# Presentation: 821842

## GLAST 

**Mission Formulation**
**Jonathan Ormes**
**Project Scientist**
***Jonathan.F.Ormes@nasa.gov***

**GLAST Users Group**
**GSFC, October 22, 2003**

## Mission Objectives

**Mission Objectives**

**Understand the mechanisms of particle acceleration in astrophysical environments such as active galactic nuclei, pulsars and supernova remnants**
**Determine the high energy behavior of gamma-ray bursts and other transients**
**Resolve and identify point sources with known objects**
**Probe dark matter and the extra-galactic background light in the early universe**

## GLAST: DOE and NASA Partnership

**Gamma ray Large Area Space Telescope (GLAST)**
***An astro-particle physics partnership to explore the high-energy universe***

**Department of Energy Office of Science**

**NASA - Office of Space Science**

***Chart the evolution of the universe, from origins to destiny***
***1. Understand the structure of the universe***
***2. Explore the ultimate limits of gravity and and energy in the universe***
***3. Learn how galaxies, stars and planets form, interact and evolve***

**Particle physics**

**Astronomy/astrophysics**

## GLAST is an International Mission

**NASA - DoE Partnership on LAT**
**LAT is being built by an international team**
**	****	****Si Tracker:**** ****Stanford, UCSC, Japan, Italy**
**	****	****CsI Calorimeter:**** ****NRL, France, Sweden**
**	****	****Anticoincidence:**** ****GSFC**
**	****	****Data Acquisition System:**** ****Stanford, NRL**
**GBM is being built by US and Germany**
**	****	****Detectors:**** ****MPE**

## GLAST Project Organization

- Kevin Grady**GLAST Project Manager**
- September 9, 2003

**Project Manager****K. Grady**
**Deputy Project Manager****A.Vernacchio**
**DPM/R****M. Seidleck**
**Secretary****L. Barbour**

**Project Scientist****J. Ormes**
**Deputy Project Scientists Steve Ritz/Neil Gehrels**

**Science Working     Group**

**Flt Software ****E. Andrews**

**Financial Mgr.****L. Tall**

**PSM****W. Hensley**

**Contract Officer****J. Edmond**

**Systems Manager****J. Leibee**

**Safety Mgr. D. Bogart**

**Sys Assurance Mgr.****R. Kolecki**

**Power – E. Gaddy****	****	****CDH – J. Sonsino**
**ACS – E. Stoneking****	****Comm – P. Acosta, G. Humphrey**
**Propulsion – M. Underdown****	****Thermal – T. McCarthy, L. Fantano**
**Electrical – F. Blanchette****	****Contamination – C. Lorentsen**
**Structures/Mechanism – S.Seipel  ****	****I&T – E. Shippey                                       ****	****F. Tahmasebi ****	****	****	****           ****	****C. Fransen**

**Instrument Sys Mgr.****T. Venator**

**Observatory Mgr.****J. Bretthauer**

**GBM Instr Mgr****B. Browne**

**Launch Services Mgr.****M. Goeser**

**MOGS Mgr.****M. Rackley**

**MOC Mgr.****D. Small**

**CM J. Chipouras**
**Schedules     M. Walsh**
**Library           M. Rich**
**Data Mgmt/PS B. Townsend**

**Res Analyst****vacant**

**Mission Systems****N. Rioux**
**Systems:            ****M. Melton                               T. Ford                C. Connor           B. Garnett**

**QE****T. Alvarez**
**Parts****T. Perry **
**S/W QE****D. Harmon**
**Reliability****T. Di Venti**
**LAT On-site****T. Shepherd**
**S/C On-site****M. Kunda**

**Systems ****A. Whipple**

**Systems:**
**R. Cox           E. Canevari B. Wagner**

**Science Lead****D. Band**

**C. Mako (KSC)**

**SSC Mgr.****J. Norris**

**P. Versteegen**

**Systems        A. Guha**

**Original signed**

**J. Anderson**

**EPO Manager**
**L. Cominsky**

**LAT Instr Mgr****B. Graf**

**On-site Sys – J. Ku**
**ACD I/F – S. Mengers**

## Science Requirements

**High Energy Gamma Rays: 20 MeV - > 300 GeV**
**Source location <0.5 arcmin**
**High latitude source of 10****-7**** cm****-2**** s****-1**** flux, E****-2**** spectrum,**
**1 ******** radius, after 1 yr survey**
**Point source sensitivity < 6 x 10****-9**** cm****-2**** s****-1****  **
**High latitude source after 1 yr survey, 5 ******** detection**
**Background to be < 10% of extragalactic high latitude diffuse emission**
**Conduct broad band study of gamma ray bursts**
**Determine burst spectra from <10 keV to ~30 GeV**
**Determine burst locations <15 degrees and send to the GRB notification network (GCN) within 7 seconds**

## Mission Requirements and Observing Plan

**Spacecraft **
**Pointing knowledge < 10 arcseconds (1********)**
**Observatory is designed to “point anywhere, anytime”**
**Operate without pointing at the Earth**
**Reorient quickly and autonomously to follow a transient or respond to a target of opportunity**
**Slew 75 degrees in 10 minutes**
**3 normal operational modes**
**Scan (baseline)**
**Inertial pointing**
**Scan pointing - takes advantage of the wide field of view to optimize time on sky**
**Mission Lifetime 5 years, Goal 10 years ****(subject to Senior Review)**
**Observatory checkout 30-60 days**
**First year is scanning to make all sky survey**
**Planned observations subject to interruption for extraordinary transients **
**Second year and beyond - operational mode driven by competitive proposals**

## Guest Investigator Program

**GI program starts during the survey **
**10-15 GIs**
**Will grow to ~100 Guest Investigations funded by NASA each year.**
**GLAST Fellows program**
**Continue Interdisciplinary Scientist (IDS) Program**
**	****C. Dermer (NRL)**** - non-thermal universe**
**	****B. Dingus (Los Alamos)**** - transients**
**	****M. Pohl (Iowa State U.)**** - diffuse galactic**
**	****S. Thorsett (UCSC)**** - pulsars**
**Program of Education and Public Outreach continues throughout the mission**

## Science Review History Highlights

** ****Selected as mission concept study, 1994 (PI: Michelson, Stanford)**
** ****Endorsed by Gamma-Ray Astronomy Program Working Group as highest priority in gamma-ray astronomy, 1996**
** ****Chosen as top priority (with Constellation-X) by Structure and Evolution of the Universe Subcommittee, 1997**
** ****Reviewed by SAGENAP, presented to HEPAP, and approved by DoE, 1998**
**Science Requirements Document****, drafted by Facility Science Team, signed in July 1999. **
** ****NASA AO: August 1999.  **_**Selections**_**: February-March 2000.**
** ****GLAST is the highest-ranked Moderate Size space-based initiative in the National Academy of Sciences 2000 Decadal Survey Report.**

## GLAST Instruments

**GLAST Instruments**

**Large Area Telescope (LAT)**
**PI: Peter Michelson **
**Stanford University**

**GLAST Burst Monitor (GBM)**
**PI: Charles Meegan**
**Marshall Space Flight Center**

## Large Area Telescope Parameters

**Energy Range**
**Energy Resolution (********E/E)**
**Effective Area (1GeV)**
**Field of View**
**Angular Resolution**
**Sensitivity (> 100 MeV)*******
**Deadtime**
**Mass**
**Lifetime**
*** ****1 year survey at high latitudes**

**CGRO/EGRET**
**20 MeV - 30 GeV**
**0.1**
**1500 cm****2**
**0.5 sr**
**5.8° @ 100 MeV**
**0.5° @ 10 GeV**
**~ 10****-7**** cm****-2**** s****-1**
**100 ms**
**1810 kg**
**1991 - 1997**

**GLAST/LAT**
**20 MeV - > 300 GeV**
**0.1**
**10,000 cm****2**
**2.4 sr**
**~ 3.5° @ 100 MeV**
**~ 0.1° @ 10 GeV**
**~ 3 ******** 10****-9**** cm****-2**** s****-1**
**<10 ********s**
**3000 kg**
**2006 - 2016**

**Increased area, field of view, angular resolution, extended energy range and operational efficiency provide a powerful combination!**

**Change**
**10 to 300 GeV**
** **
**6.6**
**4.8**
**Area = 1/2.7**
**Area = 1/25**
**1/30**
**> 5**

## GLAST Burst Monitoring

**GBM provides low-energy context measurements with high time resolution**
**Broad-band spectral sensitivity**
**Contemporaneous low-energy & high-energy measurements**
**Continuity with current GRB knowledge-base (GRO-BATSE)**

**LAT and GBM work synergistically to make new GRB observations**

**Provides rapid GRB timing & location triggers w/FoV > LAT FoV**
**Improved sensitivity and response time for weak bursts**
**Follow particularly interesting bursts for afterglow observations**
**Provide rapid locations for ground/space follow-up**

## Science Topics

**Active Galactic Nuclei**
**Isotropic Diffuse Background Radiation**
**Cosmic Ray Production:**
**Molecular Clouds**
**Supernova Remnants**
**Normal Galaxies**
**Endpoints of Stellar Evolution**
**Neutron Stars/Pulsars**
**Black Holes**
**Unidentified Gamma-ray Sources**
**Dark Matter**
**Solar Physics**
**Gamma-Ray Bursts**

