Skip to main content
119 votes

Can a human land on Deimos using pressurized deodorant cans?

Deimos: radius 6.2km, mass 1.47 $\cdot$ 1015kg. Let's pick an initial circular orbit radius at a safe 8km. Orbital velocity calculator gives 3.502m/s orbital velocity. To deorbit, we'd need to drop ...
SF.'s user avatar
  • 55k
79 votes

Have spacecraft photographed each other beyond Earth orbit?

Yes, here is a picture of the Curiosity lander spacecraft taken by the Mars Reconnaissance Orbiter. The picture was taken about one minute prior to the landing of Curiosity. Image from https://www....
Organic Marble's user avatar
59 votes
Accepted

What would it take to get a message to another star?

The Arecibo raqdio telescope has a $300\ \mathrm m$ diameter mirror. Let's consider a radio wavelength of $3\ \mathrm{cm}$ ($10\ \mathrm{GHz}$) for convenience of arithmetic. That gives a diffraction ...
Steve Linton's user avatar
  • 19.6k
55 votes

Have spacecraft photographed each other beyond Earth orbit?

The Mars Odyssey orbiter was photographed by Mars Global Surveyor in 2005. https://commons.wikimedia.org/wiki/File:Mgs_odyssey.gif https://photojournal.jpl.nasa.gov/catalog/PIA07941 Figure 1: Why ...
Heopps's user avatar
  • 9,061
50 votes
Accepted

How can Trident be so inexpensive? Will it orbit Triton or just do a (slow) flyby?

I wrote the article you are referencing. @Hobbes has it exactly correct. It is a lightweight vehicle that can launch on even a small rocket, and takes advantage of gravity assists and favorable ...
David W. Brown's user avatar
42 votes
Accepted

What does NASA mean when they use the term 'PDT (ERT)'

ERT is Earth Received Time. I.e., when we find out about the event. source
Organic Marble's user avatar
34 votes

What would it take to get a message to another star?

@SteveLinton's answer is excellent and I'll just confirm below that its logic and numbers are correct. Then I'll show that you can do it optically as well, but with 10 meter telescopes instead of ...
uhoh's user avatar
  • 149k
31 votes

Have spacecraft photographed each other beyond Earth orbit?

some examples: LRO images of the Apollo landing sites. This is Apollo 11: Cassini and Huygens: this is Huygens as seen by Cassini, 12 hours after Huygens was released. Rosetta and Philae. ...
Hobbes's user avatar
  • 128k
28 votes
Accepted

How is Voyager 1 still operating?

The Voyagers have been so reliable due to careful design, plus lots of redundancy. Voyager employs three dual-redundant computer systems per spacecraft. The first, the CCS, is nearly identical to ...
Hobbes's user avatar
  • 128k
25 votes
Accepted

In deep space missions, how much of the journey is pre-programmed and how much is "direct" control?

The journey to the destination is about always completely pre-planned. All the gravity assists, close fly-bys, and so on, are planned before launch - and often long before the probe design is ...
SF.'s user avatar
  • 55k
21 votes
Accepted

How an americium-241 RTG would differ from one using plutonium-238?

Power and Mass From this paper (emphasis mine): The specific power of an 241Am-fuelled RTG cannot match that of a 238Pu system (except perhaps at small power output levels); however, the design work ...
Jack's user avatar
  • 9,956
19 votes
Accepted

How to calculate data rate of Voyager 1?

OK let's first understand units. The decibel (dB) is a base-10 log scale without units and dBm is a similar decibel scale for power referenced to 1 milliwatt. They also include a factor of 10, so for ...
uhoh's user avatar
  • 149k
18 votes

Have spacecraft photographed each other beyond Earth orbit?

For a case with more extreme relative motion than most of the other answers, the Lunar Reconnaissance Orbiter (polar orbit) imaged the LADEE orbiter (close to equatorial orbit) in 2014: The LADEE ...
R. Wagner's user avatar
  • 181
16 votes

Has an SRB been considered for use in orbit to launch to escape velocity?

This is referred to as 'kick stage' motor and is commonly used. One example being Star 37. A larger Star 48 is what sent New Horizons on the way to Pluto
kert's user avatar
  • 1,320
16 votes

How can Trident be so inexpensive? Will it orbit Triton or just do a (slow) flyby?

It's a fast flyby in the $500M cost class (a Discovery mission). So not really comparable to Beresheet. A rare, low Δv trajectory (Fig. 1) enables an MMRTG-powered spacecraft fitting under the ...
Hobbes's user avatar
  • 128k
16 votes

Have spacecraft photographed each other beyond Earth orbit?

