You asked for specific things to get you to a spacewalk...
Study aeronautical robotics in Canada
Canada occupies a niche in the space community as the experts on robotic arms. This started with the Canadarm on the Space Shuttle, and continued with the Canadarm2 and Dextre on the ISS. The Canadian government pays for the design, construction, and support for the robotic arms, delivering a complete product to NASA. In exchange, the U.S. has promised to get Canadian astronauts into space. The arrangement has been good for both countries, and it is likely to continue in the future.
There have been 12 people given the title of Canadian astronaut (let's call them "Canauts" for short) plus one Canadian space tourist. Four Canauts have served on missions installing or operating robotic arms; three of these Canuats performed spacewalks to work on the robotic arms (including the famous Chris Hadfield). (No other country has had 25% of their astronauts do spacewalks!) Another four Canauts have flown on medical or scientific missions; two of these were later hired by NASA as divisional directors (life science & space medicine). The remaining four Canauts haven't flown (yet?), but three of these became "aquanauts" in a long-term underwater NASA experiment.
As of 2018, Canada is one of the most welcoming countries for immigrants. One Canuat (Bjarni_Tryggvason) is an immigrant and flew on the Space Shuttle for a scientific mission.
While you are still in high school, make sure you do the following:
- Learn English really well. You won't get into any Canadian university without a TOEFL score of at least 90; in some cases, 100. You need excellent grammar skills, which you will not pick up from the Internet.
- You need to be very good at mathematics. Learn as much calculus and linear algebra (vectors and matrices) as you can.
- Take as many science courses as you can. Try to have at least one college-level science course done before finishing high school.
- If your school has a robotics club or team, join it. The same with an astronomy club.
- Buy a robotic arm kit on the Internet. Build it. Reprogram it to do something useful. Write about it on your college admissions essay.
- Research and apply to colleges in Canada.
Good colleges for astronauts in Canada include:
McGill University is the "Harvard of Canada". It's also as difficult to get into as Harvard or Cambridge. It is always ranked as the #1 Canadian University for biology, chemistry, medical school, and overall. As an engineering school, it consistently ranks 2nd or 3rd in Canada. Four Canauts earned degrees from McGill. It offers a master's degree in aerospace engineering.
University of Toronto consistently ranks as the 3rd or 2nd engineering school in Canada. Three Canauts earned degrees from Toronto. It offers a master's degree in aerospace engineering.
Three Canuats have degrees from the Royal Military College. But you can't get in until you are a Canadian citizen. Once you have that, you could get a master's degree in aerospace engineering there.
Waterloo University is the "MIT of Canada", with consistently the #1 engineering school. It doesn't have an aerospace engineering program, and no Canauts went there, but it still is respected worldwide. With a Waterloo degree, you'll never have a problem getting a job anywhere in the world.
Other schools to consider: York University, University of British Columbia, University of Alberta, McMaster University, Simon Fraser University (good robotics program), University of Victoria, University of Manitoba.
Your first four years are your bachelor's ("undergraduate") degree. During this time:
- If you are going the robotics route to being an astronaut, choose a degree among mechanical engineering, electrical engineering, physics, engineering physics, or computer science.
- If you are going the science/medical route to being an astronaut, choose a degree among biology, chemistry, physiology, mathematics, physics, or biomedical engineering.
- Study hard and get the best grades you can.
- Continue to learn English.
- Take 3-4 Russian language courses. This will put you above other astronaut candidates.
- Try to become a Canadian citizen. You will need this to become a Canaut.
- Research and apply to graduate school.
Every Canaut has earned a master's degree, after they finished their bachelor's degree. Some even earned a third degree (Ph.D. or M.D). These are all called "graduate" degrees. If you are going the robotics route, get a master's degree in an engineering field (mechanical, electrical, aeronautical) with a research program specifically in robotics; then get a job at MacDonald-Dettwiler. If you are going the scientific/medical route, go to medical school at McGill, then do a family medicine residency at the University of Toronto.
Yeah, this will take at least 10 years to do. But by then, the ISS will likely be obsolete and in the process of being replaced. You can bet that the new space station will have a Canadian robotic arm, and that a Canadian astronaut will be doing a spacewalk to install it. They will be looking for astronauts just as you have finished your education!