CRISTA-NF - a Helium-cooled Infrared Telescope for the Atmosphere
The technical Realization
CRISTA-NF utilizes two grating spectrometers simultaneously to measure the infrared radiation of atmospheric trace gases. The incoming radiation is detected by 15 infrared detectors. The turnable primary mirror of the telescope is able to point at different altitudes in the atmosphere, which allows for vertical atmospheric scans.
The complete optics is housed in a cryostat which provides the necessary operating temperature of about - 260 oC. The cryostat holds a Helium tank with a maximum capacity of 125 liter, which accounts for 60 hours endurance. This enables the participitation of the instrument in scientific flights on two consecutive days.
A comprehensive electronics monitors and controls the instruments and records scientific data. A unique position control system calculates the exact roll position and adjusts the primary mirror accordingly.
Additional details are provided in the following list of technical data:
| Length | 1910 mm |
| Diameter of Vacuum Shell | 850 mm |
| Weight | 360 kg |
| Volume of Helium Tank | 125 l |
| Telescope | Herschel-Teleskop (120 mm) |
| Altitude Range | 5 - 20 km |
| Vertical Sampling | 100 -300 m |
| Pointing Accuracy horizontally | +/- 30 arc min |
| Pointing Accuracy vertically | +/- 30 arc sec |
| Spectrometer | 2 Ebert-Fastie Spektrometer |
| Spectral Resolution HRS | 1000 |
| Spectral Resolution LRS | 500 |
| Time per Spectrum | 1 s |
| Time per altitude profile | 1 min |
