# Presentation: 825361

## SuperNova/Acceleration Probe

**SuperNova/Acceleration Probe**
**SNAP Study**

**Dave Peters**
**George Roach**
**June 28, 2001**

- ...a man who's willing to make a decision in the first place can always make another one to correct any mistake he's made. _Harry S. Truman_

## Launch Vehicle Volume Comparisons 
Configurations
Launch
Deployed
Bus layout
Mechanical Mass, Cost, & TRL
Mass Properties
Issues and Concerns
Back-ups
Launch vehicle lift capacity comparisons

**Configurations**
**Launch**
**Deployed**
**Bus layout**
**Mechanical Mass, Cost, & TRL**
**Mass Properties**
**Issues and Concerns**
**Back-ups**
- Launch vehicle lift capacity comparisons

**Topics**

## Launch Vehicle Volume Comparisons

- Delta II

- Atlas EPF

- Delta III

_**SeaLaunch**_

- 6.57 M

## Deployed Configuration

**Deployed Configuration**

- Propulsion Tanks

- Sub-system
- electronics

- Secondary Mirror
- and
- Mount

- Optical Bench

- Primary Mirror

- Thermal
- Radiator

- Solar Array
- Wrap around, body mounted
- 50% OSR & 50% Cells

- Detector/Camera
- Assembly

## Bus Layout

- Propulsion Tanks

- 5# thrusters
- (4 sets of 2)

- Sub-system electronics

- Sub-system electronics

- Sub-system electronics

- FIDO electronics

- Momentum Wheels
- (4 Ithaco “B”)

**Points to consider**
-  Mass balance
-  Thermal
-  Access for servicing propulsion tanks
-  Integration and  test access

## Mechanical Mass, Cost, & TRL(composite structure assumed)	

**Mass (kg)**
- Bus Structure
- Thrust tube	 33 (can be lower - not structural)
- Plates	 31
- Misc. brackets, clips, etc._	__ 79_
- 		143 total
**TRL #6 ****: System/subsystem model or prototype demonstration in a relevant environment (ground or space)**
- Subsystem prototypes or models of the proposed bus have been successfully tested under space conditions in orbital flight, but _in a bus configuration different than the proposed bus_.
- Bus prototypes or models will require _major modifications_ for proposed mission.  This will require flight requalification.
- Proven launch vehicle to be used.

## Mass Properties

**Mass Properties**

**Spacecraft**
- Lift-off
- C.G.....................  23.4, -126.3, 1186.0 (mm)
- Inertia’s wrt C.G.
- Ixx .................. 3.6e9
- Iyy .................. 3.3e9
- Izz ..................  2.1e9

- X

- Y

- Z

## Mechanical Issues and Concerns

**Mechanical ****Issues and Concerns**

**RSDO Spacecraft Bus**
- There are several “RSDO” buses that could accommodate this mission.  However, due to the unique payload instrument interface, extensive re-design of the mechanical structure is necessary. A mission unique structure will be mandatory. At this time we feel that there will be sufficient volume to accommodate the sub-system components. The main concern being the reaction wheels and their relationship to the C.G.
**Mass and Volume**
- No mass problem
- Volume is close on the Delta III and Atlas EPF.
- This volume conflict is very slight and could be resolved by a slight reduction of the MLI Shroud Assembly
**Mechanical interfaces**
- Mission axial C.G. height within limits for launch vehicle PAF.
- Mission lateral C.G. are within limits for launch vehicle PAF.
- Mission stiffness for launch vehicle is TBD at this phase of the study.

## BACK-UP
Slides

**Slides**

## Launch Vehicle Performance(Delta III)

- -2

- 2700

## Launch Vehicle Performance(Atlas III)

**Launch Vehicle Performance****(Atlas III)**

- -2

- 3100

## Launch Vehicle Performance(Sea Launch)

**Launch Vehicle Performance****(Sea Launch)**

- -2

- 3300