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67 votes
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Are there any space probes or landers which regained communication after being lost?

Well, it is very common indeed to regain communications with a space probe after losing contact. In fact, communications are generally not continuous for the entirety of any mission. These are ...
Swike's user avatar
  • 2,501
54 votes

ELI5: Why do they say that Israel would have been the fourth country to land a spacecraft on the Moon and why do they call it low cost?

Chandrayaan-1 hit the Moon at high speed and did not survive its "landing", which would have been much more difficult to engineer. (Its successor, Chandrayaan-2, which will actually land, is expected ...
Nathan Tuggy's user avatar
  • 4,567
50 votes
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Why do we need to make probes land on other planets or moons?

You can always learn more by a closer inspection. You may read articles about materials being detected by spectrometry from orbit, but don't let that give you the impression that humans have the ...
Mark Foskey's user avatar
23 votes
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Why do the more recent landers across Mars and Moon not use the cushion approach?

Propulsive landing is now a proven technology and a factor of 1,000 more accurate. According to NASA Facts; Mars Exploration Rover: With the heat-shield portion of the aeroshell pointed forward, the ...
uhoh's user avatar
  • 149k
20 votes

Are there any space probes or landers which regained communication after being lost?

Are there any space probes\landers which regain communication after being lost? IMAGE Contact was lost with IMAGE on December 18, 2005, 07:39 UTC and it was ...
uhoh's user avatar
  • 149k
17 votes

How did sulphur come up to the surface of the moon?

The moon's composition is largely similar to the earth's crust, the earth's crust contains plenty of sulphur and sulphur compounds too. My guess on other missions is they either weren't looking for it ...
Alan Birtles's user avatar
  • 2,066
16 votes
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Why would thermal imaging be used to locate the Chandrayaan-2 lander?

It was not a thermal image at all. It is an optical image that has been captured by Orbiter of the lander spot and not thermal image as reported by others media houses. OHRC is same like our ...
jkavalik's user avatar
  • 5,128
16 votes

Why do the more recent landers across Mars and Moon not use the cushion approach?

The 2007 paper The challenges of landing on Mars gives a decent introduction to the subject, and the evolution of Mars landing methods. First generation: Viking. Propulsive landing, lander on legs. ...
Hobbes's user avatar
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13 votes
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Chandrayaan 2: Why is Vikram Lander's life limited to 14 Days?

Orbiting satellites can still have problems with eclipses, from loss of both power and heat but the total time is normally measured in minutes so simply having enough battery power to keep electronics ...
GremlinWranger's user avatar
13 votes

Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

The explanation has to do with the operation of the radar transmitters and the round trip light travel time. It takes about 3 seconds for a radar pulse to travel from the Earth to the Moon and back. ...
Joseph Lazio's user avatar
12 votes
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Are low, polar lunar orbits in general relatively stable?

LRO was inserted into a polar frozen orbit for commissioning, which required no stationkeeping. This orbit was a stable 31.5 km x 199 km polar orbit with periapsis over the South Pole. By "frozen" ...
Diane's user avatar
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12 votes
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Is there any way to determine the fate of Chandrayaan-2?

I think a somewhat reasonable first-order analysis would look at the fates of similar hard impact failures on the moon and in deep space. The most immediately relevant is the failure of Israel's ...
mothman's user avatar
  • 968
10 votes

Why is the Duration of Time spent in the Dayside greater than that of the Night side of the Moon for Chandrayaan-2 Orbiter?

The degree of orbital shadowing experienced by an orbiting object with small orbital altitude is determined by its beta angle (normally used in reference to LEO objects but the concept applies to ...
Organic Marble's user avatar
9 votes
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Did the cold temperature of the lunar south pole cause Chandrayaan-2's on board electronics to fail?

Did the cold temperature of the lunar south pole cause Chandrayaan-2's on board electronics to fail? tl;dr: Probably not, the spacecraft was likely in sunshine at the time, and would have also been ...
uhoh's user avatar
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8 votes
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Why is the Chandrayaan lunar insertion so long?

