India’s Cartosat 2F weighing over 700kg dangerously approached the Kanopus-V spacecraft at 1.49 UTC, on Friday, according to the Russian Space Agency. In a tweet, Roscosmos has said that the minimum distance between both Russian and foreign satellite was 224 meters. Both the satellites are meant for earth’s remote sensing.
How significant and dangerous is this? According to a source that spoke to Zee Media on the condition of anonymity, 1 Kilometer is an ideal distance between satellites in orbit, whereas 224 meter is scary and can be counted as a near miss. Generally, when two satellites are predicted (based on calculations) to make a close pass, a decision is taken to manoeuvre one of them away in advance(usually days ahead).
Given how space is getting increasingly crowded with satellites that are used for various purposes, it is said to be normal for agencies to manoeuvre one of their satellites every 3-4 weeks. It is notable that low Earth orbit (500-2000km) is the most congested, with satellites of various sizes – ranging from 10cm cubes to ones that are the size of a car or larger.
However, the decision to manoeuvre is not very easy. Especially, when the satellite is performing a strategic role that requires it to be at a particular spot. Because the manoeuvre would affect the schedule of the pre-planned operation of surveillance (in whatever form).
In this case, Roscosmos has said that both are remote sensing satellites, which implies that they in all likelihood used for strategic purposes.
The space community has been divided over the prediction models for tracking satellites in orbit. The existing ones are the European Model, American model, Russian model, whereas the Indian model is under development. The reason that the space community hotly debates the efficiency of the models is that there are differences between the calculations made using each model.
Let’s assume, in this case, the Indian model said that the satellites would be 1km apart, whereas the Russian model would have predicted that they would be 500m apart.