# Presentation: 487691

## Materials Science in Space

- A thermal test facility used during the Apollo program as part of the “Project Fire” study where NASA scientists simulated the high temperatures of re-entry and tested materials to understand their thermal properties.
- Photo Credit: NASA

*Advanced Space Academy*

**Notes:**
NASA Academy material, contact information:
Brian Dolan, bwdolan@wisc.edu, 608-513-3672

Ask the campers what happens when they put a match to something like paper. Now think of a million matches being held up to something for a few minutes. This is similar to spacecraft re-entry.

## What is Materials Science?

- Materials science is the study of anything and everything that is made today, from creating new materials to improving current materials.
- Materials science is one of the key research areas at NASA’s Marshall Space Flight Center right here in Huntsville.
- Understanding and creating new materials is essential to going back to the moon, Mars and beyond.

- Creating steel parts from molten steel seen above is just one area material scientists focus on.

**Notes:**
Talk about how, without materials science, all other engineering and construction related to space wouldn’t be possible.

## 4 Types of Materials

- Metals
- Metals are any material that conducts electricity easily. They have a high density, are ductile and malleable, usually have a high melting point, and are usually hard.
- Ceramics
- Ceramics are all in-organic and non-metallic materials. They are strong but brittle and have higher temperature resistance then metals.
- Composites
- Composites are two joined engineering materials done to increase strength. Fibers are embedded in another component material to create a composite.
- Polymers
- Polymers are tiny molecules strung together in long repeating chains and are almost always organic (carbon-based) materials.

**Notes:**
Ask trainees if they can name some of these materials. Examples of ceramics include sand and glass. Most gems are oxides (i.e. ruby is alumina Al2O3) which are ceremics.  Polymers include silly putty, teflon, nylon, polyester, kevlar, and plastics such as soda/pop bottles.

## Metals

- Photo Credit: NASA

- Metals are the workhorse of materials. They are used for structural applications.
- Most metals used in space are alloys. Alloys are the combination of two or more materials, at least one being a metal.

- Alloys have better strength and conductivity then the individual materials do by themselves.
- Brass and steel are common alloys.
- Some alloys used in space and aircraft have combined over ten different elements!
- The shuttle orbiter is constructed of a special aluminum-lithium alloy that is lightweight but strong.

**Notes:**
Directional solidification is when a liquid metal is cooled in only one direction, meaning the mold is drawn out of a furnace that has heaters on 3 sides and can only solidify in one direction, creating extra strength in that direction.

## Metal Alloys & Phase Diagrams

*Metal Alloys & Phase Diagrams*

- Alloys vary according to the amount of each material and the temperature. Material scientists use what are called “phase diagrams” to show these effects. As the percentage of carbon in iron varies, different phases of steel are created which each have their own material properties.

- Photo Credit: ASM Handbook

**Notes:**
The three phases of steel are alpha, (far left), gamma (upper left), and Fe3C (the middle portion). Most steels are alpha or gamma steel which means there’s less than 0.78% carbon found; this is enough to drastically alter the microstructures, increasing strength over only the iron.

## Ceramics

- This is aerogel. It may look like a blue cloud, but it feels like Styrofoam and insulates against heat so well that this blowtorch can’t melt the crayons!

- Photo credit: NASA

- Ceramics are used in space because they won’t melt at high temperatures, such as during re-entry.
- The shuttle tiles and entire thermal protection system is made out of ceramic materials.
- NASA is working on new ceramic materials (such as aerogel) which will be even lighter and will be able to handle even higher temperatures.

**Notes:**
Aerogel is 99.5% air. It is the lightest, has the lowest thermal conductivity, and is the least dense of any material known today. It is silica that is highly porous. It can also support 2000 times it’s weight without collapsing.

## Composites

- This composite has orange fibers which are embedded in a grey matrix material.

- Photo Credit: NASA

- Composites are two or more materials that are processed specifically to increase strength or temperature resistance.
- Placing fibers in one direction into a glue so that the direction of the fibers are aligned can increase the strength by over 100 times!
- The shuttle uses carbon-carbon composites on the leading edges of the wing and the nose cone.

**Notes:**
Composites generally are a ceramic or glass being strewn into a fiber and then placed in a ceremic or polymer.  There are new developments with fibers being placed in metals, called metal-matrix composites, that are looking quite promising and may be used for the CEV.

## Polymers

- These are new polymers that have been developed by NASA specifically for use in space for things like satellite outer foil. They are less effected by radiation and they last up to 10 times longer then the current polymers in space.

- Photo Credit: NASA

- Polymers are everywhere. DNA is a polymer, as are bulletproof (Kevlar) vests!
- They are very lightweight and therefore excellent to be used in space. However, normal polymers are very susceptible to radiation in space.
- Carbon nanotubes are a new polymer that aren’t effected by the radiation in space and could be used for a space elevator or new spacecraft.

