What is the biggest, by the means of satellite amount, satellite constellation in space right now?

  • $\begingroup$ Please think out the question's clarity: "by satellite amount" ... what do you mean, of mass, or numbers of very small items? The total "constellation" mass of flock3p is less than 500kg. The mass of a single Iridium 1st generation satellite > 600kg which is greater than the whole total flock 3p mass. Then multiply by 98 launched, most still in orbit. Or... constellation of the ISS, 1 off, but amount (i.e. mass) > 400 tonnes. $\endgroup$ – Puffin Mar 23 '17 at 0:11

Planet Labs' Flock 3p, a constellation of 88 Dove satellites, was recently launched aboard ISRO's PSLV-C37, the record-breaking launch of 104 satellites. Wikipedia says:

They head to a morning crossing time, sun-synchronous orbit (SSO) at an approximate altitude of 500 kilometres (310 mi).

According to the Wikipedia Planet Labs article, Flock 3p is the largest fleet of satellites to be launched in history.

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    $\begingroup$ The question is "constellation in space", not "fleet launched". Is Flock 3p a separate constellation from the other doves already deployed? They are not all orbit in a coordinated way? The following link is singular, not plural, but I don't know if that's necessarily indicative: en.wikipedia.org/wiki/Planet_Labs#Satellite_constellation Still, if the different "flocks" are deployed in a coordinated way, or spread out to improve coverage, wouldn't all flocks together represent a single constellation? $\endgroup$ – uhoh Mar 22 '17 at 22:34
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    $\begingroup$ @uhoh The Flock 1 fleet was considered a single constellation: nasa.gov/mission_pages/station/research/news/flock_1. I don't know if the other flocks were intended to join the same constellation or not. My guess is not, but if they are it is still certainly the largest constellation. $\endgroup$ – called2voyage Mar 23 '17 at 1:17
  • $\begingroup$ I can imagine the first flock was a pilot study as Planet Labs worked out how to manage and coordinate a group of satellites, and learned more about the hardware in space. I'll check the TLEs and see what's going on. $\endgroup$ – uhoh Mar 23 '17 at 3:30
  • $\begingroup$ I guess the problem is with the concept of constellation; it's usually understood as a set of satellites in specific rigidly defined orbits relative to each other. But once the number of satellites approaches a hundred, a stochastic approach becomes increasingly practical: have lots of satellites in semi-random orbits and the chance one is in optimal place at the right time is likely better than in case of traditional approach. Instead of 4 satellites taken to precise location, and equipped with fancy station keeping, launch 40 and just let them drift roughly where you want them. $\endgroup$ – SF. Mar 23 '17 at 18:01
  • $\begingroup$ Planet does perform stationkeeping within the orbital plane. See arxiv.org/abs/1509.03270 $\endgroup$ – pericynthion Mar 25 '17 at 4:41

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