Cruise Activity Request (CAR) Form
Observation Name: Venus 2 Airglow
Requesting Instrument: UVIS
Objective: (both measurement and scientific objectives)
Measure Venus airglow with highest spectral resolution ever achieved. Determine local time variation in Venus thermosphere composition. First spatially resolved EUV measurement of
Venus. Settle disagreement between rocket and Galileo results.
Description of Activity:
Roll s/c about z axis such that line-of-sight of UVIS (-y axis) crosses points in the plane of the trajectory about Venus ’ center.
Drift from Venus dark limb across Venus terminator to Venus bright limb. UVIS in imaging spectroscopy mode.

Activity Time Period: (window when the activity can take place)
Start ~ 20 min before closest approach
End ~ 10 min after closest approach
Activity Duration:
~30 minutes
System Requirements:
Pointing
Roll s/c about z axis such that line-of-sight of UVIS (-y axis) crosses points in the plane of the trajectory about Venus ’ center .
Power
8.3 Watts
Data volume
4.1 Mbit
Data rate
2.35 kbps
Data mode : S&ER3 or SAF_248c
Note; Data can will be buffered internally and ,r r ead out later when convenient, before UVIS shutdown, using any mode that reads UVIS science channel
Real-time commanding
No realtime commanding is required during the activity. No IEB load will be necessary. UVIS commands can be put either in the background sequence or in a mini-sequence.

Dependence on other instrument activities: (eg. support imaging required)
None
Ridealong Activities:
VIMS?
Criticality: (how important is this activity to your instrument and why)
This observation will return new and unique Venus science. It also represents an opportunity to use the instrument in a manner similar to its use for Saturn observations; thereby verifying planned Saturn configuration and operation.
Special Requirements:
Notes on Instrument Configuration:
(details about the instrument configuration that you thought about when you designed the activity and you want to document)
This observation could be implemented the same as the RPWS Venus 1: data was buffered internally in the instrument, read to the SSR, and the instrument was not powered off until the data was played back to earth.
Configuration:
HSP and HDAC are off
EUV and FUV have same configuration
Narrow slit (0.75 mrad) x 61 mrad
16 x spatial binning
1 x spectral binning
No windowing
Integration time = 32 sec
Instrument Setup

Turn off supplemental heater, turn on UVIS, load RAM from SSR, execute RAM code, set active flag, execute observation, halt observation, put UVIS in sleep mode, wait until internal buffer read by CDS (and data played back to earth), turn off UVIS, turn on supplemental heater.
( 10 commands in background sequence)
ECR or Flight Rule Reference: