New Series Captain Earth by Hiroshi Nakanishi

Captain Earth by Hiroshi Nakanishi began in Weekly Shonen Sunday issue 19. Hiroshi Nakanishi last work was Kidou Senshi Gundam Age​ which seems to suggest that he prefers to do manga adaption of animes.
As some of you may know Captain Earth is an ongoing anime by the acclaimed BONES studio.

The story follows high-school student Daichi Manatsu works for the Globe organization to pilot a giant robot called the Earth Engine Impacter  to protect the Earth from the invading alien force known as the "Kill-T-Gang", from the planet Uranus.
-Wiki

In general,  mangas that are adapted from light novels or animes do not usually so as well as its orignal format. Of course there are a few exceptions, but the last such series in Weekly Shonen Sunday was Sasami-san@Ganbaranai which was a manga series adapted from a light novel.

Sasami-san@Ganbaranai had an awful performance and was eventually transferred to a monthly magazine.

The editors probably decided to ride the wave of popularity that was expected from the anime and increase their sales. Weekly Shonen Sunday has no mecha series in it thus the series could build up popularity and draw in new readers.