You can also find photos of some Mars rovers from various orbiters/satellites: Opportunity from Mars Reconnaissance Orbiter After a planet-wide dust storm in June 2018 blocked the Opportunity ...
BruceWayne's user avatar
  • 1,063
15 votes

Travel Speed in Space

Currently functional and proven technology is limited to basically no interstellar travel at all. To reach one of our stellar neighbors (like Proxima Centauri), one of the fastest space probes we have ...
Dragongeek's user avatar
  • 19.1k
15 votes
Accepted

Are Zond 2 and Venera 4 basically the same spacecraft design? What were the differences?

Very short answer They are different generations of the same family of interplanetary spacecrafts. Short answer Zond 2, as well as Zond 1 and -3; and Venera 2 and -3, were interplanetary ...
Sergiy Lenzion's user avatar
14 votes
Accepted

Flying fuel tanks! Which deep-space spacecraft had the largest fuel mass fraction?

I'm not up to a complete exhaustive survey of every possible contestant, so I've focused on relatively recent orbiters. I found a few that beat Cassini. The figures I've found so far are occasionally ...
Russell Borogove's user avatar
14 votes

When was the last time that Starman/Roadster was seen?

The latest measurements used by JPL Horizons to calculate its trajectory were reported on 3/27 as follows: 2018-Mar-27: Two reporting sites (J94 & K93) extend data arc one month. That is the ...
PearsonArtPhoto's user avatar
  • 121k
14 votes
Accepted

First LED left on another planet⁺ by humans?

July 20, 1976, Mars, Viking 1 lander. In the article "Viking gas chromatograph–mass spectrometer" by Rushneck et al, Review of Scientific Instruments 49:817-834 (1978), section G (pp. 828-9) ...
Camille Goudeseune's user avatar
14 votes
Accepted

Can a human land on Deimos using pressurized deodorant cans?

I don't think you would get any significant thrust from them on Deimos. The maximum surface temperature is -4 °C (source). The boiling point of butane is -2 °C (source). I don't think the can would ...
Jesse Bugden's user avatar
13 votes
Accepted

Mass of food per astronaut per year for an extended deep space excursion?

So, after a lot of searching after what are the recommended daily intake in terms of nutrient requirements and other stuff, I used a couple of sources to make an average of what is actually needed, ...
gromain's user avatar
  • 766
13 votes
Accepted

With current state of technology if we wanted how long would it take for newly launched probe to overtake Voyagers?

With reasonably current technology there are basically three options, I think: A Jupiter gravity assist similar to how the Voyagers themselves got most of their velocity. This could do a bit more by ...
Steve Linton's user avatar
  • 19.6k
13 votes

Have solid dish antennas on deep space spacecraft (as opposed to meshes) ever provided any other helpful function? As meteor shields perhaps?

A few months before Cassini made its mission-ending dive into Saturn's atmosphere, it skirted the region between Saturn's atmosphere and the innermost ring. From NASA Spacecraft Dives Between Saturn ...
David Hammen's user avatar
  • 74.9k
12 votes

Why is the Deep Space Industries Prospector 1 using water propellant instead of hydrazine?

Unlike chemical rockets such as hydrazine (a monopropellant, which doesn't require separate oxidizer and fuel to burn), water is just the reaction mass — not the energy source. The Comet-1 ...
Nathan Tuggy's user avatar
  • 4,567
12 votes

Why doesn't thermal radio emission from a DSN "hot dish" completely swamp the benefits of a cold LNA?

Because the dish isn't a black body. At RF it has a very low emissivity, hence the name "reflector".
pericynthion's user avatar
  • 10.1k
12 votes

Why doesn't thermal radio emission from a DSN "hot dish" completely swamp the benefits of a cold LNA?

When discussing radio antennae, radio astronomers usually describe things in terms of temperatures. We can convert between power and temperature simply by multiplying (or dividing) by Boltzmann's ...
Phiteros's user avatar
  • 5,626
12 votes

Could a Falcon Heavy assembly or something similar be useful for deep space missions?

A Falcon Heavy on the launch pad masses about 1400 tons. Its payload to low orbit is about 64 tons (fully expendable) (both figures from wikipedia). So it would take, not 2, but about 22 Falcon Heavy'...
Steve Linton's user avatar
  • 19.6k
11 votes
Accepted

Could a molecular cloud be breathable?

Not a chance. Those "clouds" are a vacuum, but just a vacuum that has a few more particles than outside those "clouds". The density of those "clouds" around 1–100 particles per cm³. You can't ...
gerrit's user avatar
  • 11.7k

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