Flight proven satellite platforms from Surrey Satellite Technology US LLC (SST-US) have been selected by NASA's Rapid Spacecraft Development Office (RSDO) for inclusion in the third NASA Rapid Spacecraft Acquisition Catalog (Rapid III).

SST-US’ Chief Executive Officer, Dr. John Paffett stated

It is a privilege for SST-US to have been selected by NASA for inclusion in the Catalog. It is recognition of the company’s capabilities, expertise and heritage. We believe that the Catalog provides an efficient route for SST-US to provide rapid, low risk, cost effective satellite solutions to NASA and other Government Agencies and we look forward to delivering future mission opportunities.

Through this contractual framework SST-US will be able to engage with NASA and other Government Agencies for the rapid provision of low risk, cost effective satellite solutions based on the SSTL 150, 300 and 600 platforms.

Continue reading "SST-US platforms get NASA seal of approval"

SSTL’s military space expert Dr. Stuart Eves has accepted a year’s secondment to the new Science and Technology Facilities Council (STFC) at the UK’s new Harwell facility to advise on space security. His principal responsibility will be as the authority on the Security and Resilience Unit (SRU) that will form part of the International Space Innovation Centre (ISIC).

Enough with the acronyms! ISIC is a joint venture between the UK Government and Industry, that is anticipated to evolve into a centre which supports both UK national requirements as well as international security-related space systems. The idea is to create a Hub of Innovation that will act as a seed-bed for innovation in the UK.

Stuart will also be expected to actively liaise with the newly formed UK Space Agency on space security matters in support of government policy making, since a close relationship between the policy and strategy aims of the agency and the executive elements at ISIC will clearly be essential.

Continue reading "Space security guru Stuart to advise government"

SSTL’s Optical Payload Group is currently building two Dynamic Multi Star-field Simulators (DMSS) at its Sevenoaks facility that will be used to test star trackers that will be flown in space under simulated operating conditions here on Earth.

Star trackers are an essential subsystem in any satellite, providing information that allows the spacecraft's on board computer to determine its orientation or “pointing” at any point in time.

They work by taking an image of a region of the sky using a specially designed optical camera, and comparing successive images to determine how much the orientation of the satellite has drifted.

This information is then sent to an attitude control system that corrects for the drift by using on-board thrusters or other motion-generating devices to maintain the correct satellite pointing.

Any time a satellite is manoeuvred in orbit, the pointing information from star trackers is vital to the spacecraft’s control systems. For example, solar panels must be aligned to capture the maximum available light from the Sun, and communications antennae pointed towards the Earth.

Star trackers are now available that operate in autonomous modes. These units are able to dynamically monitor the star fields in orbit and provide correction information back to the satellite to counteract adverse platform manoeuvres, such as slews and spins, which is particularly useful in the early stage of mission operations or following a major system failure.

To test these units on the ground prior to launch, it is essential to present the star trackers with a dynamically varying star field. This is where the DMSS comes in.

Continue reading "Simulators prepare star trackers for spaceflight"

This week, an enormous cloud of volcanic ash is sweeping over Northern Europe, grounding aeroplanes and bringing the jet-setters to a standstill. One could be forgiven for taking it all for a hoax – there’s nothing for the common Earth dweller to see – but it’s bringing some businesses to a standstill as they struggle to make their meeting’s commitments.

The reason this ash cloud cannot be seen is that the ash cloud is moving relatively high in the atmosphere, although meteorologists say there are signs some dust is settling at lower levels, which could begin affecting the health of those with respiratory conditions such as asthma. However the risk to aircrafts is very real as reported in the excellent BBC News online article: Icelandic volcanic ash alert grounds UK flights

But what about satellite communications? Could the dust in the atmosphere affect the control of space missions, your Sky receiver or GPS? Pete Garner, SSTL’s Radio Frequency (RF) team leader commented:

Satellite comms could easily be affected, but the impact would depend primarily on weather conditions, which would determine how the volcanic ash is dispersed in the air.

Additionally - it would also depend upon the robustness of the comms links in question. I know personally that my Sky signal degrades or even drops out periodically if there is heavy rain in our area and the volcanic ash could cause similar problems as the density and composition of the ash cloud would reduce the link margin and therefore affect the quality of any transmitted signals.

SSTL tracks and controls many satellites from its Guildford-based ground station, but Pete explained that their systems are designed to cope with environmental factors – even if no-one expects clouds of volcanic ash over the green hills of Surrey:

SSTL ensures its LEO [Low Earth Orbit] comms links are robust enough to cope with heavy rain in most cases by sizing the whole comms system appropriately for the mission including environmental factors. Making sure there is adequate additional margin in the link budget design is a key factor from the early stages of any mission to ensure SSTL can continually control the satellites and obtain the important image data when required.

In some cases there is also a level of redundancy. For example, Earth observation satellites such as Nigeria’s new NigeriaSat-2 satellite that is scheduled for launch in Q4 2010 have the facility to download images to multiple groundstations around the world. Some satellites can also be tracked and controlled from more than one groundstation when required.