How far could we detect a rocket in space?

  • Thread starter Thread starter GTOM
  • Start date Start date
  • Tags Tags
    Rocket Space
Click For Summary

Discussion Overview

The discussion centers on the detection of rockets in space, particularly in relation to their heat signatures and the challenges posed by background infrared radiation. Participants explore the implications of various detection methods, including radar and optical systems, and reference historical examples such as the Apollo missions and the Chelyabinsk meteor event.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question the optimism regarding the detection ranges of heat-radiating objects, suggesting that infrared background clutter may have been underestimated.
  • There is a discussion about the conditions under which objects like meteors can be detected, with some noting that they may not radiate significant heat until atmospheric entry.
  • One participant mentions the detection of Asteroid J002E3, which illustrates the complexities of identifying objects in high Earth orbit.
  • Concerns are raised about the assumptions made in the Atomic Rockets article regarding the capabilities of observation satellites and the feasibility of detecting stealthy spacecraft.
  • Participants debate the efficiency of different cooling methods for spacecraft, including the potential use of liquid helium and magnetic cooling to manage waste heat.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of current detection methods and the assumptions made in various sources. There is no consensus on the reliability of the claims made in the Atomic Rockets article, and the discussion remains unresolved regarding the best approaches to detecting rockets in space.

Contextual Notes

Limitations include the dependence on specific definitions of detection ranges, the assumptions about the visibility of heat signatures, and the unresolved technical details regarding detection methodologies.

GTOM
Messages
982
Reaction score
68
For exact example, the Apollo rocket, that carried Armstrong to the Moon?

Yes i read atomic rockets, but that happened : http://en.wikipedia.org/wiki/Chelyabinsk_meteor

It looks like to me, they were a bit over optimistic about how far can we detect a simple heat radiating object. Ok that meteor came from the direction of the Sun (isnt an impossible stealth option for a rocket neither), but still, if such faint objects can be detected only in the last few hours, that seems to me a scale below the ranges suggested by that site.
Maybe they underestimated infrared background clutter, or i misunderstood something?
 
Physics news on Phys.org
hi there

Not sure what atomic rockets has to do with it ?

dont forget it wasnt radiating any significant heat before atmospheric entry ... it seems that you think it was ?

they can only really be detected by either radar or optically

Dave
 
"dont forget it wasnt radiating any significant heat"

Does that mean it doesn't warmed up by sunlight, to a degree similar to lunar average?
With 200K i still calculated millions km detection range, based on their equitation.
 
Asteroid J002E3, detected in high Earth orbit near the L1 point (~1.5 million km), turned out to be the Apollo 12 third stage. It was rediscovered in 2003 when it re-entered Earth orbit from heliocentric orbit.
 
Remember that Atomic Rocket makes a very important(and reasonable) assumption. Any polity which can launch large spacecraft on a regular basis can afford to spread huge numbers of observation satellites throughout the solar system. We don't have very many of those right now.
 
Bandersnatch said:
He means this site: http://www.projectrho.com/public_html/rocket/
and this section in particular: http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth
There's a lot of nonsense and misinformation in that latter link.

Those telescopes could spot Voyager because the operators already knew where to look. Suppose they had no clue where to look; which is what the situation would be if one were looking for invaders. Suppose they took two seconds to take an image and only took another couple of seconds to move the telescope to the next area of the sky. Let's ignore the fact that there will have to be some overlap in images to get a full scan of the sky. How long would this full sky scan take with the Green Banks Telescope? The answer is almost a year. Not four hours.

Voyager is of course aiming it's antennas straight toward the Earth. Would intruders be broadcasting their presence and aiming their antennas straight at the place they are about to attack? No. They are not going to come in sending signals straight at us, or firing thrusters straight at us. Even if we were looking at exactly the right spot in the sky we might never see them.

Think of it this way: An alien intruder did exactly that last February over Chelyabinsk. We never saw that meteor coming. After the fact, astronomers looked at previously gathered images to see if it had ever been seen. It hadn't.
 
In Rise of Leviathan there were some stealth ships, described as strategical instead of tactical weapon.
I know that due to the laws of thermodynamics you can't contain your waste heat forever, let alone hide the flames of the thrusters. (Magnetic sails would have pretty big radar cross-section on the other hand.)

However, is that true, what is written on that not so reliable atomic rockets link?
"Furthermore, directing your waste heat (and making some part of your ship colder, a related phenomena) requires more power for the heat pump - and every W of power generated generates 4 W of waste heat."

What if they use liquid helium and magnetic cooling instead of the traditional method of compressing gases?
Would that be more efficient for containing or beaming away waste heat?
 

Similar threads

How Far Can My Model Rocket Reach in Space?
  • · Replies 2 ·
Replies
2
Views
4K
Kerbal Space Program - Rocket Design Basics
  • · Replies 2 ·
Replies
2
Views
10K
Undergrad How can we improve asteroid detection to prevent future impacts?
  • · Replies 2 ·
Replies
2
Views
3K
  • Sticky
Kerbal Space Program Tutorial Series - Open Access to 1.7
  • · Replies 48 ·
2
Replies
48
Views
69K
Should We Return to the Moon with Apollo Technology?
  • · Replies 19 ·
Replies
19
Views
7K
Undergrad Acceleration vs. uniform motion: There are three rockets in deep space
  • · Replies 11 ·
Replies
11
Views
3K
Can We Detect an Asteroid Before Impact Using Current Technology?
  • · Replies 7 ·
Replies
7
Views
3K
Graduate Stealth and detection in space: Continued
  • · Replies 7 ·
Replies
7
Views
2K
Stargazing Can distance in space be measured by human systems?
  • · Replies 22 ·
Replies
22
Views
4K
Graduate How Far Can We Detect Faint Celestial Objects Near Our Solar System?
  • · Replies 6 ·
Replies
6
Views
2K