Welcome to GISWeekly! Several developing nations will soon launch micro-satellites for the purpose of gathering low cost, medium resolution multispectral imaging. See this week's Industry News for an interview with James Northam, Senior Design Engineer of Imaging Systems at Surrey Space Centre of the University of Surrey for more details.
GISWeekly examines select top news each week, picks out worthwhile reading from around the web, and special interest items you might not find elsewhere. This issue will feature Industry News, Alliances/Acquisitions, Announcements, New Products, Going on Around the Web, and Calendar.
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Susan Smith, Managing Editor
|Taken by AlSAT-1, a 600x600km image of Western USA illustrates the unique wide-swath imaging capability of the DMC satellites, showing an area stretching from Los Angeles up to the south-eastern region of San Francisco and across Nevada and New Mexico, to Utah and the Grand Canyon.|
Micro-satellites and Remote Sensing
By Susan Smith
Satellites and satellite imagery are definitely in the news this week. With the announcement from The National Imagery and Mapping Agency (NIMA) (see under Awards below Industry News) of the award of a five-year contract to Longmont, Colorado-based DigitalGlobe, Inc., to assure the availability of high-resolution imagery from the next series of U.S. commercial imagery satellites, the U.S. Government confirms its commitment to implementing a strong partnership with the remote-sensing industry. The contract, known as NextView, will potentially award more than $500 million to DigitalGlobe over the five year span and make readily available as part of that commitment 0.5-meter commercial imagery. This looks good for other satellite imaging companies as well.
On the micro-satellite level, a recent article in Wired News, A Big Leap for Small Satellites by Michelle Delio (September 29, 2003), brought my attention to the fact that “several nations are planning to soon launch swarms of autonomous baby satellites that will visually scour the Earth in search of Mother Nature's secrets.” These satellites will provide cheaper technology for space exploration, and many other uses.
I interviewed James Northam BEng (Hons) MIEE, Senior Design Engineer - Imaging Systems at Surrey Space Centre of the University of Surrey, Guildford in Great Britain about the role of the smaller satellites, and what they can offer in the coming years.
|The Turkish DMC spacecraft, BILSAT-1, at the Surrey Space Centre in Guildford|
The benefits are the cost and time. We can design deliver and launch a satellite in around 18 months. A conventional large satellite (1000kg+) can have a conception to orbit time of up to 10 years. Technology moves forward in this time and the cost is enormous - $500M. A typical SSTL mission is around $10M. The satellites also need much smaller ground support infrastructure leading to cost savings in the groundstation implementation. The low mass (typically 100kg for a Micro satellite) means launch costs are lower - multiple satellites on the same launcher for example.
Its limitations are down to its size - it is limited to the payload capacity it can carry, and smaller solar arrays mean less power for payloads and downlinks.
2) What kind of resolution do the images from these satellites provide?
The DMC spacecraft provide 32m GSD in three spectral bands (NIR/ Red / Green), But we have flown imagers capable of 10m Resolution. The China DMC satellite will also carry a 4m high resolution Pan payload.
|A full resolution tile from the large image shows Las Vegas.|
That is true, but ESA recommend that satellites are de-orbited. There is no legislation as such at the moment, but as the amount of satellites increase in orbit, there will be a a push to implement such legislation. Our satellites have small propulsion systems, so its just a matter of keeping a small amount of fuel available for the end of their lifetime, to enable the orbit height to be lowered, the orbit will decay and the satellite will burn up in the atmosphere. We track all our spacecraft, but NORAD track all objects orbiting the planet, so orbits are carefully planned to ensure safety for our satellites and others.
4) Are you contracted by any of the larger remote sensing/satellite imagery companies such as Space Imaging, RADARSAT, etc. to develop satellites for them?
If not, do you see this as a future possibility? Not at present. Our main work has been with developing countries. With the launch of the first DMC spacecraft, Alsat-1 last year, we have demonstrated low cost, medium resolution multispectral imaging from a small satellite it has aroused interest in the remote sensing world. We are continually looking into low cost solutions to remote sensing and are presently developing thermal IR and hyperspectral payloads for future missions.
5) What is the actual price range for the satellites, compared to larger satellites?
Our range of satellites extends from Nano satellites of 10kg mass and $1M up to Mini satellites of 250kg mass and $20M costs. The DMC satellite is based around an enhanced Micro satellite platform - 100kg and $10M cost. Larger satellites can cost from $500M upwards.
|NigeriaSat-1 and UK-DMC undergo thermal vacuum testing at Rutherford Appleton Laboratory in the UK. Photo courtesy of RAL.|
7) What uses do you see for the small satellites besides space exploration?
Apart from communications - i.e. networks of small satellites in orbit and remote sensing, another use is remote inspection. Small spacecraft under 1kg, with imaging and propulsion capabilities, make excellent remote inspection craft, able to inspect other satellites and large objects such as the shuttle, ISS etc.
8) Do you see small satellites usurping the role of larger satellites, or will there simply be a need for both?
Both serve different roles. Large spacecraft can carry larger payloads, but then cost to replace is high. Smaller sats have lower build costs, meaning more can be launched at the same time. Take the DMC - with 4 spacecraft in constellation - we can revisit and image any area within the world in 24hrs. A capability no other Remote sensing spacecraft system has at present. DMC replacements are low cost if there is a failure. With the present lull in the space industry, the low cost approach to small satellites has never been more valid.