EDL

We are involved usually in the part of a space program called the EDL.

EDL stands for:

  • Entry—to work on designing the heat shield
  • Decent—to work on deploying the parachute
  • Landing—to work on retro rockets or inflating the bouncy bag, Boing, boing, boing…

Regulations and Disclosures

Silly as it sounds the United States Government has limits on how much I can say about the technical parts of the projects. What I am allowed or not allowed to say is controlled by International Traffic in Arms Regulations (ITAR). It was decided that this technology has weapon potential even though none of this would work on earth.

Propellant and Parachutes

So broadly speaking we make pyrotechnic devices, which contain gigantic amounts of horsepower that can store solid propellant for long periods of time and then used to inflate items or do work such employing parachutes.

That means we have to figure out how to:

  • – to store propellant all the way to Mars
  • – to fire out a parachute
  • – or blow up a bag

We design, test and implement it all so that the Lander will arrive safely on the surface of Mars.

One of the main issues is sealing the propellant against the vacuum of space so that the vacuum doesn’t sublimate the propellant slowly away into space until there is nothing there. We also have to figure out how to time events out so that happen at the right time.

Landing

We have to deal with a very different environment on Mars. The reason we use a pyrotechnic to deploy the parachute is that the atmosphere is so thin that the parachute would not open properly like it would on Earth.

A naturally released parachute would not open in a short enough timeframe to not get tangled and expand. It would never be able to open. We have to shoot it out fast enough to open but not be torn to shreds.

We also can’t shoot the parachute out so hard that it pushes the spacecraft so hard that the Lander is destroyed. That is a bad end result.

Weighty Concerns

It costs thousand of dollars per pound to launch the Lander. And there is only so many pounds that the launcher can lift. Every pound that is used by the landing systems is pound taken away from the real reason for the mission, the scientific experiments.

So weight is a very big issue and the reason we use exotics material such as titanium. We spend hours doing structural analysis to take out every pound that is not critical to the mission.

You can’t have a recall. Everything need to be done right and will work when expected after months of storage in deep space. If there is a one in a million chance of failure of your part then the mission will fail. There over a million parts in the spacecraft and if one fails than the whole mission fails.