This Week's 538 Riddle (4/15/16)

[silverscreenselect]

As a couple of people guessed, the answer to last week's riddle was 120 and 1111, and the sequence was the number 15 written in numerical form from base 15 down to base 4. The last two numbers were base 3 (120) and binary (1111).

Here is this week's riddle (from an actual NASA scientist):

You are the CEO of a space transport company in the year 2080, and your chief scientist comes in to tell you that one of your space probes has detected an alien artifact at the Jupiter Solar Lagrangian (L2) point.

You want to be the first to get to it! But you know that the story will leak soon and you only have a short time to make critical decisions. With standard technology available to anyone with a few billion dollars, a manned rocket can be quickly assembled and arrive at the artifact in 1,600 days. But with some nonstandard items you can reduce that time and beat the competition. Your accountants tell you that they can get you an immediate line of credit of $1 billion.

You can buy:

1. Big Russian engines. There are only three in the world and the Russians want $400 million for each of them. Buying one will reduce the trip time by 200 days. Buying two will allow you to split your payload and will save another 100 days.

2. NASA ion engines. There are only eight of these $140 million large-scale engines in the world. Each will consume 5,000 kilograms of xenon during the trip. There are 30,000 kg of xenon available worldwide at a price of $2,000/kg, so 5,000 kg costs $10 million. Bottom line: For each $150 million fully fueled xenon engine you buy, you can take 50 days off of the trip.

3. Light payloads. For $50 million each, you can send one of four return flight fuel tanks out ahead of the mission, using existing technology. Each time you do this, you lighten the main mission and reduce the arrival time by 25 days.

What’s your best strategy to get there first?

I assume your strategies are not mutually exclusive or the problem would take about 30 seconds to solve. So, you could buy one or two Russian engines and use the remainder to buy other materials as well.

[SpacemanSpiff]

WWDBD? (What would Dave Bowman do?)

[BackInTex]

I'm not going to try and figure it out, but I will wager part of the solution includes buying something, with leftover money, you won't use, to prevent your competitors from buying it, thus increasing their travel time.

[Bob Juch]

WWDBD? (What would Dave Bowman do?)

If you have an Amazon Echo or in a store with one, say "Alexa, open the pod bay doors." After she responds, say "Alexa, close the pod bay doors."