Image courtesy of ESA
Note: The debris field shown in the image is an artist’s impression based on actual data. However, the debris objects are shown at an exaggerated size to make them visible at the scale shown
Reports at the weekend from Roscosmos, Russia’s State Space Corporation, indicated there was a near miss between India’s Cartosat-2F and a Russia’s Kanopus-V satellite last Friday. According to Roscosmos’s Warning Automated System of Hazardous Situations information centre, the satellites came as close as 224 m at the closest point.
However, the Indian Space Research Organisation (ISRO) indicated that the satellites only came within 420 m of each other. ISRO also noted that they had been tracking the satellites for a few days and would have done a manoeuvre if they had come to within 150 m of each other. They said that these close calls are more common that people believe, but generally they are resolve in private between the relevant space agencies. About a year ago we wrote a blog on the close call between ESA’s Aeolus Earth Observation (EO) satellite and one of SpaceX’s Starlink satellites.
Both of the satellites involved here are EO satellites. Cartosat-2F is a high resolution imaging satellite with both multi-spectral and panchromatic images offering a spatial resolution 1 m with a swath of 10cm, and was launched on was launched on the 12th January 2018. Whilst, Kanopus-V is a small remote sensing satellite which also has a both a multi-spectral and panchromatic imager, with the former offering 12 m spatial resolution on 20 km swatch, and the later on 2.5 m spatial resolution with a 20 km swath
Both satellites were orbiting at around 500 km altitude, although it is not known what brought them into such close proximity.  However, it is accepted that the low Earth orbits are the most congested part of space. This situation will not have been improved by the launch last week, 24th November, of the latest 60 Starlink satellites via the SpaceX Falcon 9 rocket. This took the number of Starlink satellites in orbit to just shy of 900, and the company has begun beta tests of its broadband internet service.
The majority of the Starlink satellites operate in non-polar inclined orbits at around 550 km. However, interestingly, earlier this month SpaceX asked permission to start launching satellites into sun-synchronous orbits to allow it to offer its services to rural Alaska.  Fifty-eight satellites will be placed into orbit at 570 km, and will not go higher than 580 km to ensure they don’t interfere with Amazon’s impending Kuiper internet broadband constellation, who’s anticipated 3,200 satellites will go into a 590 km orbit.
Another large scale launcher, OneWeb, last week rose from the ashes of bankruptcy too. The new company is jointly owned by the UK government and the Indian conglomerate Bharti Global Ltd. It already has 74 satellites in orbit and is planning to launch another thirty-six later this month, and has planned to put another 538 into orbit for its broadband constellation. This, of course, was before the bankruptcy and it will be interesting to see if it follows exactly the original path. The UK Government have stated ambitions to try to build a UK GPS on the back on the constellation, although the Indian partner currently, and as expected, seems focussed on the telecommunications side.
In addition to an increased risk of collision, the sheer numbers of satellites going up will have an impact on astronomy as they appear in the night sky as bright white streaks..
The number of satellites in space, and the UK Government’s contribution, is an issue that will continue to develop in the coming years.
