Space blog - Spacecraft operations

UK-DMC-1 to take well-earned retirement

nospam@example.com (Robin Wolstenholme) — Fri, 25 Nov 2011 12:00:08 +0000

UK- DMC- 1, one of the first generation Disaster Monitoring Constellation satellites, is to be retired from service after over 8 years in orbit. UK-DMC-1, was launched on 27th September 2003 with fellow Constellation satellites NigeriaSat-1 and BILSAT-1 from the Plesetsk Cosmodrome on board a Kosmos 3-M rocket. It has exceeded its original 5-year design lifetime by over 50% with an impressive 8 years and 1 month of operation. UK-DMC-1’s imaging workload has now passed to UK-DMC2 and the new generation of DMC satellites, providing data continuity for DMCii’s customers.

UK-DMC-1 was part of the first-ever microsatellite Earth Observation constellation, which introduced remarkable EO abilities for both national and international benefit. The constellation is the work of a pioneering international co-operation consortium led by SSTL and made up of six countries: Algeria, China, Nigeria, Turkey, Spain and the United Kingdom.

In addition to UK-DMC-1’s remote sensing capability, the SSTL100 based satellite also carried several experimental payloads that have proved groundbreaking in themselves. The Cisco router in Low Earth Orbit (CLEO) was a joint project between NASA Glenn Research Center, SSTL and Cisco Systems. It tested delay-tolerant networking in space and led the way for developments towards an interplanetary Internet system.

The GPS Reflectometry experiment on UK-DMC-1 was the first dedicated experiment to demonstrate the viability of using reflected GPS signals from space to measure geophysical parameters, such as ocean weather. For the first time, spaceborne signals were received by the satellite from reflections off sea, ice, snow and land and a follow-on instrument will be flying on TechDemoSat-1. UK-DMC-1’s Resistojet technology was also the first of its kind. This water-based propulsion system proved to be both an efficient and low cost alternative to the use of hazardous propellants which require infrastructure and can cause complications at high pressures.

UK-DMC-1 retired gracefully; like all recent SSTL missions it was prepared for its ‘End of Mission’ as a precautionary measure to minimize space debris. This process began in September 2010 and involved using up its remaining propellant to passivate the satellite, and also lowering the orbit to reduce its remaining time in space before burning up in the Earth’s atmosphere. When this work was completed the satellite continued to be fully operational, continuing to relay image data down to SSTL’s groundstation.

Why retire now? Well, the satellite’s battery ages over the mission lifetime and has now reached a point, well beyond its original mission design life, where it is unable to provide enough power to support full payload operations. With this in mind, the SSTL Spacecraft Operations Team have suspended the UK-DMC-1 workload, and the satellite is now only monitored periodically from SSTL Mission Control in Guildford.

The road to commissioning NigeriaSat-2 in Abuja

nospam@example.com (Robin Wolstenholme) — Mon, 15 Aug 2011 10:19:34 +0100

With launch preparations complete, we take a closer look at how the satellite will be commissioned for its future mission. NigeriaSat-2 will be operated by a team of trained NASRDA operations engineers from the recently upgraded ground station in Abuja.

As part of their latest training and development programme, five NASRDA engineers undertook operations training, which will enable them to task, download and process image data, as well as manage day to day satellite operations.

Nigerian engineers in Guildford

For the LEOP (Launch and Early Operations) phase, four SSTL engineers will join the Nigeria operations team in Abuja. LEOP is expected to cover a period of around one week, during which time the satellite will be stablized. Over the following few weeks, engineers will switch on and test each of the spacecraft modules, including the imaging system. This will be an exciting time when we’ll see the first images and operations are handed over to the Nigerian team.

N2 Ground Segment - with 3.7m S band (left) and 7.3m S/X band Antennas.

A period of calibration will commence over 2-3 months before the Nigerian team begin downloading and processing targeted images, which will be used to help manage urban planning, deforestation, water and food resources and support emergency relief campaigns through the Disaster Monitoring Constellation. NigeriaSat-2 image data will also be made available commercially, supporting a sustainable space industry for Nigeria.

