SREM onboard STRV1-c

1. Description of activity

The next two microsatellites in the Space Technology and Research Vehicle (STRV) programme of the UK Defense Evaluation and Research Agency (DERA), STRV1-c and STRV1-d, will be launched into geostationary transfer orbit in 1999. One of the two satellites, the STRV1-c, will be carrying ESA's Standard Radiation Environment Monitor (SREM) unit to measure energetic electrons, protons, and heavy ions, as well as the total accumulated dose, encountered during the mission. This information will be made available in real time to the other experimenters onboard the satellite and, in due course, implemented as a part of the overall SREM measurement data base at the Paul Scherrer Institute (PSI), Switzerland, together with data from other SREM units in other missions.

In many ways, the SREM/STRV1-c mission can be seen as a follow-on activity to the successful REM flights onboard STRV1-b and the Russian space station MIR. Valuable new results concerning e.g. flux anisotropy, electron belt dynamism, and seasonal changes have been obtained, and it is anticipated that such discoveries will be continued to be made by the SREM during the STRV1-c mission.

2. Team responsible

The operator and owner of the STRV1-c&d spacecraft is DERA, while the SREM data will be handled by PSI. The mission requirements of the SREM have been defined by ESTEC (TEC-EES). The contact persons are :

A. Mohammadzadeh, ESTEC (TEC-QCA), SREM project manager for STRV-1c
E. Daly, ESTEC (TEC-EES), co-investigator, mission definition
P. Nieminen, ESTEC (TEC-EES), co-investigator, mission definition
Pierrik Vuilleumier, ESTEC (TEC-SP), SREM engineering designer
Roberto Aceti, ESTEC (IMT-TTD), SREM sponsor
Paul Buehler, PSI, SREM principal investigator
Alex Zehnder, PSI, co-investigator
Wojtek Hajdas, PSI, co-investigator, simulations
Angela Cant, DERA, STRV1-c spacecraft manager

3. Meetings

1st STRV1-c&d Quarterly Progress Meeting, Farnborough, 4 June 1997
STRV1-c&d Radiation Experiments Group meeting, Farnborough, 4 June 1997
2nd STRV1-c&d Quarterly Progress Meeting, Farnborough, 9 September 1997
STRV1-c&d Radiation Experiments Group meeting, Farnborough, 10 September 1997
3rd STRV1-c&d Quarterly Progress Meeting, Farnborough, 9 December 1997
4rd STRV1-c&d Quarterly Progress Meeting, Farnborough, 2 April 1998
5th STRV1-c&d Quarterly Progress Meeting, Farnborough, 30 June 1998
6th STRV1-c&d Quarterly Progress Meeting, Portsdown, 9 September 1998
STRV1-c&d Radiation Experiments Group video conference, Farnborough, 7 December 1998
7th STRV1-c&d Quarterly Progress Meeting, Farnborough, 8 December 1998

The minutes of the meetings are maintained by DERA in their ftp site. If these, or some of the other documentation is required, please contact P. Nieminen at ESTEC (TEC-EES).

4. Energy binning

The table below summarises the envisaged proton and electron energy binning of SREM onboard STRV1-c. There is room for adjustments in the discriminator levels, such that other binning schemes, more suitable to other types of radiation environments than the GTO, can also be implemented. For more information on the technical details of the SREM, please contact H.J. Schneider at the SREM manufacturer Oerlikon-Contraves.

	Logic	dE discr. level [MeV]	Particle	E min [MeV]	E max [MeV]
1.	D1	0.085	Proton Electron	20 1.0	Inf.
2.	D1	0.25	Proton	20	550
3.	D1	0.6	Proton	20	120
4.	D1	2.0	Proton	20	27
5.	D1	3.0	Proton	20	34
6.	D2	0.085	Proton	39	Inf.
7.	D2	9.0	Ions	Dep. on Z	Dep. on Z
8.	D1*D2	0.6, 2.0	Proton coincidence	40	50
9.	D1*D2	0.6, 1.1-2.0	Proton coincidence	50	70
10.	D1*D2	0.6, 0.6-1.1	Proton coincidence	70	120
11.	D1*D2	0.085-0.6, 0.085-0.6	Proton coincidence	130	Inf.
12.	D3	0.085	Electron Proton	0.5 10	Inf.
13.	D3	0.25	Electron	0.55	2.3
14.	D3	0.75	Proton	11	90
15.	D3	2.0	Proton	11	30