silver elongated clam shaped craft over grand junction, coloradoOn or about 03/15/05 my friend Debbi and I were walking from her house to my house next door. Grand Junction, Colorado has a busy airport with lots of jet traffic so seeing aircraft is a very common occurrence. As we walked the short distance to my house I spotted a very unusual craft flying and pointed it out to Debbi. This craft appeared to be approximately 140 ft. long, approximately 50 feet wide and nearly 40 feet thick. The craft had no lights, markings and no control surfaces. It was silver on the top and sides and appeared to be flying at approximately 150 m.p.h. as it approached our location. The craft approached our general location and gradually slowed to a hover. We had to look up to see the object at about 65 degrees above our heads.As best I can estimate, the object was perhaps a quarter of a mile (south) from our location and stopped flying and began to hover about half a mile (east) from our location at perhaps 8,000 foot level. Grand Junction is approximately 4600 above sea level and is surrounded by mountains that reach the 10,000 foot level 12 miles to the east. Craft was flying from west to east in direction. The craft made no noise at any time during flight or hover. The weather was clear and had scattered puffy cumulus clouds from 8-11 thousand foot level. Air traffic was light on that day. Craft was between the airport and the usual traffic pattern for the airport. No planes approached the craft or airport during observation.Total observation time was perhaps 20 minutes. At first we watched the craft fly toward our location then after passing our location it slowed to a stop and began to hover. After a couple minutes I went inside and obtained a pair of binoculars to see the craft better. It was easy to see with the naked eye but since I could not see markings, lights or control surfaces I was sure binocular would show some kind of control surfaces. After I brought the binoculars back outside I used them to see the craft with lots of detail. The binoculars were easily able to see lots of detail and confirmed that the craft was slowly rocking side to side; the craft had no control surfaces on the back or sides, no visible vent holes or windows or light fixtures. No markings of any kind. The texture of the crafts skin appeared to be similar to silver metal but no rivets or visible joints. It had a distinct division from top to bottom and the underside was shadowed from sunlight with a line half way between top and bottom with sharp edge in the middle of the craft running from front to back. The back was wider than the front but was very similar to the front of the craft.I have about 200 hours as a student pilot but have not been active in aviation for nearly 10 years but love aircraft; this was no aircraft I have ever seen before. I am retired from California state service as a psychiatric technician and currently work part time for the state of Colorado in the same capacity.My assumption is and was that this must have been some kind of experimental unmanned craft; perhaps a small electric powered gas filled craft. I was unable to understand how the craft flew with no noise and the only way it could hover without noise was if it was filled with gas. It was not a conventional design because the power source for flight had to be inside the craft but there were no signs of vents or rudders or elevators. A rotating jet of some kind inside the craft with vents that close up seemed the only possibility to me based on my limited knowledge of lighter than air craft.I have no memory of seeing the aircraft power it self after reaching our location and after some twenty minutes the clouds obscured our view of the aircraft. A general description of the craft would be a streamlined, smooth surface elongated clam shape. Stopping a craft near the approach pattern of an airport, behind a cloud seemed very foolish to me at the time. No reports heard of that or other sightings. Reluctant to mention the sighting because have no reason to believe that it was other than a man made experiment craft, but just not sure what it could have been.((NUFORC Note: Witness indicates that date of incident is approximate. PD))