# Presentation: 837282

## mESEM(miniaturized Environmental Scanning Electron Microscope)

**mESEM****(**_**m**_**iniaturized **_**E**_**nvironmental **_**S**_**canning **_**E**_**lectron **_**M**_**icroscope)**

- 2005 Marshall NASA Academy
- Final Project Presentation
**by Michael Lamberty**
- under supervision of
- Brian Ramsey and Jessica Gaskin
- August 12, 2005

## Objectives

- Develop a feed mechanism and sample chamber for a mESEM that:
- 	●	loads samples (rocks, soil)
- 	●	feeds samples to mESEM proper
- 	●	expels samples after imaging
- 	●	maintains vacuum
- 	●	minimizes contamination
- 	●	minimizes cross-contamination

## SEMs 101

_**SEMs 101**_

- 1  vacuum pump
- 2  electron gun
- 3  column
- 4  sample chamber
- 5  detectors

- Operation
- An SEM is a specialized particle accelerator.  It fires a beam of electrons at a sample.  Energy emitted from the sample provides data on its composition and structure.

## Why Send A mESEM to Mars?

- Analyze rocks and minerals
- ●	characterize structure and chemical composition
- ●	determine conditions at and after formation
- ●	evaluate *in situ *resource potential

- Astrobiology
- ●	image micro-fossils     in Martian rocks
- ●	current instruments     lack sufficient resolution

## Martian Environmental Conditions

| Property | Values | Comments |
| --- | --- | --- |
| surface composition | SiO2 44% to 50%Fe2O3 15% to 20%CaO 6% to 7%MgO 5% to 8%SO3 4% to 10% | ● abrasive
● may be corrosive
● large uncertainty
● data only from a few   isolated locations |
| regolith grain size | ~ 40 μm or less | ● poorly characterized |
| windblown grain size | 0.2 to 10 μm | ● poorly characterized |
| temperature | average (-63 °C)range (-89 to -31 °C) |  |
| wind | 2-10 m/s summer5-10 m/s fall17-30 m/s dust storms | ● contamination factor
● vibration factor
● low structural risk |

## Sample Chamber/Feeder Design

- 1	cleaning chambers
- 2	sample inlet lock
- 3	web supply roll
- 4	carrier web
- 5	guide rollers
- 6	sample pocket
- 7	sample
- 8	electron gun
- 9	column assembly
- 10	detectors
- 11	drive rollers
- 12	web cutter
- 13	sample outlet lock
- 14	vacuum chamber
- 15	vacuum pump

- ●	disposable sample pockets
- ●	continuous web
- ●	integrated vacuum chamber

## Proof-of-Concept Model

- web start

- web end

**A**

**A**

**D**

**C**

**B**

**B**

**D**

**C**

**B**

**B**

**F**

- A	web supply roll
- 	2-ply 1-mil polyimide web
- B	guide rollers
- 	split to pass pockets
- C	lower drive roller
- 	split to pass pockets
- 	(no drive shown)
- D	upper drive roller
- E	sample pocket
- F	drive roller bias
- 	biases drive rollers 	together to grip web

**E**

## Feeder Operation (1 of 2)

- feeder on standby

- pocket unrolled

- pocket close-up

- pocket ready for sample

**◄**

- Notes:		A - sample cleaner location		B - mESEM column location

**A**

**B**

**A**

**B**

**A**

**B**

**A**

**▲**

## Feeder Operation (2 of 2)

_**Feeder Operation (2 of 2)**_

- sample in pocket

- pocket close-up

- sample and pocket expelled

- sample ready for mESEM imaging

- Notes:		A - sample cleaner location		B - mESEM column location

**A**

**A**

**B**

**A**

**B**

**A**

**▲**

**▲**

**►**

**B**

## Conclusions

_**Conclusions**_

- Design concept validated
- ●	concept demonstrated to be useful
- ●	webs and sample pockets constructed
- ●	model advanced webs, fed samples, expelled samples
- Further development
- ●	construct scale mechanical model
- ●	integrate with mESEM electronics
- ●	simulate Mars operation
- ●	develop cleaning process
- ●	evaluate sealed sample pockets

## Questions?