** The Official Space Flight Thread - The Space Station and Beyond **

SkScotchegg

SkScotchegg

SkScotchegg

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Hi there, I was wondering if someone could please answer this questions as I'm interested in space/science too.

I was wondering how long it took for data to be transmitted from mars rovers to earth, I came across this article:

http://marsrover.nasa.gov/mission/comm_data.html

Which shows this:
Communications With Earth

How Fast and How Much Data the Rovers Can Send Back

The data rate direct-to-Earth varies from about 12,000 bits per second to 3,500 bits per second (roughly a third as fast as a standard home modem). The data rate to the orbiters is a constant 128,000 bits per second (4 times faster than a home modem). An orbiter passes over the rover and is in the vicinity of the sky to communicate with the rovers for about eight minutes at a time, per sol. In that time, about 60 megabits of data (about 1/100 of a CD) can be transmitted to an orbiter. That same 60 megabits would take between 1.5 and 5 hours to transmit direct to Earth. The rovers can only transmit direct-to-Earth for at most three hours a day due to power and thermal limitations, even though Earth may be in view much longer.

Mars is rotating on its own axis so Mars often "turns its back" to Earth, taking the rover with it. The rover is turned out of the field of view of Earth and goes "dark", just like nighttime on Earth, when the sun goes out of the field of view of Earth at a certain location when the Earth turns its "back" to the sun. The orbiters can see Earth for about 2/3 of each orbit, or about 16 hours a day. They can send much more data direct-to-Earth than the rovers, not only because they can see Earth longer, but because they can operate their radio for much longer since their solar panels get light most of the time, and they have bigger antennas than the rovers.
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Which answered my question, but then gave me a 2nd question which is why does the time data takes to transmit to earth fluctuate between 1.5 to 5 hours, I was wondering if radiation in space effects this or some other type of unknown forces? Solar system weather or mars weather etc?

EDIT: or in fact, after re-reading that passage I copied/pasted, have I miss read it, and it doesnt say how long it takes to get to earth at all? It it just saying if the mars rover were to send the data direct to earth it would be 1.5 to 5 hours...but it doesn't, it actually sends it direct to the orbiters which is "128,000 bits per second"? And therefore doesn't answer my original question of how long does it actually take to get to earth? In which case maybe the question should be how long does the orbiter take to send the data to earth? I'm confused lol...can someone please explain this to me lol :rolleyes:

Thanks in advance.
 
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Glaucus

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Its saying 60mbs of data would take 1.5-5hrs due to the low speed.

Physical time is about 6minutes, depending on distance between earth and mars due to different orbits and speed, its just distance / speed of light.

List of some distances.
•Dec. 24, 2007 – 88.2 million km (54.8 million miles)
•Jan. 29, 2010 – 99.3 million km (61.7 million miles)
•Mar. 03, 2012 – 100.7 million km (62.6 million miles)
•Apr. 08, 2014 – 92.4 million km (57.4 million miles)
•May. 22, 2016 – 75.3 million km (46.8 million miles)
•Jul. 27. 2018 – 57.6 million km (35.8 million miles)
•Oct. 13, 2020 – 62.1 million km (38.6 million miles)


Read more: http://www.universetoday.com/14824/distance-from-earth-to-mars/#ixzz2pq1iQQzZ
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Speed of light is 300,000km/s
So on march 3 2012 time to reach earth would have been.

100,700,000 / 300,000 = ~335seconds or 5m35s

Any way far more detail can be found here.
http://deepspace.jpl.nasa.gov/dsn/faq-data.html
 
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Cosimo

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ISS Commercial Resupply Services Mission (Orb-1)

Antares/Cygnus on the pad:

1a0g.jpg


Mission overview:

http://www.orbital.com/NewsInfo/MissionUpdates/Orb-1/files/Mission Overview.pdf

Launch is at 18:10 GMT (13:10 EST) and live here:

http://www.ustream.tv/nasahdtv
 

Cosimo

Cosimo

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Glaucus said:
I thought they abandoned tonight as well due to the corona mass ejection? Or was it just last night.
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That was last night.

This is the latest statement:


January 8, 2013

Following a comprehensive review of data related to the radiation environment in space, further reviews and modeling of the rocket's avionics systems, and the forecast for favorable terrestrial weather conditions at the Wallops Island launch facility, the Antares launch team has decided to proceed forward with a launch attempt of the Orbital-1 CRS mission to the International Space Station tomorrow, January 9 pending overnight close-out of all remaining pre-launch reviews and tests.

Upon a deeper examination of the current space weather environment, Orbital's engineering team, in consultation with NASA, has determined that the risk to launch success is within acceptable limits established at the outset of the Antares program.

Tomorrow's target launch time is 1:07 p.m. (EST), which would allow the Cygnus spacecraft to rendezvous and berth with the International Space Station early Sunday morning, January 12.
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Glaucus

Glaucus

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Going to be a three part space live program in march in channel 4.

http://www.channel4.com/info/press/news/channel-4-boldly-goes-into-space
Channel 4 today announces details of its groundbreaking new Live from Space Season airing March 2014 which will culminate with a major interactive TV event featuring a live two-hour broadcast from the International Space Station (ISS) and Mission Control in Houston as the ISS completes an entire orbit of the Earth.

Head of Specialist Factual at Channel 4, David Glover, has ordered a trio of hi-spec shows, presented by Dermot O’Leary, from Arrow Media which will deliver unprecedented access to NASA and get up close and personal with astronauts like never before. In addition to the centrepiece live programme Live from Space: Lap of the Planet (w/t), Arrow Media will produce Astronauts: Living in Space (w/t) and Astronauts: Houston We Have a Problem (w/t). These two other shows will transmit on the channel during the same week and will set the backdrop and build huge anticipation leading up to main event.
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