Sullurpeta is the nearest town to Sriharikota. It is about 20 km away. Sullurpet is fairly well-connected to Chennai, which is about 80 km from there. To get to Sullurpet from Chennai, get to the CMBT(Chennai Mofussil Bus Terminus) at Koyambedu in Chennai. Buses to Nellore, Tada etc. will most probably take you to Sullurpet. You will find most of these buses on Platform 3(Bus Bay No. 18, 19). The travel time from CMBT to Sullurpet is 2 hours, along NH 5, a four-lane road. Once at the Sullurpet bus stand, get to the 'SHAR'(Sriharikota Range)bus stand, which is about a kilometer or two away. You could either take an auto or perhaps a share-auto to get there. From the 'SHAR' bus stand, bus service to the Space station(which is the only thing at Sriharikota)is available, although getting into a jeep or a share-auto would be the best way to get there. A word of caution here, you might have to stand on the foot board in the rear end of the jeep or sit in the driver's seat and yet not drive the jeep!! The jeep drive would cost Rs.10 per person and the share auto even lesser. The drive is extremely beautiful with the Pulicat lake on both sides of the road. The Pulicat Bird Sanctuary is also on the Road and if lucky, you might spot some Pelicans too!
You could take an electric train from Chennai Central to Sullurpet,this would actually work out cheaper than the bus and is definitely more comfortable.The travel time is around 2 to 2.5 hours by train.
On being permitted to enter the Satish Dhawan Space Station, one could tour the whole place and have a look at the launch vehicles and pads from up-close. Typically, without permission, one cannot enter the Space Station. The security during a launch is further beefed-up, however the launch can be watched from outside the Space Station itself.
Get out the way you came in. The Sullurpet-Srihariota road is the only road that touches Sriharikota and is the only way in and out of it.