Suppose the following two premises are true:
1. We discover that one of the planets surrounding Gliese is capable of supporting human life today, without any terra-forming needed whatsoever. We can breath the air, drink the water, eat the plants and animals.
2. We also discover, on that same day, that there is an unavoidable asteroid the size of Mars that will smash into Earth exactly 100 years from today, annihilating all known forms of life instantly.
Hypothetical question: Assuming the above premises were true, do you think the human race would be capable of designing, engineering, building and launching a manned ship that would successfully transport humans to Gliese, before we were wiped out by asteroids? Keep in mind, the entire human race, governments, agencies, scientists, everyone would come together combining all of Earth's resources to try and accomplish this task. Funding is not an issue. Do you think we would be successful? What would be the greatest technological challenges that we'd need to overcome?
Somethings to keep in mind:
1. Gliese is ~22 light years from our solar system.
2. There would not be enough time to send a probe to scout the solar system before launching our manned ship. However, we could send one a couple years in advance to scout the 'landing'.
3. Depending on how fast we can go, we may need to have babies on way there.
Coles Notes: With the entire human race working together and combining resources, could we build a spaceship that could successfully transport humans to Gliese in 100 years or less?