# All Questions

10,672 questions
844 views

### Day versus night launches

Most launches that I've seen have occurred during the day. But I've also seen a couple of missions that have been launched at night. Are there any specific advantages or disadvantages to a day launch ...
542 views

### Why could the Lunar Ascent Engine be used only once?

The Lunar Ascent Engine was used during the Apollo missions to ascent from the lunar surface back to the Command and Service Module. There was one risky aspect of that engine: it was not possible to ...
3k views

### Was it really necessary for the Lunar Module to have 2 stages?

We all know the 2 stages LM design used by Grumman was intended to discard the mass of the landing gear (+ other components) at the moment of launching off the Moon surface to reach back the Service ...
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### Why was the Saturn V considered to be human-rated after Apollo 6?

Apollo 6 (AS-502) was the second flight of the Saturn V (the first having been Apollo 4/AS-501, five months earlier), the last flight of a Block I CSM,1 and the last unmanned Apollo mission (if one ...
457 views

### Why the thermal imaging of Mercury's surface requires a telescope on a jet flying through an eclipse?

The NASA News Feature Chasing the Total Solar Eclipse from NASA’s WB-57F Jets describes two telescope-equipped NASA jets that will fly fast enough to spend about 7 minutes in the Umbra (totality) of ...
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### Is the newly discovered exoplanet 'Teegarden b' habitable?

A new exoplanet has been just discovered around the star Teegarden, at only 12 light years away.
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### How microgravity in space affects body parts

There are things that naturally face downwards, like hands. How would they be affected in space microgravity? Would they rise or point downwards?
452 views

### Why did Apollo have a crew of 3?

Why did Apollo have a crew of three when only two actually reached the surface of the moon? I can see it makes sense for the Lunar Module only to seat two astronauts. Less mass to land softly on the ...
11 views

### Can astronomy use the black hole at the center of the Milly way as true south on a space compass?

Can astronomy use the black hole at the center of the Milly way as true south on a space compass? As far as space travel is concerned they claim to not use any space compass. Would this be a good ...
11k views

### Why didn't the Space Shuttle have a launch escape system?

Since the very beginning of space exploration, rockets had some sort of Launch Escape System (LES). From this Wikipedia article, we know that Mercury and Apollo had an escape tower, while Vostok and ...
7 views

### Undisturbed planetary alignment after galactic collision [on hold]

How do planets still orbit around the empty space where a black hole was after a black hole takes it and keeps moving through space without disturbing surrounding planets that where orbiting that ...
31 views

### Space Shuttle Moon Mission? [duplicate]

Theoretically speaking, could the shuttle have performed TLI, LOI, and TEI burns given extra OMS fuel? approximately how much fuel and payload bay space/mass would this take up and might there ...
23 views

### Recalculate Orbital Elements after a ΔV

I would like to write a program able to simulate a keplerian orbite given an initial position and velocity (r0, v0) and able to manage accelerations in different directions. To simulate the orbite, I ...
2k views

### What's inside NASA N911 Shuttle Carrier Aircraft (SCA 747)?

The Wikipedia article mentions that NASA's Boeing 747 Shuttle Carrier Aircraft (SCA 747) have the upstairs first class seating, and the rest of the plane was stripped bare. It doesn't mention ...
102 views

### Why was Apollo 17 considered to have “achieved a very successful geological survey”?

They listed out all the apollo missions, with blurbs about what the outcomes were, for example here's 15, 16 and 17: 15 - Landed on moon and deployed lunar rover. 16 - Landed on moon and deployed ...
70 views

### What Gravity does the Sun affect items with at the distance of 1 AU?

At the surface of the Earth, the force of gravity is defined as 1 G. I am wondering what gravitational force the sun excerts at the distance of 1 AU (the distance Earth is at). Imagine it like this; ...
1k views

### What was the Shuttle Carrier Aircraft escape tunnel?

The Wikipedia article for the Shuttle Carrier Aircraft mentions an escape tunnel: The avionics and engines were also upgraded, and an escape tunnel system similar to that used on Boeing's first 747 ...
2k views

