NASA announced yesterday that its Voyager 1 spacecraft, which blasted off in 1977 and is the farthest human-made object from Earth, had officially left the heliosphere and entered interstellar space. Cool! But the news left us with plenty of questions: What kind of data can we get from Voyager 1? How does it still have power? When will it find the aliens?
Helpfully, the scientists and engineers behind the mission answered many of these questions on Reddit yesterday. Here are our favorite moments from their AMA.
How can you still receive information from Voyager after it's gone so much further than expected?—from Reddit user cyberine
Mostly because technology on the ground has improved tremendously over the last decades, so it's possible to catch tiny radio signals from a very far distance.
What establishes the distinction between interstellar space and space considered to belong to our solar system?—from Reddit user diMario
This is not at all obvious... we're still trying to work this out ourselves. We are currently going with the particle and plasma based definition. Voyager 1 is currently surrounded by particles that came from other stars, not from our sun. Before it crossed it was surrounded by material from the sun. Other definitions have included requirements on changes in magnetic field orientation.
Is Voyager still able to capture and send photos back to Earth? —from Reddit user Eluveitie
The Voyager cameras were turned off after the image of the Pale Blue Dot Valentines Day 1990.
Why was that? Too much power usage?—from Reddit user OG-panda
The cameras were turned off to save power and memory for the instruments expected to detect the new charged particle environment of interstellar space. The computers on the ground that understand the software and analyze the images do not exist anymore. The cameras and their heaters have also been exposed for years to the very cold conditions at the deep reaches of our solar system. Even if mission managers recreated the computers on the ground, reloaded the software onto the spacecraft and were able to turn the cameras back on, it is not clear that they would work.
How long does it take to receive signals from Voyager now?—from Reddit user i_attend_goat_orgies
A signal from Voyager 1, traveling at the speed of light, takes 17 hours one way to reach Earth.
What kind of data do we get from Voyager?—from Reddit user whatireallythink
The science data that Voyager returns currently breaks down into the following: energetic particle measurements from two instruments (LECP and CRS), magnetometer data from the MAG team, radio plasma wave data from the PWS team, plasma data (on Voyager 2) from the PLS team, and ultra violet spectrum measurements from the UVS instrument (currently responding to penetrating particles).
What does the data from Voyager look like when it is first received?—from Reddit user music99
It consists of 0's and 1's. Yes, there is (old) hardware and software that extracts data from the instruments. The instrument teams have their analysis software to apply the calibrations and other corrections that turn the raw data into scientific quantities.
How long will it take for the power to run out?—from Reddit user 10247bro
We have power to run the spacecraft and all the science instruments until 2020. At that time we start science instrument shutdown and about 2025 the last instrument will be shutdown. An engineering only mission is possible 2036.
What kinds of data do you hope to see in Voyager's remaining years?—from Reddit user goblynn
A lot of Galactic Cosmic Rays (ACRs) and the galactic magnetic field, and maybe, plasma waves. As long as Voyager's nuclear batteries last, we can communicate, probably around 2025. After that there will be silence!
Once the Voyagers run out of power and stop transmitting, will we still be able to detect them?—from Reddit user IdolRevolver
Afraid not. No signal from the spacecraft really means no signal.
Can Voyager be said to drift indefinitely?—from Reddit user replicasex
The current velocity of 38,000 MPH will not change. It will go forever.
What else in the universe lies along its current trajectory and how far away is it?—from Reddit user just_foo
Voyager 1 will leave the solar system aiming toward the constellation Ophiuchus. In the year 40,272 AD, Voyager 1 will come within 1.7 light years of an obscure star in the constellation Ursa Minor (the Little Bear or Little Dipper) called AC+79 3888.
How does the processor and memory of Voyager I compare to the average modern smartphone?—from Reddit user jjlava
It's 270,000 times less memory and no real processor in the modern sense.
Do you have an official brief or Standard Operating Procedure if you pick up unmistakable signs of alien life?—from Reddit user BrettW-CD
There is no mention in the Science Mission Directorate' management handbook. :)
Thanks to the following scientists for their great AMA: Ed Stone, Voyager's project scientist; Arik Posner, Voyager's program scientist; Tom Krimigis, Voyager's low-energy charged particle principal investigator; Matt Hill, Voyager's low-energy charged particle science team member; Bill Kurth, Voyager plasma wave co-investigator; and Enrique Medina, Voyager guidance and control engineer.