Down Time, when will the solar blackout period be? |
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Down Time, when will the solar blackout period be? |
 Oct 7 2006, 03:54 PM
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Member  Group: Members Posts: 235 Joined: 2-August 05 Member No.: 451  |
Very soon, Mars will appear too close in the sky to the Sun for us to communicate very well to the MERs. Can someone say what the blackout dates will be, and especially when we start communicating again?
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| Guest_PhilCo126_* |
 Oct 7 2006, 04:38 PM
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Guests |
Wouldn't that be during the last 3 weeks of October ?
  
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Oct 7 2006, 05:06 PM
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 Senior Member Group: Members Posts: 1887 Joined: 20-November 04 From: Iowa Member No.: 110 |
Press releases from last time around may serve as an estimate.
Before: QUOTE "Based on experience with other spacecraft, we expect that when the Mars-Sun-Earth angle is 2 degrees or less, the ability to successfully communicate degrades rapidly," said JPL systems engineer Scott Doudrick, who has been organizing conjunction operations for both rovers. "To be cautious, we're allowing three days on either side of that period." AfterThe planned gap in sending daily plans runs for about 12 days beginning Sept. 8 for Spirit and Sept. 9 for Opportunity. The rovers will be instructed ahead of time to continue doing atmospheric operations and Mössbauer spectrometer readings daily during that period. No movements of the wheels or the robotic arms are in the conjunction-period plans, but the camera masts may move for making observations. The rovers also will continue communicating daily with NASA's Mars Odyssey orbiter and will also attempt to communicate directly with Earth. QUOTE Neither rover drove during a 12-day period this month, while radio transmissions were unreliable because of the Sun's position between the two planets. Daily planning and commanding of rover activities recommenced Monday for Opportunity and today for Spirit. The rovers only took images of the sky during those that period, The gap between movements was longer about 18 days.
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Oct 7 2006, 08:41 PM
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Newbie Group: Members Posts: 16 Joined: 24-January 06 Member No.: 660 |
QUOTE (alan @ Oct 7 2006, 01:06 PM)  "Based on experience with other spacecraft, we expect that when the Mars-Sun-Earth angle is 2 degrees or less, the ability to successfully communicate degrades rapidly," said JPL systems engineer Scott Doudrick, who has been organizing conjunction operations for both rovers. "To be cautious, we're allowing three days on either side of that period." Wouldn't that be the Mars-Earth-Sun angle? The Mars-Sun-Earth angle should be near 180 degrees. |
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Oct 8 2006, 01:32 AM
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#5
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Senior Member Group: Members Posts: 1636 Joined: 9-May 05 From: Lima, Peru Member No.: 385 |
For MRO with its demostration telecomunications with k-band can work up to 0.5 degree against to 2 degree for X-band.
Rodolfo |
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Oct 8 2006, 01:43 AM
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#6
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Member Group: Members Posts: 240 Joined: 18-July 06 Member No.: 981 |
QUOTE (disownedsky @ Oct 7 2006, 08:41 PM) Wouldn't that be the Mars-Earth-Sun angle? The Mars-Sun-Earth angle should be near 180 degrees. It is the angle formed by a line going from Mars to Earth to the Sun, not Mars to the Sun to Earth. Good catch. |
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Oct 8 2006, 10:02 AM
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#7
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
The Pioneer 11 Saturn encounter was just before solar conjunction, and communications degraded rapidly after about the time of closest approach to Saturn, forcing them to drop data rates progressively as they moved away from Saturn. With absolutely no onboard bulk data storage, they got what they could in realtime as the spacecraft exited the magnetosphere.
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Oct 8 2006, 02:24 PM
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#8
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Member Group: Members Posts: 235 Joined: 2-August 05 Member No.: 451 |
Thanks, so my understanding is that it will be about 18 days, starting in the next few days, and ending before the end of the month.
