# Presentation: 105175

## MAXIM Periscope Module

**Instrument Systems Engineering**
**Deborah Amato**
**25 April 2003**

## A Pair of MAXIM Periscopes

- Detector

- Periscope Module

- 1

- 2

- 3

- 4

## Launch Configuration

**Launch Configuration**

**1 Detector spacecraft**
**26 Periscope spacecraft for 1000 cm****2**** of collecting area:**
- 25 free-flyers with 4 periscopes each
- 1 hub with 12 periscopes

- Free-flyer

- Hub and Detector spacecraft stacked

- Launch fairing envelope

## Operational Configuration at L2

| S/C | Dist from hub (m) |
| --- | --- |
| 1 | 10 |
| 2 | 11.8 |
| 3 | 13.9 |
| 4 | 16.4 |
| 5 | 19.4 |
| 6 | 22.9 |
| 7 | 27.0 |
| 8 | 31.9 |
| 9 | 37.6 |
| 10 | 44.4 |
| 11 | 52.3 |
| 12 | 61.8 |
| 13 | 72.9 |
| 14 | 86.0 |
| 15 | 101.5 |
| 16 | 120.0 |
| 17 | 141.3 |
| 18 | 166.7 |
| 19 | 196.7 |
| 20 | 232.1 |
| 21 | 274.9 |
| 22 | 323.2 |
| 23 | 381.4 |
| 24 | 450.1 |
| 25 | 531.1 |

## Periscope Coordinate System

## MAXIM Periscope Requirements

**Low mass and power**
**Mounted mirror surface quality =             rms  for ******** = 1******
**Difference in entrance and exit mirror-pair spacing, ********h**
**Optical Path Difference between periscopes, OPD < ********x-ray****/10 = 1Å**
**Relative Strehl ratio > 80%**
**Position Tolerances – next slide**
**Must be able to open and close periscope aperture**
**Must be able to align images on the detector plane**
**MAXIM Mission Periscope Parameters for this study**
- Periscope spacecraft swarm diameter, D = 1 km*
- Focal length, F = 20,000 km*
- Mirror length, m = 30 cm
- Mirror width = 20 cm
- Graze angle,  = 1
- Wavelength,  = 10Å
- 		* different values used in optical analysis

## MAXIM Position Tolerances =1nm, F=20,000km, D=1km, m=30cm, =1deg, h=1m

| DOF | Mirror Equation | Periscope 
Equation | Mirror
Tolerance | Periscope
Tolerance |
| --- | --- | --- | --- | --- |
| X |  |  | ±1.7nm | ±4m |
| Y |  |  | ±0.3mm | ± 0.5mm |
| Z |  |  | ±94.7nm | ±0.32m |
| X-rot
(yaw)  |  |  | ±6.9
arcmin | ± 7.8
arcmin |
| Y-rot
(pitch) |  |  | ±2.3
marcsec | ± 10
arcsec |
| Z-rot
(roll) |  |  | ±0.13
arcsec | ±18.5
arcsec |

## h and OPD – Key Requirements

- OPD < x-ray/10

## Trade Studies

**Mirror width: 2 cm, 10 cm, 20 cm, 30 cm**
- Need to quantify the flux requirement for initial calibration
- Baseline design: 20 cm wide mirrors
- Trade mirror size versus number of spacecraft – discussed in Optical Analysis section
- Consider 20 cm versus 30 cm wide mirrors in future studies
**Mounted mirror surface quality is dependent on graze angle:**
**	****	****	****	****     ****rms  for ******** = 1******
**	****	****	****	****	**
**	****	****	****	****     ****rms  for ******** = 2******
- Chose  = 1 for this baseline design
**Internal metrology**
- Baseline design uses absolute position encoders calibrated with lasers in ground testing.

## Periscope Mass Summary

## Periscope Power Summary

- _Spacecraft Power Bus Requirement_

| End Items | Avg. Power |
| --- | --- |
| 1 Main Electronics Box |     26.6 Watts |
| Actuators @ 1 Watt each |     1 Watts |
| Drive Motors @ 1 Watt each |  1 Watt |
| Heaters |  25 Watts |
| Instrument Total:   |     53.6 Watts |

## Future Studies

**This study looked at internal periscope issues – periscope to periscope tolerancing issues still need to be addressed.**
- Look at operational control and/or mechanical options
**Mirror width**
- 2 cm width feasible?
- 30 cm width versus fewer spacecraft
- Mirror material is a factor in this trade (silicon vs. ULE)
**Further thermal and mechanical design optimization should be done.**
**See other subsystem presentations for other potential issues.**

## Up Next

**Dennis Evans will discuss the optical analysis next.**

## Backup

## OPD

**The Optical Path Difference (OPD) between any two periscopes must be within 1Å.  The OPD must be changeable with a larger (TBD) range.**
**Ways to introduce Optical Path Differences:**
- Rotate a mirror pair by 1 milliarcsecond for 1Å of OPD
- Move the entire periscope; z of 30 cm  1Å OPD (remember periscopes are tied together in each spacecraft)
- Move a mirror pair (1 and 2 or 3 and 4) in the X direction