Explanation:

The world’s smallest spacecrafts dubbed as Sprites ever launched are successfully travelling in low Earth orbit and communicating with systems on Earth.
The six prototypes of Sprites were launched in June 2017 as part of the Breakthrough Starshot project designed to test technologies that would eventually be used for interstellar missions.
They are smallest spacecraft that have managed to establish contact with ground stations.
Sprites have been developed by researchers at Cornell University. Each of the mini Sprite spacecrafts are built on a single 3.5*3.5 centimetre circuit board. They weigh just four grams each.
Breakthrough Starshot is a comprehensive space program launched under the US $100 million Breakthrough Initiatives, announced by Yuri Milner and Stephen Hawking to develop and launch practical interstellar space missions. The program aims to demonstrate proof of concept for light-propelled spacecraft that could fly at 20 per cent of light speed. Its main objective is to send one-gram chips to star systems beyond the solar system in search of extra-terrestrial intelligence.

Note:-Recently Stephen Hawkings passed away that's why it is in news.