### Why does the Saturn V have standalone inter-stage rings?

Why are they not integral to the lower stages, e.g. like the Falcon 9? This applies not only to the ring between the first and second stage and also to the shoulder between the second and third stage.
60 views

### Launch Azimuth for Southeast launches

I've got the formula for launching to space going Northeast as $$\cos(inc) = \cos(lat) \sin(az)$$ and that works great but what if I wanted to go southeast? For example, I know that from a ...
165 views

### Why is multi-spool pump very rare on rockets?

The only one I know of is the LP LOX pump on RD-0120. A multi-spool design is already a default for jet engines, which are basically turbine-driven air pumps. A multi-spool pump can save at least the ...
85 views

### Are Lagrangian points associated only with the smaller body?

Diagrams of Lagrangian points I've seen always show the points near the smaller object, following its orbit about the larger one. For instance: from Wikipedia. But in fact the smaller object ...
51 views

### How to become an astronaut?

I am a pure/applied mathematics student at Tehran University. About 2 or 3 years later I will get my bachelor's degree and start studying master's in applied math or theoretical physics. And maybe I ...
2k views

### What is “propulsive passivation” and why will the SpaceX STP-2 mission do it?

The Teslarati article SpaceX’s Falcon Heavy flies a complex mission for the Air Force in launch video discusses the upcoming third Falcon Heavy mission STP-2 and quotes the caption on the linked ...
95 views

### Help understanding exactly how an atomic clock facilitates “self-driving spacecraft” when paired with an onboard camera?

The TechCrunch article NASA details Deep Space Atomic Clock and other tests launching on SpaceX Falcon Heavy says: Jill Seubert, Deep Space Navigator for NASA, explained that this is the world’s ...
165 views

### How does methane waste produced by the ISS interact with our Atmosphere?

The ISS uses a Sabatier reactor to recover oxygen from carbon dioxide. This has an output product of methane. I would imagine that most methane that enters our atmosphere at ground level only reaches ...
256 views

### Why did the ullage motors for the S-IVB TLI burn shut down prior to S-IVB ignition?

I found "Technical Information Summary AS-501: Apollo Saturn V Flight Vehicle" when looking for info about the Saturn V staging sequence. It contains a nice diagram on pages 14-16 showing the various ...
4k views

### How did the Vostok ejection seat safely eject an astronaut from a sealed space capsule?

Wikipedia's Yuri Gagarin says: At about 23,000 feet (7,000 m), Gagarin ejected from the descending capsule as planned and landed using a parachute. and the section Vostok_programme; Vostok 3KA ...
1k views

### Is the “Mars blue dune” actually blue? And what makes it so?

NASA recently released an image of a blue dune on Mars. The accompanying story seems to suggest to me that it is a false color image - some property of that part of the image is detected and rendered ...
134 views

### Where are the Apollo forward heat shields currently located?

The Apollo Experience Report: Thermal Protection Subsystem explains that there are three sections to the Apollo heat shield: The aft heat shield, at the "base" of the cone and adjacent to the SM. ...
506 views

### Would it be possible for SpaceX's BFR to return the Hubble Space Telescope to Earth in the future?

Ever since the Space Shuttle retired, there was an unpopular decision to leave the Hubble Space Telescope until it eventually stopped working, since there was going to be no way to return it to Earth. ...
176 views

### Why does the Falcon 9 launch heavier payload in LEO than Ariane V and the other way around for GTO?

Browsing a comparison of orbital launch systems on wikipedia, I notice that launcher capable of launching payload in GTO can launch in GTO approximately all the mass of the payload they can launch in ...
59 views

### Did the heat shield of the Vostok 1 capsule ablate during reentry?

This Wikipedia article (in german) has some information about the heat shield of Vostok 1. The heat shield was made from asbestos, its thickness was increased from 3 cm to up to 18 cm. The weight of ...
71 views

