They believe the object has either disintegrated in space, or it may be a spaceship from some other planet, which has the ability to nullify our radar beams.
10 seconds sound clip from the Santa Claus Conquers the Martians (1964) movie soundboard.
You can hear this line at 00:20:07 in the Blu-ray version of the movie.
Quote context
[...]
- Prepare to land. We'll set down in that field near the lake.
- Rotor rockets number one and two, fire.
- All this trouble over a fat little man in a red suit.
- Fire rotor rockets number five and six.
- Attention, crew. This is Kimar. When we've landed we'll leave the ship to investigate.
- Stay on board on constant alert for immediate blast-off.
[...]