Nelsonmendez.com tells you how.
No all the travelers to Houston have a car to visit the different attractions of the city. One of the major attractions is the Space Center, so you definitely have to visit it.
To go to the Space Center you have the choice of taking a cab for about $70-80 from Downtown. However, if your budget is small, you can take the bus.
If you intend to go early, then you should catch routes 244, 246 or 247 before 8.00 am. For this, go to Downtown Transit Center and just walk some steps from the train and look for the sign indicating the routes previously mentioned.
Visiting the facility takes about 4-5 hours if you want to visit all the attractions. So, the convenient way is being there early. But if you don’t feel like going early, you still have the chance of catching a bus after 8.00 am.
In this case catch bus number 249, also near Downtown Transit Center in Main Street. The bus passes, I think, every hour. So, take this into account.
The bus takes around an hour to arrive to the place and stops almost in front of the main entrance of the Center. The last bus from the Space Center to Houston Downtown leaves at 5.30 pm.