Overview | | Project Title | Time Management Green Book | Approval | Approved | Document Number | 300.1 | Charter | 1.07 Time Management Working Group | Document Type | Green | Description of Document | 2) Produce a Green Book describing suitable operational domains, applications, and methods used for time correlation and synchronization. The Green Book will identify requirements for interoperable time correlation and time synchronization services. Applications that may make use of time correlation and/or synchronization include maneuvers, coordination of scientific observations, one-way ranging, docking or other robotic collaboration, and scheduling of communications links or other activities. The book will describe methods for time correlation and synchronization, including those for near Earth, cislunar, and deep space regimes. The book will separately address application domains in which a Global Navigation Satellite Service (GNSS) is or is not available. A multitude of time transfer and synchronization methods will be described, using correlation techniques such as existing CCSDS ranging methods, one way data delay coupled with trajectory data, two-way range signaling similar to that used by the Tracking and Data Relay Satellite System (TDRSS)), the use of local area time zones (e.g., rovers and orbiters around Mars), and methods using or not using explicit time code format representations in the signaling. The Green Book will also discuss the roles of clocks, frequency standards, and topics such as X-Ray Pulsars as frequency sources for timekeeping. Error sources will be identified, including limitations in orbit knowledge, calibration, and time tags. | Applicable Patents | There are no patent issues for this technology that are known by the CCSDS community | Patent Comments | | Survey of Similar Standards
Documents or Projects
Undertaken in Other Bodies
and elsewhere in CCSDS | CCSDS has developed standards for Time Code Formats (CCSDS 301.0-B-4), Pseudo-Noise (PN) Ranging Systems (CCSDS 414.1-B-2), GMSK+PN Ranging, and is in the process of developing a standard for telemetry ranging (to be included in CCSDS 401.0-B-30), PN ranging using CDMA from a Relay Satellite (CCSDS 415.1-B-1), Earth Receive Time (ERT) time stamps delivered by Space Link Extension (SLE) return frame services (CCSDS 911.1-B-4, CCSDS 911.2-B-3). Each of these standards relates to the representation of or exchange of time, or the measurement of elapsed time useful in determining the range between a reference point on the ground and a reference point on a spacecraft.
A series of IETF RFCs (RFCs 778, 781, 956, 958, 1059, 1305, 5905, 7822) describes the Network Time Protocol (NTP) and its extensions, for time synchronization over the Internet. NTP is one of the oldest Internet protocols in current use. There is not yet a corresponding set of time synchronization standards for the Delay Tolerant Network (DTN) suite.
| Resources | | Book Editor | NASA | Book Editor Resources | 6 MM | Prototype 1 | Not Required | Prototype 1 Resources | | Prototype 2 | Not Required | Prototype 2 Resources | | Prototype 3 | Not Required | Prototype 3 Resources | | Contribute | ESA, NASA | Monitor Only | CNES, DLR | Resource Comments | NASA staffing for this has been identified. ESA has expressed an interest, but staffing has yet to be confirmed. BoF meetings have regularly included 10-12 individual from NASA, ESA, and DLR. |
| | Schedule | |
Legend for Schedule Milestones
= Required for Orange Books
= Required for Green Books
= Required for Magenta Books
= Required for Blue Books
Note - Red Books are Draft Blue/Magenta Books
Schedule Milestones |  |  |  |  | Original Completion Date
(Date in M/D/YYYY format.) | Comments
(Date in M/D/YYYY format.) | | Project Approved | | | | | 6/7/2019 | | | Project Start Date | | | | | 6/10/2019 | | | Internal WG Review | | | | | | | | First Draft Circulated to WG | | | | | 9/16/2019 | | | First Draft Comments Due | | | | | 10/15/2019 | | | Second draft circulated to WG | | | | | 8/15/2020 | | | Second Draft Comments Due | | | | | 10/15/2020 | | | Final WB Submitted to AD for Further Processing | | | | | 11/15/2020 | | | External Milestones | | | | | | | | Secretariat Document Processing | | | | | 3/15/2021 | | | First Agency Review | | | | | | | | RID Resolution | | | | | | | | Secretariat Document Processing 2 | | | | | | | | Final Agency Review | | | | | | | | RID Resolution | | | | | | | | First Prototype Development | | | | | | | | Second Prototype Development | | | | | | | | CMC Approval | | | | | 8/15/2021 | | Total Time to Complete
(in months) | | | | | 26 | |
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