Mr. Weir, you've done it again. You've written another great science fiction book built on real science. Such a great story! The disaster that you have created for earth to overcome was masterful and fascinating. The alien species that you imagined is credible. The fact that your alien was cooperative and interesting instead of frightening, gives me some faith that our real future contact may be positive and beneficial. Your writing is intricate and your descriptions are fascinating. As a former professional engineer, I find your scientific descriptions very satisfying and your imagined new technology interestingly plausible. I'm looking forward to reading it again. Please keep writing. I look forward to your next book with great anticipation.