DA20 Student Pilot experienced an engine failure at 500 FT AGL during approach and landed in a snow-covered field short of the runway.

Narrative

I was completing my solo long cross-country. In order to fulfill the requirements I was set up to do a touch and go. I was cruising at 9500 FT MSL. I was approaching Runway 30 on a long straight in; descending from 9500 FT to the airport elevation. I had completed the descent checklist; mixture was full rich; fuel pump was on; and I had checked the engine gauges; all indicating proper readings for a safe descent. As I was on short final; approximately 500 FT AGL; my engine started sputtering and finally failed. While it was sputtering I was checking everything: fuel; mixture; fuel pump; throttle; gauges; and tried to change the throttle to see if I could get the engine to run. After it had failed and I was not able to restart it I landed it in a field just short of the runway. The field was covered in snow so the braking system was inoperable. I landed and rolled approximately 1000 FT after which I ended up in a ditch. After I had stopped I turned off the electronics; fuel system and pulled the fuel off. I immediately called my Flight Instructor and walked to the airport pilot lounge.