It didn't have enough thrust. Small rocket engines are easier to build than large ones, and weigh a lot less. That probe (I assume you mean Chandrayaan 1) had a 440 N main thruster that it used to ...
Michael Stachowsky's user avatar
7 votes
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Chandrayaan 2: How has life of the orbiter increased from 1 year to more than 7 years?

How has life of the orbiter increased from 1 year to more than 7 years? The stated one year operational period represented the pre-mission plan. That pre-mission plan had to provide enough delta V to ...
David Hammen's user avatar
7 votes

Why is the Duration of Time spent in the Dayside greater than that of the Night side of the Moon for Chandrayaan-2 Orbiter?

There is no circular orbit that has a share of 50:50 between night and day. The possible times are a bit less than 50% to 0% night or, respectively, a bit more than 50% day to 100% day. The two ...
asdfex's user avatar
  • 15.1k
6 votes

What are the operating systems and network stack in the Chandrayaan - 2 vehicles?

For the embedded software, likely Ada An ISRO scientist working out of the Atmospheric and Oceanic Sciences group gave some insight that his part of ISRO mostly works with FORTRAN, MATLAB and Python ...
Adam Coville's user avatar
6 votes

Why would thermal imaging be used to locate the Chandrayaan-2 lander?

Thanks to @jkavalik for the informative answer and helpful links! As is pointed out there, there seems to be an abundance of false social media accounts claiming to be K. Silvan. From today's Sep 09, ...
uhoh's user avatar
  • 149k
6 votes

Chandrayaan landing ellipse size and rationale

While I don't know why they chose such tight landing target but we know that while the landing box for Chandrayaan-2 Vikram lander was 500×500 meters the exact spot they were aiming for was even ...
Ohsin's user avatar
  • 1,812
5 votes

Why is the Duration of Time spent in the Dayside greater than that of the Night side of the Moon for Chandrayaan-2 Orbiter?

It all depends on how you define "dayside" and "nightside", and how you define "entering" or "exiting" either one of them for a satellite. I suppose a big part of the confusion comes from this ...
Mike Nakis's user avatar
5 votes

Are there any space probes or landers which regained communication after being lost?

Not meeting the criteria of the question but there is day probe from Pioneer which was not intended to survive but continued to operate for 45 minutes after impact. A number of other probes have lost ...
GremlinWranger's user avatar
5 votes
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How will Chandrayaan-2 reach a polar orbit?

It will be a combination of things. Like TonyK mentioned in his comments, most of the change will occur during cis-lunar transfer. This is optimal because inter-planetary trajectories can be designed ...
aaastro's user avatar
  • 478
5 votes

Comparing Japan's SLIM and India's Chandrayaan-3 trajectories

Here's a quick answer, the orbital mechanics and astrodynamicists here may offer a more quantitative analysis. tl;dr: to get captured into a lunar orbit, you have to do two things - get near the Moon ...
uhoh's user avatar
  • 149k
4 votes

Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

I know nothing of the activity you're asking about, but I do know something about radar. All the radar systems I've worked with used a single antenna to both transmit and receive. The power of the ...
Steve's user avatar
  • 1,174
4 votes

Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

Since the deep space network can perform ranging on spacecraft much farther away (tens of thousands of times farther than the moon) by itself, why was it necessary to use a non-colocated, non-DSN dish ...
Hobbes's user avatar
  • 128k
4 votes

Are there any space probes or landers which regained communication after being lost?

Need to mention Akatsuki probe, which lost contact for an hour instead of 20 minutes entering Venus orbit in 2010. This incident led to five year delay in achieving destination.
Ivan Borsuk's user avatar
4 votes
Accepted

How did sulphur come up to the surface of the moon?

Sulfur on the Moon's surface may have come from volcanic activity, and it was found in Apollo rock samples in 2020 a few years before Chandrayaan-3 arrived. While most of this volcanic activity took ...
Oscar Lanzi's user avatar
  • 8,525
3 votes

What does Cees Bassa's Doppler plot of Chandrayaan 2 show?

The plot shows the raw, received frequency of the signal from the spacecraft. If the output signal from the spacecraft would be of a fixed frequency, we could directly extract the relative velocity ...
asdfex's user avatar
  • 15.1k

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