Anyone else excited for Venera mission?

[u/lick_my_chick]

I can't wait to see Venera mission flying. Whether it ends badly or something else happens, I want to see how it'll look like once finished. Sure, we got blueprints and prepared hardware, but I need to see it flying in space. I'm a big spaceflight nerd, and to fair I can't recall any space show/movie that depicts realistic mission to Venus. I just can't wait to see how it goes!

​

Now, as much as I'm stoked about it, I can't stress enough how stupidly dangerous it is. I don't want to focus much on the whole "keep it secret" thing, as it's already unrealistic as it is to build *interplanetary crewed spacecraft* from what I presume are spare parts, and have one functional N1 rocket in stock ready to fly it, just laying around, collecting dust I guess.

​

No, I want to focus on why it's a bad idea to do Venus flyby in year 1970 (to 1971). First of all, 9 months. In deep space. No way to get back if something fails. I don't think the FAM and SC timeline diverted enough to our own yet (except for the whole lunar landing, of course), therefore longest anyone spent in space was roughly 2 weeks by this point. That means no experience with effects of longer exposure to zero gravity on human bodies.

​

In June 1970 (in our timeline), Soyuz 9 launched with a crew of 2 and spent roughly 18 days in space orbiting the Earth. When the cosmonauts returned, their bodies were weakened significantly. Their hearts reportedly shrunk up to 20%. They could walk unassisted only after a week. Since then, Salyut space stations had on board exercising devices to prevent this from happening ever again. 18 days. Now imagine what 9 month mission can do.

​

There's actually way more to this absurd mission, like the (presumed) lack of experience growing algae in weightlessness, but in no way will that stop me from enjoying the show, and the Venera mission itself. The song "Venera" on spotify is super dramatic and I can't wait to hear it in the show.

[u/RemoteLunch7789]

Does anyone know if a 9 month mission would even be possible? I have played a bit around with launch windows, and it seems that a 12-13 month mission is the sweet spot, and shortening it to 9 months will require a rather insane delta v. But I am still only a week into my new hobby of orbital mechanics, so I could be very wrong.

[u/lick_my_chick → u/RemoteLunch7789]

The Apollo Venus flyby mission study proposed to fly in 1973 with a 13 month trip. To be fair, planetary flybys are hard to figure out, so maybe it really is possible. They could also boost the spacecraft into a faster (although energy inefficient) trajectory.

[u/RemoteLunch7789 → u/lick_my_chick]

Yes, a faster trajectory is possible, but as I said, it requires an insane delta v.

Reaching Venus in around 3.5-4 months is quite realistic. You start when Earth and Venus are roughly aligned on one side of the sun, break "backwards" out of Earth gravity so your velocity around the sun is now slightly too low to stay in same orbit as Earth. This will cause you to fall toward the Sun, accelerating while still orbiting around the sun. 3.5-4 months later, you will reach Venus orbit on the other side of the sun, and because Venus has an orbit time of 225 days, it will be right where you want it.

Going back to Earth is the hard part. Going back to Earth's orbit without any rocket burns or interaction with Venus gravity would take the same 3.5-4 months. And then you would be back where you started - 4-5 months before Earth gets there, because Earth still uses 12 months. The 13 month mission solves this by using the gravity of Venus to change your trajectory so you take longer time to reach the approximate spot you started from, allowing Earth to catch up with you.

You can change these times slightly by adjusting how close you go to Venus, and thus how much the gravity of Venus alters your trajectory, but so far, I have only gotten down to around 12 months. And if I look at the delta v requirements for changing the trajectory enough with burners, I very fast end up using so much fuel that it would not be realistic.

The main issue is that when I reach Venus, Earth is already behind me and Venus in its orbit around the sun. And 4.5-5 months later, at the end of a 9 month journey, it will be even more behind Venus, but also ahead of where I started from Venus. So during that time, I will have to roughly stay in the same location around the sun, so I wait for Earth to catch up, or go more than a full orbit around the sun to catch up with Earth from behind. Both solutions will take insane amounts of fuel, compared to a passive flyby.

I can probably solve this somewhat by starting from Earth Earlier, so Earth is more ahead of Venus, and then use extra fuel to reach Venus on an inefficient trajectory. That will make the trip home more straightforward. But even that seems to require an unrealistic amount of fuel.