Hot answers tagged

222 votes
Accepted

How many extraterrestrial bodies have hosted a "lander" which returned images?

To be honest, I don't know how to measure atmospheric pressure, so I cannot discriminate on that basis. Initially my answer only included unmanned missions, but based on suggestions I've decided to ...
user avatar
  • 7,084
105 votes
Accepted

Why do most space probes survive for far longer than they were designed for?

Very good question! The answer boils down to statistics of failure. Some aspects involve the statistics of "random" failures—for some reason some critical component just bites the dust—and some ...
user avatar
70 votes

Have we attempted to experimentally confirm gravitational time dilation?

You don't need a space probe. Or an aircraft. Or even a car. NIST has measured the predicted general relativity time dilation due to a change in altitude on Earth of one foot!
user avatar
  • 57.7k
59 votes
Accepted

Why is it hard to take a high quality image of far away objects (like Pluto) using a high-tech space telescope?

I think a lot of folks see these gorgeous photos of distant galaxies, with fine detail on dust lanes and spiral arms and assume that since they’re so far away, seeing Pluto would be easy. But while ...
user avatar
  • 5,772
57 votes
Accepted

Why do deep space probes have to be sterilized?

Tardigrades can survive vacuum, low temperatures, and moderate radiation for quite a while. They're multicelled organisms. How tough is the toughest hypothetically viable single-celled extremophile? ...
user avatar
  • 4,526
56 votes
Accepted

Why is tantalum being used for the Hayabusa bullets?

The main reason for using tantalum is the fact that it is a rare element. When they capture the debris thrown up by the bullet, the fact that the bullet itself is tantalum makes it easy to distinguish ...
user avatar
  • 1,164
52 votes

Have we attempted to experimentally confirm gravitational time dilation?

In addition to specific probes like the one mentioned by called2voyage, the effect is significant enough that it affects everyday operations. For example, the GPS constellation needs regular clock ...
user avatar
  • 1,491
51 votes
Accepted

Why are probes that tend to explore outer system always launched to go outwards instead of straight upwards or downwards?

Starting out from Earth, you have the free 30 km/s from Earth's movement around the Sun, which is in the plane of the ecliptic. To get far out of the plane you either have to boost a similar amount "...
user avatar
51 votes

Why do most space probes survive for far longer than they were designed for?

There are a lot of generic answers here about spacecraft. I will try to answer the question specifically for Spirit and Opportunity. 90 sols was deemed sufficient to conduct the primary mission of ...
user avatar
  • 57.7k
50 votes
Accepted

How does a space probe maintain its trajectory while passing through the extreme gravitational field of the gas giants of our solar system?

The trajectory was not only "unhindered" - it was enhanced! Knowing mass of the planet you can calculate very precisely how the trajectory of a probe flying by will be affected. You modify the ...
user avatar
  • 52.6k
48 votes
Accepted

How much more expensive are scientific instruments for space use?

Preface: I am far, far from an expert in space electronics; I don't think I can weigh in on how much these sensors actually are, which is the title question; all I can offer is an uneducated inane ...
user avatar
  • 2,144
48 votes
Accepted

What are the teeth on the edge of Venera 13 and 14?

The teeth served an aerodynamic function. ...metal teeth were added to the periphery of the impact ring in an effort to reduce the spin and oscillation during the descent and prevent the rough ...
user avatar
47 votes
Accepted

When will we send floating probes to Venus?

When will we send? We already did. In 1985 and 1986 the Soviet Union sent two Vega probes to Venus. Both included a robotic balloon (usually called aerobots). The two balloon aerobots were ...
user avatar
  • 920
41 votes
Accepted

Why don't we launch spacecraft from the Moon?

First a few terms: Low Earth Orbit (LEO) All spacecraft must first achieve low Earth orbit. This is true whether you're sending stuff to the Moon or Mars. Trans Mars Insertion (TMI) The burn needed ...
user avatar
  • 15.2k
40 votes

Why is it hard to take a high quality image of far away objects (like Pluto) using a high-tech space telescope?

Distance. Size of the target. Its poor albedo at such distance to its only source of illumination, the Sun, compared to closer celestial bodies. And movement of the target and the vantage point in ...
user avatar
  • 75.6k
40 votes

Have we attempted to experimentally confirm gravitational time dilation?

