Global Ground Station Network: A Concept Study

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Global Ground Station Network A Concept Study

• Chris Saunders
• A Presentation to the Spaceops 2002 Conference
• 11th October 2002

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Contents

• 1 Introduction
• Philosophy behind the concept
• 2 Political aspects
• International
• National and commercial
• 3 Financial aspects
• 4 Technical challenges
• Scheduling
• Network integration
• 5 Future possibilities

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Introduction

• Section 1

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The Global Ground Station Network Concept
1. Introduction

• The current situation
• Spacecraft operators need a way to talk to their
  spacecraft this means that they either
• Invest in their own ground segment
• Or, initiate lengthy pre-service negotiations
  with other service providers
• However this can mean
• Ad-hoc data gateways between different
  organisations
• Lack of flexibility in mission operations
• Less than optimum utilisation of assets

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Imagine...
Global real-time service provision to spacecraft
operators
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The Global Ground Station Network Concept
1. Introduction

• An analogy with long distance telephone calls
• A few decades ago, long distance calls were
  pre-booked
• Now, we just pick up the phone and dial
• Similar connectivity envisaged for the GGSN
• Fire and forget applications for link sessions
• Use of any available and appropriate ground
  station
• Complete end-to-end service

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Political Aspects

• Section 2

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We might put machines into space, but it is
still human beings that make the decisions.
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International Politics
2. Political Aspects

• As the name suggests the GGSN would be an
  international initiative
• Governmental and pan-governmental bodies
• NASA, NASDA, ESA etc.
• International commercial organisations
• INMARSAT, EUMETSAT etc.
• Military
• Nato
• Many countries see space hardware as a national
  asset

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International Politics
2. Political Aspects

• Three possible options
• United nations model
• One large global entity controls all space
  operations
• Profit sharing scenario
• Facilities still owned by individuals, but
  antenna time leased to GGSN. Would still need a
  global body to control scheduling etc.
• Spot market model
• Slower evolutionary approach

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Hands off my ground station!
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National and Commercial Collaboration
2. Political Aspects
If the GGSN idea is to be successful, major
space faring nations and organisations, must
work together with open and trustful
relationships.

• This will require dynamic levels of cross
  support
• Lowly coupled - minimum of cross support,
  limited to hardware such as antennas
• Medium coupled - data networks begin to link
  together, but documented service levels are
  agreed prior to operations
• Strongly coupled - complete network
  interaction, with synergy of network management

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Financial Aspects

• Section 3

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Paying for the GGSN
3. Financial Aspects

• The GGSN must offer a standardised interface, not
  only for input of technical data but also for
  billing and negotiation of service level
  agreements
• This billing centre would thus introduce an
  additional layer into the customer-supplier
  relationship, which would need to be paid for by
  the customer
• However additional costs would hopefully be
  mitigated through economies of scale

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Paying for the GGSN - Operator Finances
3. Financial Aspects

• Centralised body negotiates access time with all
  the participating ground segments, and then sells
  this time to individual satellite operators.

• Different mission types will require different
  payment plans
• Within each mission type could have different
  service levels for individual mission
  requirements
• Price charged is inexplicably linked to
  efficiency of scheduling system

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Paying for the GGSN - Provider Finances
3. Financial Aspects

• The GGSN must not monopolise anyones customer
  base. It cannot impose itself on either service
  providers or users.
• Two basic methods of paying for the ground
  segment

• Fixed Fee - use of resources of a particular
  ground segment for certain percentage of time
  (likely lt100)
• Payment for time used - Probably better option in
  early stages. Later move to fixed fee

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Technical Aspects

• Section 4

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The technical challenges will be large, but
probably not insurmountable. The key enabling
technologies are either already available, or are
in development.
Courtesy of NASA/JPL/Caltech
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Standardisation of Mission Control Centre /
Ground Station interface
Extension to CCSDS Space Link Extension (SLE)
protocols. Combined with other CCSDS protocols
will hopefully provide a seamless link
spacecraft ? ground station ? useror,user ?
ground station ? spacecraft
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GGSN Scheduling
4. Technical Aspects
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The DSN 26m Sub-net A Case Study
4. Technical Aspects

• Parts of the DSN are rapidly becoming over
  subscribed with missions - need an efficient way
  of maximising dish usage
• The DSN sub-net of 26m dishes in australia,
  spain and the USA was used by NASA JPL for a
  adaptive heuristic scheduling study
• 3 antennas over a period of only 1 week,
  generate
• 700 variables
• 1300 constraints
• Significant computational power is required!

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The DSN 26m Sub-net A Case Study
4. Technical Aspects

• The problem
• Heuristics have to be manually developed
• Complex interactions between control points in
  algorithms make it hard to create efficient
  strategies
• The solution
• Use adaptive learning processes
• Scheduler uses a set of training problems to
  learn the best strategy (heuristics)
• Then apply these to new data

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4. Technical Aspects
The DSN 26m Sub-net A Case Study
Given 5 minutes of processing time, the results
are...
Average solution time for each scheduling problem
was halved
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Solution rate (i.e. the number of scheduling
problems actually solved) increased by 16
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Given an extra hour of processing time, only an
extra 12 of problems were solved. Adaptive
process focuses very quickly.
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Courtesy of NASA/JPL/Caltech
Courtesy of NASA/JPL/Caltech
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Future Possibilities

• Section 5

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New Futures in Space Exploration?
5. Future Possibilities

• Spacecraft emergency notification beacon (SENB)
• When spacecraft anomaly occurs, need a swift
  response
• Spacecraft could carry a standardised emergency
  transmitter
• The GGSN could provide global monitoring,
  notification and response service

We are approaching a stage, whereby spacecraft
will autonomously and intelligently execute their
missions.
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Long term visionA Solar System wide,
interplanetary Internet, for science and
exploration. Anchored by RF chain to the Earth
(GGSN). 1 Terabyte of data per day by 2015?
Courtesy of NASA/JPL/Caltech
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Conclusions

• Section 6

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It Is Hoped That a Viable GGSN Would...
6. Conclusions

• Maximise utilisation of assets
• Enable better planning of future investment
• Secure greater returns from space missions
• Make interplanetary communications more viable
• Encourage greater co-operation

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