a far higher bar, so they are the promoted top slice rather than a like-for-like sample. Both are judged by asking the domain whether it still answers: gone means it no longer resolves, refuses the connection, serves a parking page, or says plainly that it shut down. An HTTP error is not counted as gone — a server answering 404 is one somebody still pays for, and an audit of 25 gone-calls found two such sites alive with only a moved homepage. Y Combinator entries use the status YC publishes itself, which is why only those can say acquired. Squatted domains — a lapsed name now serving somebody else's site — are not detected, so these figures run slightly low.