I'm currently exploring Vault 22 for a couple of quests: There Stands the Grass and I Could Make You Care. I've just spoken with Keely and downloaded the experimental data needed for the quests from the terminal on the 5th floor. Additionally, I have found Keely and found out that she wants to destroy the plants by flooding the vault with a flammable gas and igniting it.
I'm not sure if I'll have to go back to the Vault to re-download the data once I've completed one of the quests, and I don't know igniting the gas will affect my ability to re-download it (i.e. if the flames will destroy the terminal and the data).
If I choose to help Keely, will I be able to go back down to the 5th floor of Vault 22 and get the data again?
Best Answer
I can confirm from personal experience at least part of what's listed in the wiki page that DCShannon linked to:
So igniting the gas will not affect your ability to get the data - assuming that you survive! However, as the summary paragraph above suggests, helping Keely will affect your options with respect to completing There Stands the Grass.
What I did, on multiple playthroughs, was choose this option.
Since you mentioned Veronica's companion quest, I Could Make You Care, there is an option specific to the combination of the two quests.
There are several other options, some similar to the two above and others on a somewhat different path. To answer your precise question, you will not need to re-download the data (that's not an available choice), but you may find that you need to approach something differently once you choose to help Keely.