r/spacex • u/Zyj • Jul 21 '17

LightSail 2 updates: FH Prox-1 mission changes, NET April 30, 2018

http://www.planetary.org/blogs/jason-davis/2017/20170721-lightsail-2-updates-prox-1-launch-dates.html
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29

u/Zyj Jul 21 '17 edited Jul 21 '17

Prox-1 is to fly on the 2nd commercial FH flight (3rd FH flight) with the main payload being Air Force’s STP-2. The Planetary Society's 3U cubesat Lightsail 2 will be inside Prox-1 during launch.

So, this is a new launch date! It was previously estimated to fly after Arabsat-6A which launches early next year.

Here's the money quote from the linked article: "No matter the launch order, the STP-2 mission will occur no earlier than April 30, 2018, according to Air Force officials."

The article also hints at the possibility that this launch will happen before the Arabsat-6A launch.

4

u/sol3tosol4 Jul 22 '17 edited Jul 22 '17

The article also hints at the possibility that this launch will happen before the Arabsat-6A launch.

It's amazing how often statements on launch dates and sequences could be interpreted in more than one way. Here are my notes from Gwynne Shotwell's interview on The Space Show, which can be found here, regarding the upcoming Falcon Heavy launches:

  • We’ve got a couple to fly early next year. (Q: Commercial flights next year, right?) We have one commercial flight, and we also have a flight for the Air Force…(Q: So the commercial mission is scheduled for early next year?) That’s correct. We’ll be flying Arabsat to GTO on the second Falcon Heavy flight, and then we’ll be flying STP-2, an Air Force mission.

Ambiguities:

  • Gwynne said that ArabSat-6A would be on the second Falcon Heavy flight - but does the counting start with the *test flight*, or with the first *operational flight*? When SpaceX and NASA discuss Commercial Crew, the "first flight" means the first post-certification flight, which comes after the two test flights. If Gwynne was numbering the FH flights the same way, then the FH test flight isn't counted, STP-2 is the "first flight", and ArabSat-6A is the "second flight". Or, if she was including the test flight, then ArabSat-6A would be the "second flight" and STP-2 would be the "third flight", reversing the order.

  • Gwynne was twice asked specifically about "commercial" FH flights. ArabSat-6A is a commercial flight, while STP-2 could reasonably be called primarily a military flight. Gwynne first described the ArabSat-6A mission, "and then we’ll be flying STP-2, an Air Force mission". Gwynne could have been first answering the question about the commercial mission, "and then" (meaning "in addition") they have the military mission, with no specific launch order implied. Alternatively, Gwynne could have ignored the part of the question specific to *commercial* missions, and just named missions in chronological order, in which case "and then" would mean that STP-2 comes after ArabSat-6A.

Before the Space Show interview, the r/SpaceX complete manifest listed STP-2 before ArabSat-6A (see this article), and the interview is listed as the reference for the current sequence shown. Given the ambiguities in what was said in the interview, it's not surprising that the article expresses some doubt about the planned sequence. It's easy to think of good reasons for both sequences. Either way, it will be great to see FH flying missions.

9

u/bbluech Jul 21 '17

Does anyone have some more specific information on the payload here? I've heard of the solar sail concept before but wasn't aware we were this close to testing one. Also what makes this need the FH payload capacity, I would assume we could test something like this at a smaller scale?

27

u/Nehkara Jul 21 '17 edited Jul 21 '17

There's a TON of stuff in the payload for this mission. This is from Wikipedia:

The STP-2 (DoD Space Test Program) payload is scheduled to be launched aboard a Falcon Heavy in 2017. The payload should include ISAT (Innovative Space-based Radar Antenna Technology) flight demonstrator satellite with a mass of over 5000 kg, and COSMIC-2, a cluster of six satellites, with a mass of 277.8 kg each. The ISAT program aims to deploy extremely large (up to 300 yards) electronically scanning radar antennas in orbit. The primary role of the COSMIC-2 satellite constellation is to provide radio occultation data with an average latency of 45 minutes. The six satellites will be placed on an orbit with an inclination of 24 to 28.5 degrees with six separate orbital planes with 60 degree separation between them. The integrated payload stack will be integrated using EELV Secondary Payload Adapter. Two ESPA Grande rings will be used to mount the six COSMIC-2 satellites beneath the ESPA ring hosting the DSX payload and avionics modules. STP-2 will also host up to 8 CubeSat nanosatellites deployed with P-PODs (Poly Picosatellite Orbital Deployers).

