The distance from earth to sun is higher than that to Mars. It takes 8 minutes to suns light to reach earth. Why then signal takes 13 minutes to reach earth? Orbital distance is lower. Orbits are different. Both travel at the speed of light, it takes 13 minutes for us to send a signal and get a signal back, it goes both ways so it takes a while. To just send a signal there, it takes 6 minutes and 30 seconds. No, all waves travel at the same speed. It takes light eight minutes on a one way trip, 16 minutes on a two way trip.
Please learn to into physics. Easiest to think of them as waves while they are traveling, but particles when they strike something. And those numbers only apply to light traveling in vacuum. Light passing through matter travels measurably slower. Allow me to quote directly from the article you just read since you seem to have missed it. The time from Earth to Mars varies between 4 and 24 minutes because earth and mars are both orbiting the sun, not each other.
The distance between them therefore can change quite dramatically depending on where we are in our respective orbits. When Mars is directly behind Earth at the closest possible point, it is only four minutes away. When it is at the farthes point opposite us behind the Sun, it is 24 minutes away. The Sun meanwhile, which we orbit, remains at roughly 8 minutes away since our orbit around the Sun is very nearly circular.
Just came across this: Radio signals are electromagnetic waves, such as light or X-ray. In order to calculate the time of travel with this speed from Earth to Mars, we need to know the distance.
When the Mars and the Earth are at the opposite sides of the Sun, the distance is the largest: approximately: million km.
The time needed for an electromagnetic wave to cover this distance is approximately: 21 minute. So the time of travel between Earth and Mars is between 4. Shab, you are calculating as if it is 2D plane, while DoctorZuber already mentioned the earth and mars elipses are of different plane. So when Mars is at the exact opposite of Earth and the Sun is directly in between. Would it be possible for radio to even transmit to Earth Via right thru the sun?
However, since the spacecraft is moving away from or towards us, this frequency is being Doppler shifted to a different frequency. So, engineers or, more accurately, computers compare the received frequency with the emitted frequency to get the Doppler shift. It's then straightforward to find the velocity that would cause the resulting Doppler shift.
Ranging is sending a code to the spacecraft, having the spacecraft receive that code and immediately send it back out the spacecraft's own antenna, and finally receiving that code back on Earth.
The time between sending the code and receiving the code, minus the delay in turning the signal around on the spacecraft, is twice the light time to the spacecraft. So that time, divided by two and multiplied by the speed of light, is the distance from the DSN station to the spacecraft.
This distance is accurate to about five to ten meters feet , even though the spacecraft may be billion meters away! Delta DOR is similar to ranging, but it also takes in a third signal from a naturally occurring radio source in space, such as a quasar, and this additional source helps scientists and engineers gain a more accurate location of the spacecraft. Quasars are a few billion light years away and a few billion years in the past.
Quasars are used as extremely well known positions in the sky to provide a calibration for the same measurements made within a few tens of minutes of each other on a spacecraft.
Being able to do quasar and spacecraft ranging near the same time and subtracting the answers cancels a lot of errors that are the same in both measurements from the atmosphere and the equipment. The "ranging" is not really ranging, but differenced ranging. What is measured is the difference in the distance to the source between two complexes on Earth for example, Goldstone and Madrid or Goldstone and Canberra.
From that an angle in the sky can be determined relative to the stations. The angle for the quasar is subtracted from the angle of the spacecraft, giving the angular separation of the quasar and the spacecraft. That angle is accurate to about five to ten nanoradians, which means when the spacecraft is near Mars, say million kilometers away, it can determine the position of the spacecraft to within one kilometer 0.
During the entry, descent and landing phase of the Mars Exploration Rover mission, engineers listened anxiously for distinct tones that indicated when steps in the process were activated; one sound indicated the parachute deployed, while another signaled that the airbags had inflated. These sounds were a series of basic, special individual radio tones. Light speed radio communication between Earth and the Moon isn't so bad, but using it to video chat with Martian astronauts is going to be tough, even when Mars is closest to Earth.
The DSN consists of three deep-space communications facilities placed approximately degrees apart around the world, at Goldstone, California; near Madrid, Spain and near Canberra, Australia. According to a report in Business Insider , if mission controllers want to send a command to a robot on the marsh, the DNS antenna beams it across space to Marsh-orbiting satellites which direct it to the surface. However, the agency plans to upgrade the space-laser communication by the time it launches its first astronauts to Mars.
NASA wants to make use of lasers which can transmit data at 10 to times the rate of radio waves. The space agency is set to launch new satellites to try out space-laser communications in Earth's orbit in Next-gen communications using lasers has the potential to increase the data rate of communication between Earth, Mars and all future space missions. It will help on Earth too. How does our communication with space work now, and how do we need to improve it? The innovation created by sending people and things to space means that scientific instruments are constantly pushing the boundaries of technology.
Right now, it is sent to Earth through radio waves. At the moment, communicating via radio frequency limits this data rate, meaning a lot of valuable information is never transmitted back to Earth.
Sometimes we have to wait for missions or astronauts to return to Earth with data on physical storage devices to ensure we can preserve it. By moving to optical communication using lasers the data rate can be increased, similarly to how global fibre-optic networks have allowed us to constantly increase our networking speeds on Earth.
How common is this technology now, and how hard will it be to get in into space?
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