If Earth sciences is in fact cut from NASA, many scientist, engineers, secretaries, janitors, grants office personal, graduate students, professors, ect. would loose their jobs, or in the case of professors, their summer salary. This would not just affect scientist at NASA but also those who fund their research from NASA grants, and their institutions which typically take a 50% cut or overhead from these NASA grants to help run their facilities. NASA is one of the larger grant funding agencies in the US which means that it helps to fund research outside of NASA - quiet literally funding their competition. This is something that hasn't been talked much about within the national conversation. NASA does a ton of cool science itself, but it helps fund so much more cool science throughout the country, in all 50 states. And I bet you there is Earth science done in all 50 states that has been funded by NASA.
This then gets extended even further when you consider NASA's open science policies. All missions which are funded by NASA must have their data made publicly available within a certain amount of time. This time is a little bit flexible, almost always less than a year, as it can take a lot of time to calibrate the data and process it into a useable format - think of it as a form of quality control. This way NASA can assure other, non mission, scientist that the data is in fact "good". For instance, our balloon data from BARREL is on NASA. If you notice, not all of it is up there quiet yet, and it did take us awhile to get the first two campaigns up there as well. This was for a couple of reasons, 1) there are very few of us on the project and we needed to make sure that we were ready for the subsequent campaigns, so processing the data was not the first (or second) thing on the priority list. 2) We need to apply careful calibrations for not just the altitude the balloons were flying at, but the temperature, and lab tests which insure that as the crystal's age, their properties haven't changed... i.e. the crystal is still in good shape so we can trust the measurements. In an attempt to make sure that the data is available quickly to anyone who needs it, we host the preliminary data on our own website which anyone can have access to as well. Many NASA missions do this. That way you know that what is up on CDA web is the most tested version, and the version that mission scientist have the most confidence in. (granted it's always best to contact the mission team so that they can help you and let you know about any oddities with the data)
But how does all this help extend NASA's reach? This data is available to anyone. When I was doing my PhD in Australia I had access to this data. When a researcher at NOAA needs to try to understand an event, they can go get any data they many need from a NASA mission there, no charge and no questions asked. When a researcher at the European Space Agency needs more data coverage, they have access to NASA data, no charge and no questions asked. When High school students or undergrads, or a citizen scientist want to research something, they can get the data at no charge and no questions asked. If a company wants to use this data without having to put up their own satellite, and telemeter down the data and don't want to have to pay for someone then to process the data, they can get this data free of charge and no questions asked. This may not be the best "business plan", but what it does mean is that all citizens (and more) have free access to the data and research that their tax money helped fund. It also means that we have the free flow of knowledge which helps science advance faster - the primary goal of scientist: the pursuit of knowledge and understanding. It costs a lot of money to build an instrument, put it on a satellite and launch it into space making sure the orbits don't collide with anything else up there, or in the ground often in remote locations, collect the data, then process the data into a useable format, store the data for all people to use now and in the future, and keep up the infrastructure to continue to do this well into the future. This is a cost which many do not and can not take on. It is one of the major reasons we have some of the most successful researchers in the world!
So I'll get off my soap box and just recap it all into two points:
1) NASA funds not just themselves, but their competitors through their grants program, meaning that they are a very large job creator.
2) NASA's open data and research policies mean that anyone, any corporation, or any research group benefits from them collecting data and has free access to use this data for their own research/needs.
But others have differing opinions on why NASA should continue to do Earth Sciences. I also agree with the points made by James Dyke, the author of the conversation piece below. But the point remains, NASA should continue to do Earth science research!