Live from the Hubble Space Telescope

UPDATE # 12A (Special edition on the upcoming television program)

PART 1: Watching the program

PART 2: Asking questions during the program

PART 3: Tracking the location of the HST during the program

PART 4: What the HST is doing during the show

Watching The Program

It is hard to believe that the time has finally come for the first live television program . The program "Making YOUR Observations" will air on Thursday, March 14 from 1-2:00pm Eastern. We hope you'll be able to join us as we take the first look together at our original Hubble data. Our fingers are crossed that the data will be good; of course, since this is real science, there is a risk that the observations will not work. We'll know tomorrow.

The best best for viewing the program is your local PBS station. Many stations are carrying the program live. For a national listing of PBS stations and their LHST plans, consult this page.

The program will also be available on two separate satellites. PBS will broadcast on the Ku-band via Telstar 401 (97 degrees West, transponder 8, horizontal, 11915 Mhz, audio on 6.2 and 6.8) NASA TV will broadcast on the C-band via Spacent 2 (69 degrees West, transponder 5, channel 9, horizontal, 3880 Mhz, audio on 6.8)

Also, the program will be sent via digitized video over the Internet. This option preserves the live aspect of the programming, but the result will suffer from reduced video and audio quality. Various technologies will be employed.

The program will be piped into the MBONE from NASA Ames; check your MBONE scheduling tools for details.

Carolyn Sumners of the Houston Museum of Natural Science is supporting the broadcasts for both CU-SeeMe and Apple Teleconferencing (broadcast mode) at the following addresses: CU-SeeMe: and Apple Teleconferencing - Broadcast mode:

CU-SeeMe will also have the talk window for transcription of the audio (for slow users) and for asking questions. Whenever the audio calls for questions, the CU-SeeMe crowd can ask as well. Carolyn will make files from the talk windows and email them to you.

For testing purposes, use the reflector.

Asking Questions During the Program

During the live television program, we will be accepting questions from you; some of these questions will be read on-air and answered on the spot.

Since time is very limited during the television program, only a small number of questions will actually be able to be read on-air. So we hope you will not be too disappointed if your question is not chosen. 

We will also accept questions via FAX; the number to use for this is 410-338-5075

Please do not send email or FAXs before the start of the program. Your question has the best chance of being used if it directly relates to the topics being covered in the program.

Tracking the Location Of the HST During the Program

Here is a potential student activity.

Plot the ground track position of the HST during the show.

The following table has the time, latitude, and longitute. Find a world map and plot each point.

                                Height  North    West      Satellite
 DOW   MM/DD/YY   HH            km      Lat      Long      Visibility

 Thu   03/14/96  1:00:00 PM     593.2   24.21    -79.12    In Darkness
 Thu   03/14/96  1:05:00 PM     593.0   27.79    -98.26    In Darkness
 Thu   03/14/96  1:10:00 PM     592.8   28.24    -118.15   In Darkness
 Thu   03/14/96  1:15:00 PM     592.7   25.49    -137.61   In Darkness
 Thu   03/14/96  1:20:00 PM     592.7   20.01    -155.71   In Sunlight
 Thu   03/14/96  1:25:00 PM     592.7   12.59    -172.32   In Sunlight
 Thu   03/14/96  1:30:00 PM     592.6   4.06     172.15    In Sunlight
 Thu   03/14/96  1:35:00 PM     592.4   -4.81    156.97    In Sunlight
 Thu   03/14/96  1:40:00 PM     592.2   -13.27   141.37    In Sunlight
 Thu   03/14/96  1:45:00 PM     591.9   -20.56   124.65    In Sunlight
 Thu   03/14/96  1:50:00 PM     591.7   -25.84   106.41    In Sunlight
 Thu   03/14/96  1:55:00 PM     591.7   -28.33   86.87     In Sunlight

All time are Eastern Standard Time

What the HST will be Doing during the Show

It's day 74 of 1996 at 1800 hours Greenwich Mean Time (GMT). [Note: 1800 GMT = 1:00PM Eastern] The Hubble Space Telescope (HST) is passing over central India headed northeast at an altitude of 320 nautical miles. The HST has already completed 12 of the 15 orbits it makes each day. The satellite is in orbit night. It is drawing power stored in its six batteries. The telescope's current target is occulted by the earth. The Faint Object Spectrograph (FOS) instrument is activated waiting to resume its work once the target is back in view. The other instruments (Faint Object Camera, Goddard High Rate Spectrograph, and the Wide Field Planetary Camera II ) are not active. The FOC and GHRS are in HOLD. The WFPC-II is in standby mode. The satellite is not in radio contact with the ground. There is a small part of HSTs orbit where it is not in view of the Tracking and Data Relay Satellite (TDRS) it uses. This area is called the Zone of Exclusion (ZOE).

