15% off membership for Easter! Learn more. Close

There is a colony of 1000 people on the moon. Estimate the bandwidth needed. How would you provide internet to them?

Asked at Google
1.2k views
Answers (1)
crownAccess expert answers by becoming a member

You'll get access to over 3,000 product manager interview questions and answers

badge Gold PM

it will be important to understand the composition of the 1000 people on Moon and what they might be using internet for. Lets assume the people in moon are self sufficient and are an organized unit i.e they have their source of power, their friends are in moon, their social circles are in moon, and they dont have anyone to contact heavily at earth. Since its a colony, it will have households with people belonging to different subsection of society i.e. Utilities, education, Food, basic service providers and Law and Order. 

Lets assume each of the groups identified have an administrator, and workers. Education will have a larger subsection of students. 

  1. Utlities - 20% * 1000 = 200
  2. Education - 30% * 1000 = 300
  3. Food - 30% * 1000 = 200
  4. Basic service providers = 10% * 1000 = 100
  5. Law & Order = 10% * 1000 = 100

So if I were to break out their jobs into low, medium, high , very high bandwidth usage

Type%% Low
100kbps%Medium
500kbps% High
2mbps% very high
>2 mpbsTotal
utilities20%25%50%20%5%0.2*1000(.25*0.1mbps + 0.5*0.5mbps + 0.2*2mbps + 0.05*4mbps) = 200*(0.025+0.25+0.4+0.2) = 0.875*200 = 175 mbps
education30%10%40%40%10%= 300* (0.01+0.02+0.8+0.4)=369mbps
Food30%10%70%10%10%= 300*(0.01+0.35+0.2+0.4) = 288 mbps
Basic Service10% 100%   = 100* 0.5 = 50mbps
Law & Order10%10%10%30%50%= 100 * (0.01+0.05+0.6+0.2) = 86 mbps

Total bandwidth needs = 968 mbps ~~ 1 GBPS

how to make internet available. 

A few things we know about Moon, it doesnt rotate at the same speed as earth does i.e. the days & nights arent evenly broken out, its not always at the same position w.r.t earth.

There are a few options

  1. Have a router provisioning internet to the colony. The router has a satelite link to a remote desktop in earth. This is how ISS gets internet. The problem here would be very slow internet.
  2. Have an LEO satelite strategically positioned on earth and a dish receiver on the colony. The problem here would be there wont be a continuous line of sight between the satelite and receiver, since 2 times a year the sun is between the earth and the moon, not to mention RF signals will be face constant interference with cosmic radiation
  3. have laser based transmission from earth to moon via an uplink. I read recently that NASA has provided a 14.1 b contract to Nokia to provide 4G connectivity in Moon
Access expert answers by becoming a member
1 like   |  
Get unlimited access for $12/month
Get access to 2,346 pm interview questions and answers to give yourself a strong edge against other candidates that are interviewing for the same position
Get access to over 238 hours of video material containing an interview prep course, recorded mock interviews by expert PMs, group practice sessions, and QAs with expert PMs
Boost your confidence in PM interviews by attending peer to peer mock interview practices, group practices, and QA sessions with expert PMs
Get unlimited access for $12/month
Get access to 2,346 pm interview questions and answers to give yourself a strong edge against other candidates that are interviewing for the same position
Get access to over 238 hours of video material containing an interview prep course, recorded mock interviews by expert PMs, group practice sessions, and QAs with expert PMs
Boost your confidence in PM interviews by attending peer to peer mock interview practices, group practices, and QA sessions with expert PMs