NNG16598592R_Amendment_No._4.pdf

RFP NNG16598592R

Amendment No. 4

We received the following comments/question in regards to RFP No. NNG16598592R. We are posting our response to the question in red below for all offerors interested in this solicitation.

Paragraph 3.4.6 of the Spec States:

3.4.6 Dynamic Range of Scene

a) At a distance of 30 m the RPO IRCam shall image the Iridite aluminum Marman Ring (cf. Figure 1-7) on the Client with a SNR of at least 10 at any point in its FOV. Assume the Marman Ring is at a temperature of -15° C and has an emissivity of 0.04.

b) At a distance of 5 m the RPO IRCam shall image the Kapton MLI thermal blanket material (cf. Figure 1-

7) covering the Client with no more than 5% of pixels in saturation when the object is at any point in the

FOV. Assume the 2.0 mil Kapton MLI is at a temperature of +150° C and has an emissivity of 0.75.

Figure 1-7 shows the Marman Ring is directly adjacent to the Kapton MLI thermal blanket material.

Our question is:

Typically SNR is used to discern the ability to detect a target against its background. Signal is a relative measurement of one reference point to another. For the SNR requirement, are we to assume that the signal is the difference in camera output between the pixels viewing the Marman Ring (emissivity = 4%) and the adjacent pixels viewing the Kapton MLI thermal blanket or is the Signal the output of the

Marman Ring viewing pixels relative to the pixels viewing cold space? Or is the signal relative to some other reference point altogether? If it is the relative signal between the Marman Ring and the Kapton

MLI thermal blanket, what temperature and emissivity should we assume for the Kapton MLI thermal blanket? For the SNR calculation are we to assume the noise is the noise of the pixels viewing the -15C

Marman Ring?

NASA’s response:

The signal-to-noise ratio (SNR) referenced in requirements 3.4.6 (a) and 3.4.6 (b) concerns the ability to detect the target in question relative to the signal from pixels viewing cold space. The signal from cold space is the background in the SNR.