Hacker News Reader

Comment by xattt | Hacker News Reader

> As this is a lander that was designed to survive passage through the Venus atmosphere, it is possible that it will survive reentry through the Earth atmosphere intact, and impact intact.

I did not consider this outcome at all, but this makes sense. I am hoping the descent mechanism activates and the spacecraft lands intact.

View on HN

It will not, of course - anything that's inside is long dead, not designed for Earth atmosphere, and it had to be programmed to trigger in the first place.

In fact, the capsule could also burn up on reentry. Sure, it's a Venera-8 double designed to enter Venus' atmosphere at 11.6km/s... but it has extra mass on it (the upper stage never separated so it should look like [1]) and the capsule's CoG doesn't take all that stuff into account, which might cause it to tumble, reenter backwards, or damage it. On the other hand, it's reentering from a really low-energy orbit so it could survive the reentry - but not the impact in case it lands on the ground.

[1] https://epizodyspace.ru/01/2u/solnthe/ams/v-8/v-8.html

Marco Langbroek, who did the reentry forecast that the linked article is based on, convincingly argues[0] that the bus did separate and reenter separately (in 1981) and what remains in orbit is just the lander. There are several independent pieces of evidence that are consistent with this; the orbital decay pattern, the radar cross section and optical telescope observations all point to only the lander itself remaining.

See also his blog[1] for an up-to-date reentry forecast.

[0]: https://www.thespacereview.com/article/4384/1

[1]: https://sattrackcam.blogspot.com/2025/04/kosmos-842-descent-...

The descent mechanism would be built for the much denser Venusian atmosphere. On Earth, it may not slow the thing down enough.

> I am hoping the descent mechanism activates and the spacecraft lands intact.

I think it's a safe bet that any descent mechanism designed for the thick atmosphere of Venus is not going to function the same way on Earth.

That would be pretty cool indeed. My only concern is that the craft probably doesn't have any attitude control, so it may enter backwards or tumbling, which may limit the effectiveness of the heatshield on the probe. Even so, surely large pieces of it will make it back home intact.

If it is the same as other venera probes, it is designed so that aerodynamic forces will stabilise it into a heatshield-forward attitude

Reply on news.ycombinator.com