18:04:24 The satellite is now over southern China headed northeast. It points its high gain antenna (HGA) (number 2) to the TDRS-WEST satellite and turns on is transmitter. The signal travels up to the TDRS and is received and retransmitted to the TDRS Ground Terminal located in White Sands, New Mexico. From there the signal is relayed to the Space Telescope Operations Control Center (STOCC) at the Goddard Space Flight Center (GSFC) located in Greenbelt, Maryland.

The satellite sends back measurements from all of its subsystems. The computers onboard take measurements of voltage, current, temperature, and position using sensors located throughout the satellite. The computer packs the measurements together and transmits them. The control center unpacks the measurements and checks each one for abnormal behavior.

18:09:23 The STOCC establishes forward link communication with the satellite via the TDRS. The forward link allows the STOCC to uplink real-time or stored commands and new flight software.

18:09:25 The HST has been tracking a target (stars that the rings of Uranus will occult). The Pointing Control Subsystem performs a small attitude adjustment to align the target with the FOS aperture. It uses its reaction wheel assembly (RWA) and gyros.

18:09:53 The satellite has now moved further in its orbit. Its now over southeast China, headed southeast over the Philippine Sea. The Pointing Control System (PCS) begins to prepare its Fine Guidance Sensors (FGS) to find the guide stars near its target.

18:10:50 The earth no longer blocks the target. The occultation is complete. During the next few minutes the FGS slowly moves around to find its guide star.

18:16:16 The satellite begins tracking the FOS target. This is called a type 3 slew.

18:17:01 The FOS begins to take measurements of its target. The data from the instruments is recorder by a tape recorder onboard.

18:19:11 The satellite passes from orbit night into orbit day. The solar arrays begin to generate electricity. The Electrical Power Subsystem uses this power to recharge the batteries and run the spacecraft.

18:22:53 The Fixed Head Star Tracker #3 view is blocked (occulted) by the earth. It is not needed at this part of the schedule. As the satellite continues in its orbit, the other 2 FHST views will be blocked as well.

18:25 HST is heading southeast over the Pacific near the Marshall Islands.

18:24:32 The FOS begins to take its second measurements of its target. The data from the instruments is recorded by a tape recorder onboard.

18:28:27 The Fixed Head Star Tracker #2 view is blocked (occulted) by the earth.

18:30:00 HST is heading southeast, southwest of the Hawaiian Islands.

NOTE: (The timeline depicts a Corrective Optics Space Telescope Axial Replacement (COSTAR) Deployable Optical Bench (DOB) movement. This activity has been replaced by a movement of the Secondary Mirror.)

18:31 During the next 22 minutes the HST Secondary Mirror will be re-adjusted by sending real-time commands to its actuators. There are 6 actuators on the back of the secondary mirror, and each are moved one at a time the same amount. Once all actuators are commanded, the mirror would have been moved by only 6 micro-meters further apart from the primary mirror. This is needed to correct for continuous but slow shrinkage of the structure on which the mirrors are mounted, due to water loss (on Earth, components absorb a certain amount of water, which then escapes to the vacuum of space once in orbit).

18:34:48 The Fixed Head Star Tracker #1 view is blocked (occulted) by the earth.

18:40 HST is heading southeast over the south Pacific, east of French Polynesia.

18:50 HST is heading southeast over South Pacific approaching coast of South America/Chile.

18:51:53 The satellite loses forward link communications. No commanding from the STOCC is possible.

18:53:22 The satellite loses return link communications with TDRS (WEST). The STOCC cannot monitor the engineering telemetry data until communications is re- established.

18:53:53 The satellite establishes forward and return link communications. Commanding from the STOCC is possible.

18:54:22 One of the onboard tape recorders (number 1) is filled with science data. The data is played back and transmitted via TDRS to the ground and back to GSFC. It is processed by the Packet Processor II (Pacor II) Data Capture Facility, transferred to the Data Distribution Facility (DDF) , then transferred to the Space Telescope Science Institute in Baltimore, Maryland.

18:55:18 The satellite enters the South Atlantic Anomaly (SAA). This will last for the next 19 minutes.

18:59 The satellite's view is occulted for the next 15 minutes.

18:59:20 Using the PCS, the satellite begins to slew to a new target.

19:00 The satellite is now passing over South America/Chile. In 22 minutes the HST will begin its 32,118 orbit of earth.