## From EGRET to GLAST (>100 MeV)

**Map the gamma-ray sky with sensitivity     > 30 times that of EGRET without becoming source confusion limited.**

## GLAST Project Master Schedule

**Instrument preliminary Design Reviews completed**
**Spacecraft contractor selected: Spectrum-Astro**
**S/C PDR May 2003**
**Critical Design Reviews for instruments **
**Held LAT May 2003**
**GBM June 2004**
**CDR for Spacecraft scheduled for spring 2004**
**Instrument deliveries in 2005**
**GBM fall**
**LAT December **
**Launch in Feb 2007**

## GLAST Ground System

**User**** community**

## Earth Avoidance for Pointed Observations

- Orbit Plane

- Rotation of Earth’s Disk

- Rotation of Earth’s Disk

- 134o dia Earth Disk

_**Before Occultation**_

_**After Occultation**_

**Earth Avoidance for Pointed Observations**

**Earth’s disk is receding to the right**
**FOV is picking up inertial target**

- Spacecraft Centered Celestial Sphere

**Earth’s disk is approaching from the left**
**FOV is losing inertial target**

## Scan-pointing

## GLAST Mission Overview

## Huge FOV (20% of sky) allows primarily scanning operations
Opens unexplored region > 10 GeV
Unprecedented PSF for gamma rays (factor 5 better than EGRET at 10 GeV)
Expect to find new classes of gamma-ray sources with the improved sensitivity
No expendables  potential for long mission without degradation
Large sensitive area (> 6 EGRET) for transients
Quick reaction to gamma-ray bursts and other transients

**Opens unexplored region > 10 GeV**
**Unprecedented PSF for gamma rays (factor 5 better than EGRET at 10 GeV)**
**Expect to find new classes of gamma-ray sources with the improved sensitivity**
**No expendables ******** potential for long mission without degradation**
**Large sensitive area (> 6******** EGRET) for transients**
**Quick reaction to gamma-ray bursts and other transients**

**Summary of Capabilities**

## GBM Capabilities

|  | BATSE | GBM - Requirement | GBM - Current Design |
| --- | --- | --- | --- |
| Energy Range | 25 keV – 10 MeV | <10 keV – >25 MeV | 6 keV - 30 MeV |
| Field of View | All sky not occulted by Earth | >8 sr | 8.7 sr |
| Energy Resolution | <10% | <10% (0.1-1.0 MeV, 1 on-axis) | 7% (100 keV)
5% (1 MeV) |
| Deadtime |  | < 10 s/event | 2.5 s/event |
| Burst Sensitivity - Ground (5, 50-300 keV) | 0.2 cm-2 s-1 | <0.5 cm-2 s-1 | 0.45 cm-2 s-1 |
| Burst Sensitivity - On-board (5, 50-300 keV, 50% efficiency) |  | <1.0 cm-2 s-1 | 0.78 cm-2 s-1 |
| GRB Alert Location | ~25 | - | <15 |
| GRB Final Location | 1.7 | - | <1.5 |
| GRB Notification Time to Spacecraft |  | <2s | 2s (arbitrarily selectable, trade-off between speed & accuracy) |

**GBM Capabilities**

## LAT Capabilities

|  | EGRET | LAT - Requirement | LAT - Current Design |
| --- | --- | --- | --- |
| Energy Range | 20 MeV – 30 GeV | 20 MeV – 300 GeV | 20 MeV - 300 GeV |
| Energy Resolution | 10 % | <10%, 0.1–100 GeV (1, on-axis) | ~9%, 0.1–100 GeV |
| Effective Area | 1500 cm2 | >8000 cm2 (maximum value, 1-10GeV) | 10,000 cm2 at 10 GeV |
| Point Source Sensitivity
(5, >100 MeV) | ~1  10-7 cm-2 s-s | <6  10-9 cm-2 s-2  (at high gal. latitude for 1-year sky survy, for photon index of -2) | 3  10-9 cm-2 s-2  |
| Angular Resolution | 5.8 (100 MeV) | <3.5 (100 MeV)
<0.15 (>10 GeV) | 3.4 (100 MeV)
0.086 (>10 GeV) |
| Source Location Determination | 15 arcmin | <0.5 arcmin (1 radius, flux 10-7 cm-2 s-1 at 100 MeV, high gal latitude) | 0.4 arcmin |
| Field-of-view | 0.5 sr | >2 sr | 2.4 sr |
| Timing Accuracy | 100 s | <10 s | TBD |
| Deadtime | 100 ms/event | <100 s/event | TBD |
| GRB Location Accuracy On-Board |  | <10 arcmin | 5 arcmin |
| GRB Notification Time to Spacecraft |  | <5 s | TBD |

**LAT Capabilities**