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Oct 8 2006, 03:15 PM
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#9
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Senior Member Group: Members Posts: 1636 Joined: 9-May 05 From: Lima, Peru Member No.: 385 |
QUOTE (antoniseb @ Oct 8 2006, 09:24 AM) Thanks, so my understanding is that it will be about 18 days, starting in the next few days, and ending before the end of the month. The 0 degree solar conjunction between Earth and Mars will be at the October 23. See at http://www.above-heavens.com The reliable X-band communications would be starting after 2 degree from the center of Sun), that is when? : Trigonometry => tang(2 degrees) =d/(150,000,000+249,200,000 km from the Sun) d = tan(2)*399 millones => 13,933,387 kilometers. Mars orbits around the Sun at the aprox speed of 86,871 km/h. Hence, the Mars' travel time from 0 to 2 degree of Sun would take = 13,933,387 km/86,871 km/h => 160.39 hours => close to 7 days. I don't know about the difference of 2 days (7 versus 9 days, it might be lead by many unprecise ciphres). Hence, October 16 (seven days before of Oct 23), the communication with Mars will start to be nill. fourteen days later, at October 31, the telecomunications with Mars will resume. Rodolfo |
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Oct 9 2006, 09:10 AM
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Junior Member Group: Members Posts: 64 Joined: 24-May 06 From: Aberdeen, Scotland Member No.: 785 |
Do you know I'm quite pleased about 18 days "downtime"
 I need that time to catch up with all the posts you guys have been making in the last 3 days while I've been away from a computer! Aberdeenastro |
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Oct 9 2006, 03:00 PM
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 Senior Member Group: Members Posts: 1281 Joined: 18-December 04 From: San Diego, CA Member No.: 124 |
QUOTE (RNeuhaus @ Oct 8 2006, 08:15 AM) The 0 degree solar conjunction between Earth and Mars will be at the October 23. What a terrible birthday present!  Well, at least this finally opened near me! I will plan on going during the opposition to hold me over. 
-------------------- Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test |
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Oct 9 2006, 09:02 PM
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#12
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Senior Member Group: Members Posts: 1636 Joined: 9-May 05 From: Lima, Peru Member No.: 385 |
QUOTE (lyford @ Oct 9 2006, 10:00 AM) What a terrible birthday present! Well, at least this finally opened near me! I will plan on going during the opposition to hold me over.  I envy you since in Lima we still has no IMAX. Good time on your birthday!. Rodolfo |
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| Guest_PhilCo126_* |
Oct 10 2006, 04:49 PM
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Guests |
Glad we have an IMAX theater in Brussels
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| Guest_Oersted_* |
Oct 10 2006, 07:53 PM
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QUOTE (PhilCo126 @ Oct 10 2006, 06:49 PM) Glad we have an IMAX theater in Brussels Huhhuhhuh, Philco, is it running in Brussels!? I'm in Brussels too! |
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Oct 10 2006, 09:03 PM
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 Member Group: Members Posts: 267 Joined: 5-February 06 Member No.: 675 |
Here's a day-by-day reckoning of the changing elongation of Mars from the Sun during the black-out period.
Steve CODE Ephemeris of Mars
Date Time (UTC) Elong ° 16 Oct 2006 00:00:00 2.4 16 Oct 2006 12:00:00 2.2 17 Oct 2006 00:00:00 2.1 17 Oct 2006 12:00:00 1.9 18 Oct 2006 00:00:00 1.7 18 Oct 2006 12:00:00 1.6 19 Oct 2006 00:00:00 1.4 19 Oct 2006 12:00:00 1.2 20 Oct 2006 00:00:00 1.1 20 Oct 2006 12:00:00 0.9 21 Oct 2006 00:00:00 0.8 21 Oct 2006 12:00:00 0.6 22 Oct 2006 00:00:00 0.4 22 Oct 2006 12:00:00 0.3 23 Oct 2006 00:00:00 0.2 23 Oct 2006 12:00:00 0.2 24 Oct 2006 00:00:00 0.3 24 Oct 2006 12:00:00 0.4 25 Oct 2006 00:00:00 0.6 25 Oct 2006 12:00:00 0.7 26 Oct 2006 00:00:00 0.9 26 Oct 2006 12:00:00 1.1 27 Oct 2006 00:00:00 1.2 27 Oct 2006 12:00:00 1.4 28 Oct 2006 00:00:00 1.5 28 Oct 2006 12:00:00 1.7 29 Oct 2006 00:00:00 1.9 29 Oct 2006 12:00:00 2.0 30 Oct 2006 00:00:00 2.2 30 Oct 2006 12:00:00 2.3 |
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