"Why spend money on space when we have so many problems on Earth?"

Rift valley fever distribution.

Here's why:

An early warning system, more than a decade in development, successfully predicted the 2006-2007 outbreak of the deadly Rift Valley fever in northeast Africa, according to a new study led by NASA scientists.

Rift Valley fever is unique in that its emergence is closely linked to interannual climate variability. Utilizing that link, researchers including Assaf Anyamba, a geographer and remote sensing scientist with the University of Maryland Baltimore County and NASA's Goddard Space Flight Center in Greenbelt, Md., used a blend of NASA and National Oceanic and Atmospheric Administration measurements of sea surface temperatures, precipitation, and vegetation cover to predict when and where an outbreak would occur.

The final product, a Rift Valley fever "risk map," gave public health officials in East Africa up to six weeks of warning for the 2006-2007 outbreak, enough time to lessen human impact.

and:

As early as September 2006, the monthly advisory from Anyamba and colleagues indicated an elevated risk of Rift Valley fever activity in East Africa. By November, Kenya's government had begun collaborating with non-governmental organizations to implement disease mitigation measures--restricting animal movement, distributing mosquito bed nets, informing the public, and enacting programs to control mosquitoes and vaccinate animals.

Being able to observe the Earth from space makes an especially big difference for countries with small economies that aren't able to mount extensive campaigns to completely eradicate diseases or fight against mosquito and other populations that spread them, so for them being able to pinpoint regions where diseases are likely to strike is of paramount importance in stopping diseases from spreading.

So the question is, how much longer do we have to put up with the myth that one needs to eradicate every single problem here on Earth before heading out into space?