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Any change from the routine operations described in the preceding sections will entail notification to mission elements at short notice. Mission element contact details are given in Mission Element Points-of-Contact. Each mission element should ensure that their contact information remains current and notify the RSOG of any changes.

The most likely contingency will be a change in the satellite observing schedule, which could arise if there is a time-critical Target of Opportunity observation, a correction to the existing schedule, etc. For simplicity, notification of the mission elements by the RSOG will be made via an e-mail distribution list - dit@RAstron.asc.rssi.ru - which contains multiple direct points of contact for the RSOG, tracking stations, orbit determination centers, correlators, and GRT arrays. GRTs will be notified individually or collectively as necessary to inform them of the location and name of new schedule files, or of the cancellation of observations as appropriate.

Non-RSOG mission elements will also use the "dit" list to notify the RSOG (and all other mission elements) of unexpected events that may impact operations elsewhere, e.g., if a tracking station discovers that the spacecraft is in an unexpected configuration. Such notification by non-RSOG mission elements should be considered "information-only" communications that do NOT imply specific unscheduled action by other non-RSOG mission elements. When and if possible (see next paragraph), the RSOG will respond with clarification of future expectations, recommendations, or directives.

In the special case of unexpected spacecraft problems (e.g., unexplained loss of downlink signal at a tracking station), rapid notification of appropriate spacecraft operations personnel in the RSOG is possible via a pager system that is activated by email sent to RAstronsos@asc.rssi.ru to alert other mission elements to the possibility of forthcoming recommendations from the RSOG, any email sent to this address will be forwarded to the "dit" distribution. However, it will usually be necessary to wait for a Control Station operations tracking pass to better determine the satellite's status (see the RadioAstron WWW site http://www.asc.rssi.ru/radioastron/ops/Operations.html for the CS schedule). For this reason, observations should continue at all mission elements until the RSOG determines the utility of continuing and, if necessary, explicitly cancels observations.

In general, two-way communications on timescales shorter than 24 hours is most desirable between the RSOG and the tracking stations for clarification of real-time spacecraft status and information. However, the many complexities of scheduling space VLBI observations imply that meaningful changes to the observing schedule on this timescale or shorter are extremely difficult and failure-prone, except perhaps for explicit cancellations, and are therefore very unlikely. Thus, receipt and acknowledgement of such communications will be undertaken on a locally-determined best-efforts basis, especially at mission elements not directly involved spacecraft operations. Any mission element with special requirements in this regard should make them clear to the entire mission.

Since the pager system is monitored principally by spacecraft operations personnel, communications via RAstronsos@asc.rssi.ru which concern non-spacecraft emergencies are discouraged (especially Monday-Saturday in Moscow) unless a response is absolutely required within a few hours. Use of dit@RAstron.asc.rssi.ru as described below should be sufficient in most if not all such cases, with a reply from a RSOG representative usually available within 24 hours.

Since the "dit" list is also used for routine communication among the mission elements, information that is, as determined by the originator, especially time-critical in nature should be so indicated with "** RadioAstron SOS **" in the Subject line of the message. In the body of the message, the sender should indicate their name, the date, and the mission element they represent, and concisely describe the nature of the contingency. If acknowledgement from other mission elements is required or desired this should be explicitly requested. To avoid confusion, "** RadioAstron SOS **" messages (and all replies to them) should be carefully considered before sent. Only explicit directives from the RSOG should be considered authoritative instructions to alter operations (except for local determinations of safety, etc.).