I am a parent but have some inputs for you, as I am familiar with the three campuses. Good for you to start a year early to investigate colleges. Your campus visits will be very helpful.
Mines by far is the quieter environment, its located in Golden, a small town of 20,000 residents, hilly and beautiful campus with access to hiking, skiing and nightlife in Denver. There are division 2 sports, and a lot of really serious students who are friendly. Parties are very low key. Boulder and Austin are traditional public schools with lots of other majors, should you change your mind, spectator sports, lots of parties, fraternities, sororities and many great educational opportunities in your desired majors. Boulder is much smaller than Austin, which is hovering at a million residents. Boulder is a town of 100,000, about 30 miles north of Denver which is a million residents. For its size, Boulder offers amazing fine music arts both on and off campus, hiking and skiing similar to Golden. Austin is much better known for popular music than any city in Colorado. Austin has beautiful lakes, sailing, restaurants and night life.
Boulder is home to a lot of marathoners and bike racers as well as Buddhist temples, environmental groups, liberal political groups. It is now a high cost of living, so professors are living in Longmont or other towns to the east. Athletes come to Boulder to train because of the altitude.
I think you can handle the academics at Colorado School of Mines, given your record and math score. The geosciences are phenomenal there, as the school focuses on both geophysics and geochemistry heavily in the science departments. However, astronomy is not a strong suit for Mines, but it offers some classes. I love the physics program at Mines because it will prepare you for ANY PhD program well, so geophysics, astrophysics or astronomy. You will get a lot more attention at Mines, as class size is smaller and you will not fall through the cracks, as can happen to any student, who gets distracted, at UT or Boulder.
Job placement is known to be better at Mines than CU Boulder Engineering, slightly. I am not familiar with UT Austin job placement.
Mines has the better teachers, given that they tenure teachers separately from research staff, very unusual. CU Boulder and UT Austin, tenure is based on research quality more than teaching. Yet Mines has good PhD programs too, so its very compelling for a student like you who seems headed to a research career in geosciences.
Here is one program at Mines that includes astronomy classes, and space related classes:
http://spse.mines.edu/SPSE_program.shtml
Mines offers a lot of academic support and its much smaller than either UT or CU Boulder. your PSAT math score is for sure high enough for you to get As at Mines, do not worry! It will be more work than CU Boulder to get As, but you will get a lot more out of your education.
I would guess, given its national rank, that academic level UT Austin level is the SAME as Mines, by the way, , so do not rule out Mines based on difficulty. CU Boulder Engineering goes a little slower and less difficult tests in some subjects and less homework than Mines, by a bit. CU Boulder physics is very well regarded in the graduate school, undergraduate is strong but quite large with a lot of drop outs as things get harder in upper level subjects. There are not too many girls at CU Boulder in physics is another consideration. I am not sure about UT Austin for girls in physics.
Mines, then gender ratio in physics may be higher for women than UT or CU , but I don’t know that for a fact.
Gender ratio matters a little bit less at Mines, as the academic support is so good for all students.
Mines is longer a school where half the students drop out, unless they are truly finding that engineering and science are not their interest. You may be aware, UT Austin has a tremendous reputation and rank nationally though, so I would really consider that school as you will have an A+ degree there too, but much larger class sizes. CU Boulder is ranked lower, than UT or Mines, but still very strong in geology with a lot of related majors and very very strong in physics.
I don’t know about Hispanic student support at any of these schools, but I know Colorado schools actively recruit Hispanic students and want to encourage Hispanic girls in the sciences. Look for Latino clubs at all schools, if that interests you.
I have heard UT Austin is very very difficult for admissions for Texas students by the way, but I don’t know the stats or if you are more likely to apply in Arts and Sciences or Engineering. Arts and Sciences may be easier for admissions, but look that up.
MInes, you apply to the school as a whole, so you have complete freedom to explore any science, social science or engineering major. You can major in economics at Mines too.
At CU Boulder, think about applying in Engineering, in case you want to study Engineering Physics. If you want to transfer to the physics or geology department later, in Arts and Sciences, that is very easy to do. Transferring from CU Arts and Sciences to CU Engineering at CU Boulder can be difficult, once you get to Boulder, but with your math scores and if you get As in freshman year, should be OK.