text: However, people shouldn't fully depend on cell phones because they are not reliable, and the trusty solution for the difficult situation is OnStar. OnStar is a service that in case of accident or an emergency will contact you. If you are not able to answer, they will contact police department, hospital and fire service giving them your exact GPS location. Therefore, nowadays cell phones are unnecessary devices because they are unreliable in emergency situations while On Star is always prepare to help you in an accident.   Venus is the hottest planet in our solar sytem. It could also be one of the most dangerous planets too. In "The Challenge of Exploring Venus" the author thinks its a good idea to strive furter into exploring Venus even with the dangers the planet contains.