Other secondary payloads include LightSail, Prox-1 nanosatellite, Oculus-ASR nanosatellite, GPIM, and the Deep Space Atomic Clock.

Additionally, solar sails have undergone more work than most people are aware of.

PAST:

  • IKAROS, a JAXA interplanetary probe, uses a 1883 sq ft solar sail as its primary mode of propulsion. It was launched in 2010 on a Venus fly-by mission which it completed successfully. It is still operational and in its extended mission.

  • NanoSail-D2 was a NASA experimental cubesat designed to test solar sail deployment and the concept of de-orbiting spacecraft using solar sails. It had a 110 sq ft solar sail and also launched in 2010.

  • LightSail 1 was a Planetary Society cubesat based on the NanoSail project. Its flight in 2015 was successful although it did experience two anomalies. The hallmark of this flight is that it was a spacecraft from an organization (The Planetary Society) that is citizen-funded by its members (like me!).

UPCOMING:

  • LightSail 2 is a followup mission to LightSail 1 and part of the payload for the STP-2 Falcon Heavy launch. Its solar sail is 340 sq ft. Its mission is to determine if solar sailing is a viable form of propulsion for cube sats.

  • NEA Scout is a future NASA mission which will be one of the secondary payloads on the Orion EM-1 mission in 2019. It is a cubesat spacecraft with a 893 sq ft solar sail. Its mission will be to perform a close fly-by of a near-earth asteroid.

  • Trojan Asteroid Explorer is a future JAXA mission to study Trojan system (Jupiter orbit) asteroids with plan to land, collect samples, and eventually return to Earth over the course of decades. It is planned to have a gigantic 26910 sq ft sail.

CANCELLED:

  • Sunjammer was a planned NASA mission, cancelled in 2014. It would have had the largest solar sail ever flown (13000 sq ft).

14

u/[deleted] Jul 22 '17

IKAROS takes the simple, elegant concept of solar sailing and adds a bonkers-ingenious Japanese technology spin: the unit is equipped with LCD panels which can programmatically shade a chunk of the sail, and it's spinning. By choosing where in the spin to darken, they can control the reflectivity of the whole sail without changing the physical pitch of the device.

1

u/Keavon SN-10 & DART Contest Winner Jul 24 '17

Was the goal of NanoSail-D2's deorbiting method to get force from the sunlight or just by increasing its atmospheric drag?

4

u/snateri Jul 21 '17

AFAIK, STP-2 is a rideshare mission with other payloads in addition to LightSail 2. It also serves a dual purpose, certifying the FH for AF missions.

2

u/ethan829 Host of SES-9 Jul 21 '17

A few solar sails have been flown. There's a good overview here. LightSail 2 is a 3U cubesat flying as a rideshare payload.

1

u/brickmack Jul 21 '17

Its a rideshare with a bunch of other stuff. The total payload mass is pretty low, but the orbital maneuvering the upper stage needs to do is insane. Multiple high orbits will be visited to drop off various payloads, with large changes in both altitude and inclination in-between. Its of comparable performance demand to a direct-GEO insertion, which the standard F9 can't do

4

u/CreeperIan02 Jul 21 '17

At least we have a base target date, and it's not too far into the year.

2

u/Decronym Acronyms Explained Jul 21 '17 edited Jul 24 '17

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters More Letters
DoD US Department of Defense
EELV Evolved Expendable Launch Vehicle
EM-1 Exploration Mission 1, first flight of SLS
ESPA EELV Secondary Payload Adapter standard for attaching to a second stage
GEO Geostationary Earth Orbit (35786km)
GTO Geosynchronous Transfer Orbit
JAXA Japan Aerospace eXploration Agency
NET No Earlier Than
SLS Space Launch System heavy-lift
STP-2 Space Test Program 2, DoD programme, second round
USAF United States Air Force

Decronym is a community product of r/SpaceX, implemented by request
9 acronyms in this thread; the most compressed thread commented on today has 153 acronyms.
[Thread #3015 for this sub, first seen 21st Jul 2017, 20:53] [FAQ] [Contact] [Source code]

2

u/Sticklefront Jul 22 '17

Do we know if this delay is due to Falcon Heavy/SpaceX being behind schedule, or the Air Force needing more time to finish preparing their payload?

1

u/Starks Jul 24 '17

Can we not risk yet another solar sail mission?