Well, as many of you might know by now, we broke the 3rd Gaia Data release in two pieces, the first of them, EDR3 is now scheduled for December 3 at 12:00 CET
, and the full DR3 release will happen somewhere in 2022 (the date is still unknown).
What should we expect from the December release?
Well, for now at least 100 million additional stars
that DR2 missed (that's a ~6% increase in the amount of stars
). This is funny, we started the mission expecting a billion star survey and now we are slowly reaching 2 billion stars (not only Gaia is performing better than expected but also the Milky Way seems to be more populated than we previously thought).
As you might also know, not all the stars in the previous release (DR2) had parallax and proper motion measurements, in fact it was 78.7% of the sample that had all of them. But now with EDR3 many more have parallax measurements for the first time (thus, geometric distance estimates). In fact around 1.5 billion stars are expected to have the full set of astrometric parameters
(that will be around the 83% of the new release
). So more distances and more completeness inside the catalog.
Another beautiful thing to expect from December's release is the increase in accuracy of the parallaxes and the better disentanglement of the parallax motion with the proper motion (thanks to a longer time since the mission begun). We expect an improvement in the parallax measurements of 20% with respect to Gaia DR2
, that will in turn translate to some improvements in the estimated distances to the stars. The proper motion will be a factor of 2 more precise
(better understanding of the dynamics of the galaxy and the evolution of our stellar neighbourhood).
So, to sum up, the EDR3 will enhance the data of DR2 and add a little more stars to the catalog solidifying what we currently have. But the true next quantum leap (as the one that happened when DR2 was released in 2018) will happen in 2022 with the full DR3 release, when radial velocities will be calculated for a massive number of stars, low resolution spectra will be collected (so we can finally have a consistent way of estimating the classification of hundreths of millions of stars), and brightness variability data for the first time (which will show millions of new binaries, thousands of new exoplanets and hundreths of new Cepheids that in turn will help us to make the distance ladder
stronger and change our knowledge on cosmological scales).
We expect funding for an extended Gaia mission (for now ESA can talk about plans only up to 2022) so we can yield a DR4 and a DR5 in the next decade. This spacecraft is one of the things I think of to make me feel proud of mankind.