Archimedes famously said: Give me a lever long enough and a fulcrum on which to place it, and I shall move the world. Luckily, no such lever or fulcrum has been placed, so our world keeps safely orbiting. This is a case where the physics of the saying is true, but the reality of we humans and our engineering doesn’t allow us to take advantage of that physics.

There are lots of cases like this. For instance, to measure the distance to an object using basic trigonometry, we need to be able to observe that object from two separate positions. Humans use two eyeballs to perceive distances to objects around us. Astronomers use the Earth’s motion around the Sun to get measurements of the distance to nearish stars. Our ability to measure distances is only limited by where we can observe from. Give us two measurements far enough apart, and we could measure the distance to anything in the visible universe.

And this is where the CLEoPATRA mission comes in. Written out, this acronym stands for Contemporaneous LEnsing Parallax and Autonomous TRansient Assay, and the plan is to stick this mission on a ride out toward Mars with a future Mars mission. It will be placed in a solar orbit that will allow it to make coordinated observations with the planned Nancy Grace Roman space telescope to observe objects. Acting as two eyes, this pair of systems will allow researchers who spot rogue planets to figure out their distance. According to mission scientist Richard Barry: The parallax signal should then permit us to calculate quite precise masses for these objects, thereby increasing scientific return.

Now, this story somewhat buries the lede: I said this mission will help measure the distance to rogue planets. These are planets that have been flung out of their star systems at some point in the past and now lurk between the stars. They can be seen when they ever so briefly pass in front of a distant star and gravitationally increase the amount of light we can see. This is only possible for a brief moment in time, and in the past, observations didn’t allow us to measure distances to these objects.

With CLEoPATRA out there, we have that farther apart pair of telescopes that makes measuring greater distances possible.

More Information

NASA Goddard press release