# Comparison between DORIS oscillators on Jason satellites in terms of radiation sensitivity

**CoAuthors**

**Event: **2016 IDS Workshop

**Session: **Precise Orbit Determination and clock

**Presentation type: **Type Oral

Radiations induced by protons trapped in the South Atlantic Anomaly (SAA) damaged the Ultra Stable Oscillator (USO) provided by the DORIS (Doppler Radiopostioning Integrated on Satellite) system, essentially on the Jason orbit (at 1336 km).

Variations in the relative frequency bias were observed on Jason-1, resulting in data elimination. Despite the growing complexity on the response of the USO to strong radiation influences notably on the short term, a first model has been established [Lemoine and Capdeville, 2006].

The new DGXX generation of DORIS USOs on Jason-2 since 2008, and then on Jason-3 since January 2016, showed a priori, a much less frequency response to radiation effects. This is probably due to a better pre-treatment (pre-irradiation to decrease the sensitivity) of quartz oscillators. Thanks to the picosecond short term stability of the ground-to-space time transfer from a laser ranging station provided by the Time Transfer by Laser Link (T2L2) experiment on-board Jason-2, a recent model (precision of a few 10−13 showed a maximum frequency peak of 1-2 10−12 in term of relativity frequency bias above the SAA area [Belli et al., 2015]. In addition, it has been proved that the USO response tends to decline with age.

Now, we present results about a simultaneous analysis of both relative frequency biases for Jason-2 and Jason-3 which have the same orbit, same phase, same attitude and same platform. We compare the sensitivity of Jason-3 to one of Jason-2, not for the same period, but for the same USO age (since the launch of each mission). In doing so, the expected larger sensitivity of the Jason-3 is estimated to be just 20% above the Jason-2 for the same age.

References

[Belli et al., 2015] Belli, A., Exertier, P., Samain, E., Courde, C., Vernotte, F., Jayles, C., and Auriol, A. (2015). Temperature, radiation and aging analysis of the {DORIS} ultra stable oscillator by means of the time transfer by laser link experiment on jason-2. Advances in Space Research, pages –.

[Lemoine and Capdeville, 2006] Lemoine, J.-M. and Capdeville, H. (2006). A corrective model for jason-1 doris doppler data in relation to the south atlantic anomaly. Journal of Geodesy, 80(8):507–523.

Variations in the relative frequency bias were observed on Jason-1, resulting in data elimination. Despite the growing complexity on the response of the USO to strong radiation influences notably on the short term, a first model has been established [Lemoine and Capdeville, 2006].

The new DGXX generation of DORIS USOs on Jason-2 since 2008, and then on Jason-3 since January 2016, showed a priori, a much less frequency response to radiation effects. This is probably due to a better pre-treatment (pre-irradiation to decrease the sensitivity) of quartz oscillators. Thanks to the picosecond short term stability of the ground-to-space time transfer from a laser ranging station provided by the Time Transfer by Laser Link (T2L2) experiment on-board Jason-2, a recent model (precision of a few 10−13 showed a maximum frequency peak of 1-2 10−12 in term of relativity frequency bias above the SAA area [Belli et al., 2015]. In addition, it has been proved that the USO response tends to decline with age.

Now, we present results about a simultaneous analysis of both relative frequency biases for Jason-2 and Jason-3 which have the same orbit, same phase, same attitude and same platform. We compare the sensitivity of Jason-3 to one of Jason-2, not for the same period, but for the same USO age (since the launch of each mission). In doing so, the expected larger sensitivity of the Jason-3 is estimated to be just 20% above the Jason-2 for the same age.

References

[Belli et al., 2015] Belli, A., Exertier, P., Samain, E., Courde, C., Vernotte, F., Jayles, C., and Auriol, A. (2015). Temperature, radiation and aging analysis of the {DORIS} ultra stable oscillator by means of the time transfer by laser link experiment on jason-2. Advances in Space Research, pages –.

[Lemoine and Capdeville, 2006] Lemoine, J.-M. and Capdeville, H. (2006). A corrective model for jason-1 doris doppler data in relation to the south atlantic anomaly. Journal of Geodesy, 80(8):507–523.