Spacecraft operations

nospam@example.com (Robin Wolstenholme) — Wed, 27 Jul 2011 15:08:04 +0100

When a satellite passes within range of one of SSTL’s ground stations, log files from its entire orbit are automatically downloaded to Mission Control as well as real time telemetry. This “whole orbit data” includes information on the status of the various systems that make up the satellite. The Control Centre computers monitor the live telemetry and alert an operator if there is a problem. Depending on the severity of the problem, the operator on duty is sent an alert by email and SMS if urgent attention is required. During the day, an SSTL team is always on hand, but if a problem should occur out of hours the emergency response team take it in turns to respond.

James Northam, head of the Ground Systems Group, explains: “ We use the whole orbit data to monitor the performance of specific system parameters whilst the satellite is out of range of the ground stations. If there is a problem we can replay the recorded data to help determine the issue.” All the data is archived so there is a record of the whole mission from when a satellite was first launched to the mission completion. “Having this data record is invaluable. “ says James. “It allows us to look at trends in performance and spot the start of an issue early before it becomes a serious problem.”

The ground stations themselves are also monitored and controlled remotely from Mission Control. From a screen in Mission Control, the operators can check the status of all the groundstations and their associated hardware, and see the dish antennas via CCTV to confirm they are operating as they should. This morning we can see an antenna moving into position to track GIOVE-A on the monitor as it happens, making the experience all the more “real”. Like Mission Control, each groundstation is also highly automated: For example, the antenna dish will be stowed automatically in the event of high winds – which is essential when a ground station is in a remote or inaccessible location.
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Inside Mission Control Guildford

nospam@example.com (Robin Wolstenholme) — Wed, 06 Jul 2011 15:27:01 +0100

This week, Space Blog visited Mission Control Guildford – from which SSTL monitors and controls more than a dozen small satellites – with James Northam, head of the Ground Systems Group.

We enter the room. All is quiet, apart from the whirr of server fans. Large flat screens display the footprints of the SSTL satellites in orbit. The reason for this rather quiet control room, explains James, is that SSTL Mission Control is a “lights out” operation, taking advantage of the high degree of autonomy on board the satellites and the sophisticated ground software, written in-house and unique to SSTL, to achieve this high degree of automation.

James said: “We currently track 14 satellites from our Mission Control Centre in Guildford, that is to say following their path as they orbit the Earth. We can follow their progress on-screen as they orbit and when they come into range of one of our groundstations we can communicate with them and gather data – for example monitoring their health or recovering data from the payload.

“In addition to tracking these satellites we also control four of these satellites directly from Mission Control Guildford on behalf of our customers.”

Inside the groundstation

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Introducing the Ground Systems Group

nospam@example.com (Robin Wolstenholme) — Wed, 08 Jun 2011 09:28:09 +0100

This week Space Blog caught up with James Northam, head of the Ground Systems Group to find out more about how SSTL helps its customers to use and control their satellites once they are in space.

James explained, “The moment a satellite is launched into orbit it is physically completely inaccessible, so to make use of the satellite you need a communication link with the control centre back on Earth and tools that enable you to effectively utilise the mission. My Group provides all the hardware and software necessary to do this’

Sapphire (MDA Canada) Ground Station Antenna

The Ground Systems Group comprises four teams: Ground segments, Ground software, Simulators and Spacecraft operations. Over the coming weeks we will find out more about each of these important functions and the technology involved. This week we take a closer look at Ground Segments.

Ground Segments

An SSTL Mission typically comprises two parts - The space segment consisting of the satellite platform and its payload and back on earth, the ground segment. For a typical SSTL mission the Ground Segment comprises a Spacecraft Operations Centre (SOC) which is responsible for the command and control of the satellite, a Mission Operations Centre (MOC) which deals with the payload planning activities and the processing of the payload data and a Ground Station which provides the communication link between the Ground Segment and Space Segment.

The teams involvement is flexible depending on the needs of the customer – “we can provide everything from hardware to integrate into an existing customers ground segment to providing a full turnkey ground segment solution for an SSTL mission”

“Our involvement starts at the beginning of the mission to understand the requirements both from the mission and from the customer perspective. We can then design the Ground Segment based on these requirements and on what, if any, existing infrastructure they may already have.”

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