[jeffreyH (OP)]

If we detonate an explosive on earth it generates a shockwave through the medium it is situated in. What about an explosion in space? Is it possible to detect a shockwave?

[Colin2B]

The pressure wave you get from compressed atmosphere, which is majority of the shockwave, would be absent. Any vaporised bomb material or gas produced would fly outwards at very high speed but would dissipate very quickly.
You would still get the radiated flash heat and in case of nuclear there would be hard radiation.

[alancalverd]

A shockwave is formed by compressing a gas. There being no gas, there are no shockwaves in space.

An explosive may generate a rapidly expanding ball of gas, but then it has created a transient local atmosphere within which you might generate shockwaves until it disperses. 

[chris]

There is about 1 atom per cubic metre, which is not much to convey the pressure wave which corresponds to a shockwave here on the Earth's surface. But sound would still travel - just very quietly...

[Janus]

There is about 1 atom per cubic metre, which is not much to convey the pressure wave which corresponds to a shockwave here on the Earth's surface. But sound would still travel - just very quietly...

  It depends on the wavelength of the sound compared to the mean free path( how far a particle will travel on average before encountering another) of the particles of the medium.  in order to carry sound, the mean free path must be small compared to the wavelength of the compression wave.  The mean free path where the particles are 1 to the cubic meter is huge. ( a particle could travel for a distance of kilometers before bumping into another particle.)

[evan_au]

Space is a big place...

Shockwaves happen in the atmosphere of the Sun, with magnetic reconnections causing occasional Coronal Mass Ejections. It is thought that there is a more continual process which accounts for the fact that the Sun's surface has a temperature around 5000K, but regions of the corona (farther out) have temperatures as high as 1 million K. This could be due to shockwaves dissipating in the tenuous corona (or perhaps due to electromagnetic heating).

Shockwaves happen where the Sun's Solar Wind hits the gas of interstellar space. This is a turbulent region, which is why NASA had several on/off announcements of their spacecraft reaching interstellar space.

Shockwaves happen where the infalling gas of a collapsing star (traveling at relativistic speeds) hits the relatively solid core of neutronium, resulting in a shock wave propagating outward to form the basis of a supernova. Not to mention when the outer atmosphere of the supernova hits the slower-moving gas around the supernova.

And hypersonic jets from the black hole at the center of a galaxy are seen to punch holes in the intergalactic medium (which is a very good vacuum).