The time beetween the arrival of the Conestoga on New Terra and the planet evacuation would take 150 years (maximum), no time to develop this kind of tecnology in a harsh world (survival is priority). A lot of technology was lost in the Conestoga crash and the quiquly evacuation of the planet. The colonists have suffered (a lot) for build a simple SLV and RLV.
Want more? :yawn:
To build a kind of elevator that reaches the outer atmosphere (100Km on Earth, I think), the elevator base showld have by 10Km diameter, it showld be made of a very strong and light compound (something like polystirene reinforced with nano carbon tubes, but a lot more light and strong). A lot of power to run the facility and a ultra-fast pressurized elevator with a minimum speed of 1Km/s.
It has a lot of technical difficulties. No nation on Earth has the resorces to build and run such thing, the colonists certanly can't do it either.