1. GrAnd Unification and Gravity Explorer
GAUGE
GrAnd Unification and Gravity Explorer

2. Consortium
K. Aplin1, R.J. Bingham1, M. Caldwell1, A.M. Cruise2, P. D’Arrigo3, H. Dittus4, J. Hough5, P. Jetzer6, N. Lockerbie7, F. Loeffler8, J. Mester9, C. Pegrum7, D. Shaul10, T. J. Sumner10, S. Theil4, C. Torrie5, P. Touboul11, C. Trenkel10, S. Vitale12, W. Vodel13, C. Wang14, H. Ward5
1RAL, UK
2University of Birmingham, UK
3EADS Astrium, Stevenage, UK
4ZARM, University of Bremen, DE
5University of Glasgow, UK
6ITP, University of Zurich, CH
7University of Strathclyde, UK
8PTB, Braunschweig, DE
9University of Stanford, US
10Imperial College London, UK
11ONERA, Paris, FR
12University of Trento, IT
13University of Jena, UK
14University of Aberdeen, UK

3. Background
ESA Cosmic Vision call for ideas (2004): approx. 50 ideas submitted, separately, in the area of “Fundamental Physics”
Informal feedback: in some cases significant overlap between proposed ideas → community should unite behind a few, strong proposals
Now: call for Cosmic Vision Mission Proposals in the near future…

4. Scientific Motivation
GAUGE: Combine experiments that address key issues at the interface between gravity and quantum interactions
Currently considered (NOT EXHAUSTIVE OR EXCLUSIVE):
Equivalence Principle tests
G/ISL measurements
Search for spin-dependent effects
Decoherence in Atom Interferometers …?

5. Experiment concepts (to be selected from …)
EP measurement – Microscope, STEP – studied extensively within ESA/NASA
Microscope 1 part in 1015
STEP 1 part in 1018

6. Experiment concepts - II
G and 1/r2 – STEP, ISLAND – better than 1 part in 105
(Possibility of LISAPF G measurement – 1 part in 104)
(Quinn et al. 2001)
Disagreement 2x10-4

7. Experiment concepts - III
Spin-dependent effects – STEP, SSPIN

8. Experiment concepts - IV
Quantum decoherence - HYPER
laser beam
atom beam
detector
spacetime fluctuations
fringe analyzer

9. Common technologies All potential experiments require
Drag-free environment
Precision displacement sensing of “proof-masses”
Magnetic (SQUIDS)
Electrostatic (Capacitive sensing)
Optical (Interferometry)
Cold atoms (Interferometry)

10. Heritage Readout Magnetic GP-B, STEP
Optical / Capacitive LISAPF, Microscope
Cold Atom HYPER + ground
Spacecraft
Bus – LISAPF
Drag-free – LISAPF + LTP
Space Experience within team
Astrium / Birmingham / Imperial / Onera / RAL / Stanford / Trento / ZARM

11. Mission Concept
Provide drag-free environment using LISAPF bus with LTP inertial sensor
Modular experiment bays – different environments possible
Launch into LEO sun-synchronous orbit with VEGA
Thermal Stability
Earth as Source

12. Some key dates VEGA maiden flight: end 2007
LISA PF success demonstrated: end 2010
… even allowing for delays, this should happen in time for mission in

13. “Recipe” for success
Launcher, Spacecraft Bus and Drag-free Platform: existing technology 
Payload: choose according to
Scientific Merit
Feasibility
Affordability
Inevitable Compromise

14. Plans
Submit Cosmic Vision Mission Proposal to ESA (deadline Summer 2007)
So far at UK level: well-received presentation to national Research Council (PPARC)
Several meetings planned in the near future:
Experimental concepts input and definition of Science Team
Experimental layout definition
Initiate industry-led accommodation study

15. Summary
GAUGE is a mission at the interface of gravity and its unification with other interactions
Mature technology
Experienced team
Fits into medium mission cost envelope
→ open invitation to collaborators!

16. … if interested please contact