Red Signal #3: Liberate Saru's Homeworld
The third red signal brought the Starship Discovery to Kaminar in the sixth episode, "The Sounds of Thunder". For hundreds of years, First Officer Saru's homeworld had been subjugated by the technologically superior Ba'ul. In "An Obol for Charon," the Red Angel had placed the dying sphere in the Discovery's path so that the ship would integrate its 100,000 years of data - Dr. Burnham hoped this would safeguard the data from Control. But proximity to the sphere also triggered Saru's Vahar'ai, the Kelpien process of evolution. Now changed, Saru fought to evolve the Kelpiens to liberate Kaminar from the Ba'ul.
It's not clear exactly what role Saru or the Kelpiens have to play in Michael's endgame plan to defeat Control. As Acting Captain of the Discovery, perhaps the fact that Saru is now free of fear will be vital in the battle against Section 31. It's also possible that the future Michael wanted to ensure that Saru and the Kelpiens achieve their desperately-needed evolution, simply because she loves Saru like family. It's also a longshot but, in the time since the Kelpiens beat the Ba'ul thanks to the Red Angel, Saru's people may have learned enough about the Ba'ul's technology that they can use it to join in the fight against Section 31.
Red Signal #4: Get A Time Crystal
The 4th red signal brought the Discovery to the Klingon planet Boreth in season 2's 12th episode, "Through the Valley of Shadows." The ancient monastery on Boreth has a secret purpose: to protect the time crystals that are native to the planet. Captain Pike traveled alone to the monastery to retrieve a raw time crystal, which is vital to the Discovery's plan to hide the sphere data in the far future to keep it away from Control.
While he was at Boreth, Pike was guided by the albino Klingon Tenavik, who is the son of High Chancellor L'Rell and Voq/Ash Tyler. Tenavik, who was brought to Boreth as an infant a few months prior and is now fully grown thanks to exposure to the time crystals, warned Pike about the price he must pay to take one away from the planet. Pike saw his tragic future (which Dr. Burnham alluded to) - that he will be horribly disfigured by delta rays and, by taking the time crystal anyway, the heroic captain chose to lock himself into that destiny. Still, Pike understood the purpose of the 4th red signal was to secure a raw time crystal and he willingly sacrificed his own future to save the galaxy.
Red Signal #5: Get Po To Charge The Time Crystal
The fifth red signal brought the Discovery to Xahea, which is ruled by Tilly's friend, Me Hani Ika Hali Ka Po. The teenage queen first appeared in the Short Trek episode "Runaway" when she stowed away aboard the Discovery and befriended Tilly. Their warm relationship was instrumental in securing Po's help in powering the time crystal so that the second Red Angel suit built to be worn by Michael Burnham would be able to time travel.
It was clear why the fifth signal led our heroes to Xahea and her queen: Po is a genius inventor who designed an incubator to re-crystalize dilithium - her technical know-how was necessary to build a power source that could charge the Discovery's raw time crystal. Essentially, Po built an incubator that could replicate the energy of a supernova in order to charge the time crystal. Po also built "siege weapons" to help the Discovery and the Enterprise fight Control's fleet - and she may even have volunteered to join her Starfleet friends as they jump to the far future.
There are still two more red signals to be revealed, which will hopefully occur in Star Trek: Discovery's season 2 finale. What role they have to play in Michael Burnham's endgame to save the galaxy - and whether her plan will work - remains to be seen.
Star Trek: Discovery's season 2 finale streams Thursday, April 18 on CBS All-Access and internationally the next day on Netflix.