Consultative Committee for Space Data Systems

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The Consultative Committee for Space Data Systems (CCSDS) (German: " Advisory Committee for Data Systems in Space Travel ") based in Washington, DC is an international organization that brings together the leading space organizations. The task of the CCSDS is the development of common methods of data traffic with spacecraft, primarily research probes.

The CCSDS was founded in 1982 at the suggestion of a joint NASA and ESA working group that has been working on common communication protocols since 1981 . An ever-expanding cooperation between the individual space organizations and the necessary mutual use of infrastructures made the definition of common standards imperative.

review

The first Pioneer and Explorer space probes sent their telemetry data as a simple sequence of sinusoidal oscillations, the frequency of which changed proportionally to the measured value, each individual measured value was assigned a time slot , and the first time slot always had a pilot tone for synchronization . This simple time division multiplex process soon no longer met the requirements. The newer procedures and the increasing international cooperation brought about the today's importance of the CCSDS .

SCID - numbering of the spacecraft

Today every spacecraft is assigned its own number assigned by the CCSDS, which is also part of the standardized data blocks that are exchanged between the ground stations and the spacecraft, as well as standardized time and position information. The number of the spacecraft ( SCID - S pace c raft ID entification) have been prepared from the original 8 bits extended (0..255) on two number ranges with 10 bits (0..1023). The version (2 bits) of the number range is placed in front of the number itself. One of the four possible number ranges has not yet been assigned.

The numbers are administered centrally for all space organizations involved at the World Data Center for Satellite Information ( WDC SI ) in NASA's Goddard Space Flight Center (GSFC) in Greenbelt (Maryland).

construction

The actual number is preceded by a grouping of the SCID consisting of two bits as a version number; it defines the number range . 00 = first number range with 10-bit numbers, 01 = number range with 8-bit numbers, 10 = second number range with 10 bits, 11 = not assigned. Both together - version and SCID - form the GSCID (Global Spacecraft Identification).

Examples

  • The Ariane 5 has a uniform number for all rockets, there is always only one rocket in flight for a short time. The 8-bit number 1Ah (0001 1010) is assigned here.
  • The space shuttles have been assigned 10-bit numbers.
OV-103 ( Discovery ) the 1D3h (01 1101 0011)
OV-104 ( Atlantis ) the 1D4h (01 1101 0100)
OV-105 ( Endeavor ) the 1D5h (01 1101 0101)
The numbers for OV-101 ( Enterprise ), which was never designed for space flight, and the crashed OV-99 ( Challenger ) and OV-102 ( Columbia ) are not assigned.

Time formats

In the Blue Book 301.0-B-3 the most different time formats are defined, here the most important:

  • CUC = CCSDS Unsegmented Time Code
  • CDS = CCSDS Day segmented Time Code
  • CCS = CCSDS Calendar segmented Time Code
  • CCS ASCII = CCS in ASCII representation

The CUC format is a pure binary counting format in which a 32-bit unsigned binary number indicates the seconds since a certain point in time. The value can still be followed by fractions of a second as a binary value; various sub-formats are defined for this.

This format can cover about 136 years. There are different starting points - at NASA, January 1, 1958 is common.

The CUC value in the spacecraft is derived directly from the Elapsed Time mission .

The first version of the Blue Book 301.0-B was used in 1987. The third version from 2002 is currently valid, although it is planned to be revised again.

Publications

  • Blue Books - Standards and Requirements
  • Magenta Books - Standing Procedures
  • Green Books - Informal Reports
  • Orange Books - Experimental Specifications
  • Yellow Books - General Reports
  • Silver Books - Obsolete standards, requirements and reports

Most of the publications are available on the Internet as PDF documents.

Organizations involved

There are several ways in which you can work with the organization. There are three levels of rights and duties: members, observers and associates.

Full members

In mid-2017 the organization had 11 full members: Members are state organizations or state-affiliated organizations that make an appropriate contribution to the activities. Only one member at a time can represent a state or a multinational organization. All members must adhere to the resolutions and do their best to implement the resolutions by adapting their own standards to those recommended by the CCSDS. Members must assign delegates to the technical working groups. All members are called upon to present drafts and positions on factual issues in the working groups. The member organizations alone have the right to vote at the two meetings of the year.

observer

In mid-2017 there were 31 observer organizations:

A CCSDS observer is a government or government-affiliated organization that supports the activities of the CCSDS on a lower level. Observer organizations are encouraged to implement the recommended standards, but do not necessarily have to adapt their own standards. Observers can, but do not have to, contribute their own suggestions and positions to the working groups. Delegates from the observer organizations can participate as technical experts. There is no limit to the number of national or multinational organizations that can act as observers.

Associated Organizations

106 associated organizations were registered in mid-2017. Associated organizations are scientific or industrial bodies that make it possible to follow the decision-making process and possibly influence the standards. These are manufacturers who supply products or services for space travel, research institutions and universities.

Associates can participate in working groups and contribute to the development of the standards if a full member or a supporting observer organization expressly agrees. Associates can also submit drafts or position papers through their supporting member or observer organization. In general, the supporter and the commercial associate should come from the same country. Multinational organizations e.g. B. ESA can support associates from any country that has a stake in the supporting organization.

Deep space antenna locations

For the operation of various space missions, the antennas of various agencies were often involved at the same time. For some missions, the use of antennas from another agency is unavoidable. A particularly close cooperation exists between the DSN of NASA and the ESTRACK network of ESA. However, cooperation also takes place between the other agencies on a case-by-case basis on the basis of contracts for individual missions. The cooperation of several agencies on a mission relates not only to the construction of the vehicle, the instruments, the launcher, during take-off and the evaluation of the results, but often also to the operation and communication, which are regulated via CCSDS. There is also an agreement between the agencies for short-term mutual assistance in emergencies. Some antennas have been built for radio astronomy, but are sometimes also used for space missions for the downlink, usually these have no uplink options.

Consultative Committee for Space Data Systems (World)
Kashi
Kashi
Jiamusi
Jiamusi
Kunming
Kunming
Miyun
Miyun
Tian Ma
Tian Ma
Lejano
Lejano
New Norcia
New Norcia
Cebreros
Cebreros
Malargüe
Malargüe
Uchinoura
Uchinoura
Byalalu
Byalalu
Yevpatoria
Yevpatoria
Galjonki (Ussuriysk)
Galjonki (Ussuriysk)
Medvezhi Ozera (Bear Lakes)
Medvezhi Ozera (Bear Lakes)
VLA
VLA
Worldwide deep space stations with antenna diameters of 30 m or more: blue = DSN, green = ESTRACK , red = CDSN , yellow = Jaxa , orange = ISRO , violet = Roskosmos , turquoise = DLR , black = scientific radio telescopes, pink = commercial deep Space Station (from around 2020)

The cooperation also includes the tracking facilities for tracking rocket launches at low altitude and satellite tracking with smaller antennas that are widely scattered around the world and some of which are also operated commercially. These tracking stations with smaller antennas are not shown on the map.

See also

Web links

Individual evidence

  1. ↑ CCSDS.org - Review Documents. Retrieved January 20, 2019 .
  2. ↑ CCSDS.org - Member Agencies. Retrieved August 1, 2017 .
  3. ↑ CCSDS.org - Observer Agencies. Retrieved August 1, 2017 .
  4. ↑ CCSDS.org - Associates. Retrieved August 1, 2017 .