### What was the exact nature of the observations of “solar flare activity” that delayed the launch of Vostok 5?

The interesting story of Vostok 5 recounted in Encyclopedia Astronautica's Vostok 5 (linked in comments below this answer) includes the following passage: Vostok 5 was originally planned to go for ...
44 views

### How accurate can a point in space be determined by the likes of the ICRF?

How accurately could a 3D point in open space (i.e. not on an object), say at an elevation of 30,000m above sea level, be located or modelled using the likes of the International Celestial Reference ...
63 views

### How much did it cost to refurbish the Launch Complex 39 hardware after an Apollo Saturn V launch?

A launch pad used for a rocket of some 30-35 MNewtons of thrust does not come out of it unscathed. It must be refurbished before it can be used again. How much does that cost? As an indication of such ...
30 views

### How can I calculate the azimuth from an earth station to a satellite

I have computed the ecef coordinates of both the user location on the ground, the satellite's ecef coordinates, as well as other inputs such as altitude, lat, long of both satellite and earth station....
52 views

### Why a polar orbit for TWINKLE?

TWINKLE will use a 0.45 meter telescope to record spectra of stars transited by their exoplanets. By looking at tiny changes in the spectrum as the planet's atmosphere moves in front of the star, they ...
1k views

### How exactly were solid-fuel rockets added to the parachute lines of the Voskhod capsule?

This answer notes that Voskhod: ...added a small solid-fuel rocket to the parachute lines. It fired as the descent module neared touchdown, providing a softer landing. How exactly did they safely ...
71 views

### Why was the Communications Carrier Assembly black and white?

I understand the CCA, the headset for NASA astronauts, was made up of lycra and teflon fabrics. Is there a reason, relevant to space flight, that the two materials were different colors?
85 views

### What's this mini-cupola-looking object in this photo from the ISS?

(I went through this exercise for my own benefit, so I figured I'd post it) Recently stay-extended astronaut Christina Hammock Koch posted this image to Facebook today and the object indicated by the ...
194 views

### When did soviet capsules begin using retropropulsion immediately before landing?

Wikipedia's Yuri Gagarin says: At about 23,000 feet (7,000 m), Gagarin ejected from the descending capsule as planned and landed using a parachute. and the section Vostok_programme; Vostok 3KA ...
37 views

### Noise inside an ACES/pumpkin suit helmet?

As I understand it there was plenty of noise inside a NASA EVA suit helmet from fans circulating the air. Was the Advanced Crew Escape Suit helmet for launch and reentry similarly noisy?
2k views

### Oberth effect for Earth vehicles

I don't understand this and must ask a probably very stoopid question here: The Oberth effect says that a rocket is much more efficient when (and in the orbital direction of) a payload when it ...
106 views

### Would SpaceX's Starlink constellation contribute inordinately to space debris?

I mean they already launched a large constellation of 60 satellites and have plans to launch many more; won't all this contribute inordinately to existing space junk, which is actually becoming a real ...
196 views
+100

### Will the real Snoopy please stand up?${}^†$ Has the candidate object for Apollo 10 lunar module been publicly identified?

This tweet seems to suggest that the details will be released only after a mission is planned and funder, or at least \$50 million is put in escrow, or a bitcoin wallet is offered, but I am not sure I ...
3k views

### What preparations would Hubble have needed to return in a Shuttle?

This answer states that the Hubble Space Telescope was originally intended to be returned to Earth in a Shuttle. (from shuttle manifest published immediately before the Columbia failure, showing the ...
182 views

### Remaining fuel estimation/measuring Strategy in a spacecraft

During descent of a spacecraft to any planetary body the spacecraft uses retro engine with variable throttle to reduce the vehicle velocity to zero at touchdown. Inorder to compute for the amount of ...
135 views

Today's Teslarati article SpaceX wants to offer Starlink internet to consumers after just six launches talks about the new website https://www.starlink.com/ shows several images from it, and tries to ...
71 views
+100

### How to use “patch points” to make a continuous halo orbit?

update: I've found "patch points" mentioned throughout the following papers; it is likely that an answer can be found from these sources. Targeting Cislunar Near Rectilinear Halo Orbits for Human ...