In the career mode - are missions are essentially infinite, and they are just autogenerate? Or if you wait long enough you lose all the mission offers?

[glorsh66]

In the career mode - are missions are essentially infinite, and they are just autogenerate? Or if you wait long enough you lose all the mission offers?

[dci]

If you mean contracts, they are generated over and over. All contracts have deadlines for accepting (maybe except basic ones, e.g. escape atmosphere or first orbit of Kerbin) and most of them also have deadline for completing. So if you are not fine with declining offered contracts (there is money and reputation penalty for cancelling), just timewarp and periodically check mission control for new contracts.

[Xavven]

They keep generating forever.

[magnemoe]

They get recreated forever but they depend on that you done, so you will not get any Duna contracts except the basic fly by Duna until you visit, you can then get the land on Duna if you only did an flyby. 
Landing an Kerbal unlocks all mission types for Duna and probably Ike. 
 

[Sev]

On 6/1/2022 at 10:52 AM, magnemoe said:

They get recreated forever but they depend on that you done, so you will not get any Duna contracts except the basic fly by Duna until you visit, you can then get the land on Duna if you only did an flyby. 
Landing an Kerbal unlocks all mission types for Duna and probably Ike. 
 

That’s not my experience. In a new career I started last week I have had a contract offer to measure the temperature on the ground on Eve and another to place a satellite in a stationary orbit above a specific Eve sector,  despite not having left Kerbin’s SOI yet and haven’t had any offers to fly by anywhere. Perhaps it depends on difficulty level?