Yes, time dilation was experimentally confirmed by Gravity Probe A, launched by NASA on June 18, 1976. The clock rates of two masers (one on the probe and one on Earth) were compared, and it was ...
user avatar
  • 23.6k
39 votes

Why are probes that tend to explore outer system always launched to go outwards instead of straight upwards or downwards?

We've had 5 flyby missions to the outer solar system so far. All of them had primary missions at one or more planets. That set the main constraints for their trajectories. Anything after the last ...
user avatar
  • 122k
38 votes

Is it possible to create a relativistic space probe going at least 0.1c with present day technology?

I'm showing the calculations for Russell Borogove's excellent answer. You've asked to accelerate an object to 0.1 times the speed of light. Mathematically, $$\left( \frac{\Delta v}{c} \right) = 0.1$$...
user avatar
  • 46.6k
37 votes
Accepted

Requirements to orbit Pluto

This mission study came up with a 900 kg nuclear-electric-propulsion spacecraft launched on an Ariane V with a C3 of 100 km2/s2 and a Jupiter gravity assist along the way. 1.05 kW electrical power at ...
user avatar
  • 57.7k
37 votes

Could one of the interstellar probes discover Planet IX by accident?

Any hypothetical planet (or other object) even further out would be very dark, so few photos are taken for any reason other than to look inward. (And in any case, the cameras on the Voyagers are shut ...
user avatar
35 votes

When will we send floating probes to Venus?

Why are people so fascinated about Mars and not about Venus at all? The trivial answer - Mars is moderate place. A human could easily get around with a spacesuit, and it is trivial for robots and ...
user avatar
  • 1,604
35 votes
Accepted

Is it possible to create a relativistic space probe going at least 0.1c with present day technology?

No. 10% of the speed of light is about 30,000,000 m/s. Our fastest space probe to date, New Horizons, left Earth at less than 1/1000 of that speed. With a large propellant tank and a high-efficiency ...
user avatar
33 votes

Has any object launched from Earth gone into the Sun?

No, not yet. The Parker Solar Probe became the closest ever artificial object to the sun on October 29th, 2018, surpassing Helios 2 which held the record since 1975 [1]. No other human-made object ...
user avatar
  • 6,800
29 votes

How much more expensive are scientific instruments for space use?

I'll chime in with the other two well-stated answers. In addition to all the testing, there is the issue of "What do you do when the instrument fails a test?" Most COTS (Commercial Off-The-Shelf) ...
user avatar
29 votes

Why are probes that tend to explore outer system always launched to go outwards instead of straight upwards or downwards?

It is important to realize that space probes aren't really useful for finding objects in deep space. Space is so empty that a probe sent in a random "exploratory" direction would have a negligible ...
user avatar
  • 7,013
28 votes
Accepted

What powers New Horizons?

Space is basically a vacuum, so there's no air resistance. A probe that's been launched will travel at the same speed indefinitely. Because New Horizons is moving away from the Sun, it loses some ...
user avatar
  • 122k
28 votes

Is it possible to create a relativistic space probe going at least 0.1c with present day technology?

Breakthrough Starshot claims to be capable of attaining 0.15c to 0.2c. But, the concept is based on a swarm of tiny probes (centimeter scale). They would be propelled by a "ground-based" laser; no on-...
user avatar
  • 17.1k
27 votes
Accepted

Dawn Spacecraft: Why are the orbits so high?

Its final orbit will only be 375 km above Ceres, but you have to give it time. Dawn is powered by xenon ion engines, which are extremely efficient, but very weak. The usual comparison is that they ...
user avatar
  • 20.9k
27 votes

Why do deep space probes have to be sterilized?

So back in the summer of 1935, some folks down in Australia were having problems with a beetle's larvae that were nomming on the sugar cane roots and harming crops. Since traditional methods of ...
user avatar
  • 371
27 votes

What is the rarest launch window?

Comet West with its unpredictable but estimated at 558 000 years period is a good contender. Since launch windows can aim for the alignment of N objects, the answer obviously tend to infinity. You ...
user avatar
  • 12.2k

Only top scored, non community-wiki answers of a minimum length are eligible