Detection simulation for a 2.5   M_⊕ planet in the habitable zone (P = 208 days) of a K1 dwarf presenting an activity level . Top panels: detection simulation for the 3N3 strategy. On the left, we show the raw RVs including the stellar noise (oscillation, granulation phenomena, and activity) plus the injected planet (red curve). In the middle, the periodogram of the stellar noise only (red filled curve) and the stellar noise plus planet (black line) is represented. The horizontal lines correspond from top to bottom to the 0,1% and the 1% FAP. Finally we show on the right the raw RVs binned on 1 month and folded in phase with the period of the planet. Bottom panels: the same but for the 1N1 strategy (strategy presently used for the high-precision HARPS program, one measurement per night of 15 min on 10 consecutive days per month).