The argument for:
The information that was sent back on the very first mission to the Galilean satellites contained surprising data about how Jupiter’s moons were formed, when they were formed, and what these bodies consist of. Further exploration of these satellites will help complete the picture of these distant bodies. Furthermore, the conditions of the formation of the Galilean moons are important because they could potentially provide models for the growth of the other Jovian planets and their satellites. In the bigger picture, any information that can be gained from further exploration of the Galilean satellites can only increase our understanding of our universe; how it was formed, how life began, and if there are other inhabitable worlds with life outside of our galaxy. The knowledge, in general, that the human race can gain from exploration extraterrestrial regions is vast; determine how life developed in the solar system, where it may have existed, whether extant life forms exist beyond Earth, and in what ways life modifies planetary environments, understand how physical and chemical processes determine the main characteristics of the planets, and their environments, thereby illuminating the workings of the Earth, learn how the Sun's retinue of planets originated and evolved, explore the terrestrial space environment to discover what potential hazards to the Earth may exist, discover how the basic laws of physics and chemistry can lead to the diverse phenomena observed in complex systems.
Another distant yet pressing issue that could be solved by exploring other planets and their satellite systems is the expansion of the human race. Humanity may potentially need more room for life than the Earth has to offer, and research into how to sustain human life in space and on other planets may be essential in the future to ensure the survival of the human race.
The concern that too much money is being spent on the space may be an unfounded one. The high profile that the space program has makes it appear to be more expensive than reality. The amount of money being spent on social needs far outweigh the money spent on space incentives; in 2002, the government spent 44.5 billion dollars on the Education Department as a whole, while NASA’s budget that same year was only $14.9 billion.

 

The argument against:
The benefits of the space exploration are not self-evident, no matter how real they are. Why spend billions of dollars on sending missions into space when there are issues on Earth that need to be addressed, like crime, poverty, the national debt, terrorism, the economy, and the environment? There is a definite concern that money is being wasted in space, and the apprehension deals with the spending priorities of the government. A typical shuttle mission ca cost between $400 million and $500 million, and to complete and launch a satellite could cost around $20 million. With all of this funding required, many missions, such as the Galileo spacecraft, end up crashing into their intended subjects or simply flying out into deep space to become space junk. During the Galileo mission, the radioactive environment caused the gradual degradation of the instruments onboard the spacecraft, and eventually led to their failure.
The cost of the space program is not only paid in money either; the lives of many astronauts are at stake during manned missions. No one can forget the tragedies that occurred with accidents involving the Challenger and the Columbia shuttles, which caused the deaths of fourteen crewmembers in total. Currently, the risks of manned spaceflights are only increasing as budgets are being cut back and safety and quality-assurance programs are trimmed back.