Yesterday's Kin by Nancy Kress

May contain spoilers.
The worst element of Aliens landing on our Earth would be their intent of good or evil. Not everyone views good and evil as absolute, and in the beginning, the intentions of the aliens in this book are difficult to decipher.
The aliens, that land on our world, aren't complete strangers--they are part of our ancestors that somehow broke off and moved to a distant planet far, far away.
They tell a tale of a spore cloud coming our way within one Earth year, and will hit their planet within twenty-five years. The spores are deadly to the aliens and subsequently deadly to humans.
The aliens set up labs with all the top scientist of the world to find a cure for humans and the quasi-humans also.
One aspect of the story that I consider appealing portrays the primary character who's a middle-aged woman. She's a scientist at a leading university with three grown children. She doesn't have a man and doesn't seem to be looking for one. She threw out her alcoholic husband years earlier, and she concentrates on her work and occasionally her grown children.
Books rarely show a woman, moving up in years, worth anyone's scrutiny in this age of youth and beauty, so this is an immense credit to the writer.
As time moves on she becomes depressed when thinking back on the mother that worked too much, and the mother that couldn't find the secret formula to give her children what they needed.
As the book moves on, her regrets become  perceptible, which leads her down the path of anger, bitterness and regret. I recognize this woman since I have felt these same feelings towards my children, and I've spent copious amounts of sleepless nights contemplating my own maternal defects.
I wish in the end that she lost her frustratingly fatalistic perspective, and after learning a large percentage of the population on our planet will live, including her other two children and grandchild (left on earth), that she would have grasped onto happiness for the human race. Maybe, as time moves on and the pain of her loss diminishes, she will find the ample hope that she needs in her life.