**Notes:**
Nanotubes have almost 200 times the theoretical strength of steel. Ask trainees why carbon nanotubes aren’t made today. The answer is making them is very hard to do right now. Material scientists must find a simple way to create them. Right now they are created by burning graphite which creates around 2% C60 soot, or buckyballs, which can be formed into nanotubes.

## ISS Materials Science

- Photo Credit: NASA

- Microgravity causes problems with materials in space that we wouldn’t even think of here on Earth.
- Fire behaves differently in space. Heat doesn’t rise in space because there is no “up”, so the flame is circular.

**Notes:**
Ask the campers what other things might act drastically different in microgravity: water droplets, carbonated beverages (the bubbles won’t rise out of the drink, causing astronauts to get sick).

## ISS Materials Science

- The materials science rack and microgravity glove box are where experiments are carried out in a controlled environment to learn about the freezing of liquid materials in microgravity.
- Soldering is a method of joining metal parts together using a filler metal with a low melting point. It’s a very simple process on Earth, but on the International Space Station (ISS) it is very different.

**Notes:**
Soldering is how all circuit boards are joined today. Find a spare circuit board and pass around to show the solder joints.

## ISS Soldering  – On Ground

- Normal everyday soldering of a circuit board: just apply the iron to the metal, melt it around the joint, and it’s done.

## ISS Soldering– In Space

- Soldering aboard the ISS: the solder metal has a rosin core that helps prevent contaminates from getting into the metal when it is liquid. In reduced gravity, this rosin starts flying around quite violently, which is a potential problem.

**Notes:**
This was done in 2004 aboard the ISS in the maintenance work area. Samples are being returned on STS-114 (Return to Flight) to be analyzed on the ground.

## Future of Space Flight – Repair in Space

- In the future, during long space flight missions, we won’t have the luxury of low Earth orbit (LEO).
- In LEO, we can send broken parts back down to Earth and ship new ones to space in a timely fashion from the rockets and the space shuttle.
- We will not be able to do this so easily on the moon and on Mars.

- Photo Credit: NASA

**Notes:**
Broken circuit boards, wiring, gyroscopes, etc. all are stowed on the ISS. Replacements are delivered aboard one of the flight systems.  NASA cannot do that in for longer missions. A whole new field of space flight repair and fabrication will be developed over the next 10 years in anticipation of living on the moon and traveling to Mars.  

## Future of Space Flight

- Astronauts are going to have to repair and create new parts in space’s microgravity.
- The gravity on Mars is only 1/3 of that of Earth. This is why investigations on the ISS are so important.

- This is a metal cast on Earth. The holes form from air purposely trapped during freezing.

- Photo Credit: NASA

**Notes:**
In space, the bubbles will not rise and escape the liquid metal being cast to creating a sample much like this one. Work is being done on the ISS to understand bubble formation in metals and how they move around in microgravity.

## Materials on Moon & Mars

- NASA is developing processes to use moon dust (called regolith) and Mars dust, which have important materials like iron embedded in it in the form of ceramics.
- The chemical reaction would be       2 Fe2O3  4 Fe + 6 O2. This would create pure iron for structures and oxygen that could be used for life support or rocket propellant.
- On Earth, NASA creates what are called simulants that mimic the surface of the moon and Mars for the purpose of running experiments here on Earth.
- Advances have been made in getting metals out of the regolith for creating magnets, radiation shielding and habitat structures.

- The iron oxide refining process could look like this. Refining the regolith could create moon-based steel and oxygen.

- Photo Credit: NASA

**Notes:**
There are actually over 10 different elements found in regolith; it varies from area to area on the moon and we suspect the same on Mars.  Ideally, after creating the initial moon base, it could be self-sustaining. In fact, regolith is approximately 47% SiO2, so even silicon-based electronics could be fabricated on the moon if necessary. In one of the first “centennial challenges” held by NASA, the MoonRox competition will offer a cash prize of $250,000 to the first team that can extract 5 kg of breathable oxygen from lunar-soil simulant in 8 hours.

## Materials on Moon & Mars

- Radiation is a serious problem in the vacuum of space where there is no magnetic field or atmosphere to disrupt radiation (waves of energy).
- NASA scientists have already created this radiation shielding from a mixture of a polymer and simulant moon regolith.

- Photo Credit: NASA

**Notes:**
The radiation given off by the Sun is either deflected away from the Earth by its magnetic fields as shown above, or absorbed by the atmosphere. Mars and the moon have no magnetic fields or atmospheres and are therefore not shielded from the solar wind.  All materials must then be shielded from radiation using a combination of materials, with different materials shielding out different types of radiation.

## What Would You Do?

- As future engineers, scientists, and astronauts: What materials and processes do you think are going to be drastically different in space?
- What can we do to those processes to adapt them to the space environment?