Nearly fifty years ago, astronomers discovered a bizarre signal in the sky coming from an unknown, mysterious object. Where most astrophysical objects send a steady stream of particles, light and radio waves, this new object was rapidly pulsing x-rays. 

These objects were eventually found to be very compact objects, known as neutron stars. When a star reaches the end of its life, and has exhausted its supply of nuclear fuel, it will expel its outer layers and the core will collapse into a small, dense remnant. If the star was heavy, then there is enough mass that the force of gravity will overcome all resistance and crush the remnant into a black hole. However for lighter stars there simply is not enough matter and enough gravitational force to overcome the nuclear forces that atomic nuclei exert on each other. The collapse stops, and what remains is a effectively a single, large nucleus with a mass comparable to a star. This object is called a neutron star.

The surface of a neutron star remains an active and violent region. The interactions of the nuclei with each other and with other particles create beams of x-rays. When the neutron star is spinning rapidly, as they often do when the initial star was rotating, they send these beams of x-rays across the galaxy and act like a cosmic lighthouse. This pulsing nature earned them the name pulsars.

Now for the first time, NASA intends to launch a probe that will study pulsars in more detail. The Neutron Star Interior Composition Explorer will be launched on a Falcon 9 rocket that is being used to deliver supplies to the International Space Station. It will then be installed as an external payload, and approximately one week later it will begin collecting data from the known neutron stars in the galaxy, focusing on the pulsars.

With a bit of luck, the team behind the NICER mission should be able to quickly collect and analyze a significant amount of data on these mysterious objects. And since the properties of neutron stars can be affected by many other phenomena, including high energy theories such as exotic particles, supersymmetry, and even hidden dimensions of spacetime, this data will have significance for a wide range of physical theories. 

For now the physics community can only watch and wait, and imagine what great new discoveries the NICER mission will reveal!