Altaïr's crazy stuff

[Astro826]

in the challenges tab a Mercury return is rated as 'extreme', while any of the jovian moons' return is only rated as 'hard',

According to a delta V map+a landing estimation, a Mercury return requires 5700 m/s from LEO while a Callisto return only needs 4800 (without any gravity assists). Other Jovian moons would however make it closer as you have to capture into a lower orbit.

 

[Axiom]

According to a delta V map+a landing estimation, a Mercury return requires 5700 m/s from LEO while a Callisto return only needs 4800 (without any gravity assists). Other Jovian moons would however make it closer as you have to capture into a lower orbit.

I think also you can save more Delta-V using gravity assists more easily with the jovian moon than with mercury. With the Jovian moons VEEGA puts you on jupiter no strings attached, and you can more easily do pingpong with the moons to lower your orbit. Mercury on the other hand requires a double assist from Venus + a powerered assist to hit Mercury's periapsis, you also basically have to land after that (unless you either want to V-leverage and wait 40 years or use ANAIS) which costs more fuel. Mercury also has over twice the gravity of the moons.

I guess I just thought it was harder as I remember when the galilean moons had ridicolously high gravity for no reason (like Ganymede had a gravity of 5.82m/s^2 and an orbital velocity of nearly 1000m/s)

 

[Altaïr]

I made another try on that Mercury challenge, and I broke a new record

I needed something epic for my 7000th post.

 

[Axiom]

1. Happy 7000 posts!
2. Please stop breaking the under pressure record! I was feeling proud of my 11%

 

[Altaïr]

1. Happy 7000 posts!
2. Please stop breaking the under pressure record! I was feeling proud of my 11%

I'll compete in the "with ANAIS" subcategory for that record so that it doesn't interfere with yours.
Honestly 11% is very good, especially with the limited navigation tools the mobile version offers. I recently tried a VEEGA maneuver on mobile, I literally had to re-learn how to proceed, there's no way I could match the efficiency provided by ANAIS...

 

[Axiom]

Honestly 11% is very good, especially with the limited navigation tools the mobile version offers.

I only managed to do it by doing your double venus assist

 

[Astro826]

I made another try on that Mercury challenge, and I broke a new record
View attachment 119313
I needed something epic for my 7000th post.

Altaïr you're killing me, now I'll have to do a lunar assist chain into venus assist(s?) into V-leveraging all on mobile when I decide to get a record myself

 

[Axiom]

Altaïr you're killing me, now I'll have to do a lunar assist chain into venus assist(s?) into V-leveraging all on mobile when I decide to get a record myself

You'lll defininetly have to do multiple, even 2 isn't enough to get to mercury perihelion
You'll probab;y spend like a million years V-leveraging lmao

 

[Astro826]

You'lll defininetly have to do multiple, even 2 isn't enough to get to mercury perihelion

That depends on your relative velocity to Venus, if you go for a normal Venus transfer for example, no amount of gravity assists will get your orbit low enough because more relative velocity is needed. 2 is pretty likely.

 

[Altaïr]

Altaïr you're killing me, now I'll have to do a lunar assist chain into venus assist(s?) into V-leveraging all on mobile when I decide to get a record myself

If you want a fair competition, here is my best attempt on mobile: Mercury mission
16% of remaining fuel on landing. ANAIS is so efficient that it's unfair otherwise, it even allows to complete the challenge without gravity assist.
However I don't think that lunar assists will help much: I didn't try recently, but from my experience the Moon can not provide you enough speed to reach Venus at an appropriate level. Especially that it's not very massive and can't deflect your trajectory by a lot, and as soon as your trajectory exists the Earth SOI you can't do it anymore.

That depends on your relative velocity to Venus, if you go for a normal Venus transfer for example, no amount of gravity assists will get your orbit low enough because more relative velocity is needed. 2 is pretty likely.

That's correct. Lowering the orbit doesn't just depend on the number of assists, it would be too simple. Two passes are needed because a single pass can't deflect your trajectory enough, but more assists won't help. Once your exit velocity is in the exactly opposed direction of Venus velocity the game is over. Or you have to use the V-leveraging technique, but it will cost fuel. In my opinion it's still better to aim for a low enough orbit while you're making your injection burn from LEO, because at least you benefit from the Oberth effect. V-leveraging is done through deep space maneuvers, which are by definition less efficient.

 

[Astro826]

However I don't think that lunar assists will help much: I didn't try recently, but from my experience the Moon can not provide you enough speed to reach Venus at an appropriate level.

It is quite the tedious process, but I have used lunar assist chains to gain all of the velocity to get to another planet (minus the moon transfer, so the saving is quite small). Especially without a future planning maneuver system, it takes a ton of time to get back to Earth to do the final assists. You obviously can't spend much fuel at all or you just wasted a bunch of time. I may experiment with calculating orbital resonance for this step. The assists theoretically save something like 80 m/s.