[Sls-slp] Proximity Use Case - Landed Asset Hails - Multiple Orbiters available to Support

[KAZZ, GREG J. (MSFC-HP27)[MOSSI2]]

Dear SLP WG member,

Please review my attached presentation for the Spring 2026 SLP WG meeting and let me know if you have any comments. It concerns the operability issue of when multiple orbiters are in the field of view of a landed proximity asset while the landed asset hails. Either orbiter could in theory support the landed asset. However, the landed asset is programmed in this case to expect comm support from only a specific orbiter, whose destination SCID the lander knows a priori. The concern is that if the landed asset doesn't provide its Source SCID to the orbiters, there will be no way to discriminate which of the two orbiters should service the landed asset. It could lead to an unending collision scenario, in which each orbiter continues to respond to the landed asset's hail (or until the lander gives up but doesn't receive any service.) To avoid that problem, the landed asset provides it's source SCID to the relays via either option 1: put the Source SCID in the LEC directive (and make it more generic by adding the S/D ID) in the hail frame or option 2: utilize the directives already defined in the protocol, i.e., put "Report_Source_SCID" directive in front of the LEC directive in the hail frame. I have my preference but would like to know yours. Looking forward to a discussion of this issue at our SLP WG meeting.

Thanks much,
Greg Kazz
NASA-MSFC
SLP WG Chair
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