No longer do you have to download large mission packs for D1 and D2 to get the one mission you're looking for. You can now find it via our searchable and sortable Missions Database. I think you're going to like it! Oh, and if you do want to download the large mission pack, it's in there too under "D1 Missions Pack" and "D2 Missions Pack."
If you'd like to submit your Descent mission to be posted on the site, see the instructions at the bottom of the mission database.