Project Title

Time Management Green Book



Document Number



1.07 Time Management Working Group

Document Type


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.


Book Editor


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



Monitor Only


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.


Legend for Schedule Milestones
Orange Bullet = Required for Orange Books
Green Bullet = Required for Green Books
Magenta Bullet = Required for Magenta Books
Blue Bullet = Required for Blue Books
Note - Red Books are Draft Blue/Magenta Books

Schedule Milestones
Orange BookGreen BookMagenta BookBlue Book
Original Completion Date
(Date in M/D/YYYY format.)
Estimated Completion Date
(Date in M/D/YYYY format.)
Actual Completion Date
(Date in M/D/YYYY format.)
(Date in M/D/YYYY format.)
Project ApprovedOrange BulletGreen BulletMagenta BulletBlue Bullet6/7/20196/7/20199/11/2019
Project Start DateOrange BulletGreen BulletMagenta BulletBlue Bullet6/10/20196/10/20199/11/2019
Internal WG Review
First Draft Circulated to WGOrange BulletGreen BulletMagenta BulletBlue Bullet9/16/20199/16/20195/8/2020
First Draft Comments DueOrange BulletGreen BulletMagenta BulletBlue Bullet10/15/201910/15/20195/29/2020
Second draft circulated to WGOrange BulletGreen BulletMagenta BulletBlue Bullet8/15/20208/15/20206/25/2020
Second Draft Comments DueOrange BulletGreen BulletMagenta BulletBlue Bullet10/15/202010/15/2020
Final WB Submitted to AD for Further ProcessingOrange BulletGreen BulletMagenta BulletBlue Bullet11/15/202011/15/2020
External Milestones
Secretariat Document ProcessingOrange BulletGreen BulletMagenta BulletBlue Bullet3/15/20213/15/2021
First Agency ReviewMagenta BulletBlue Bullet
RID ResolutionMagenta BulletBlue Bullet
Secretariat Document Processing 2Magenta BulletBlue Bullet
Final Agency ReviewMagenta BulletBlue Bullet
RID ResolutionMagenta BulletBlue Bullet
First Prototype DevelopmentBlue Bullet
Second Prototype DevelopmentBlue Bullet
CMC ApprovalOrange BulletGreen BulletMagenta BulletBlue Bullet8/15/20218/15/2021
Total Time to Complete
(in months)
Version: 66.0
Created at 5/24/2019 4:33 PM by Peter Shames
Last modified at 4/16/2024 6:50 PM by Tom Gannett