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Sub-rack level cargo is integrated into HTV resupply racks (HRRs). All HRRs and ISPR equivalents are integrated into the HTV Pressurized Logistics Carrier (PLC). Unpressurized cargo is integrated onto an exposed pallet and, subsequently, into the HTV Unpressurized Logistics Carrier (UPLC or ULC). It is also capable of carrying several hundred kilos of water.<\/p>\n
After the HTV has delivered cargo to the ISS, waste cargo from the ISS is loaded into the HTV; and is destroyed upon reentry into the Earth\u2019s atmosphere.<\/p>\n
This cargo capability is crucial for the Station, as managers plan out the convoy of agency and commercial cargo vehicles that will need to pick up the massive payload capability of the soon-to-retire shuttle \u2013 as much as that retirement date remains unknown.<\/p>\n
It total, the HTV debut flight will involve a mission duration of six days of rendezvous operations, 30 days of \u201cattached\u201d phase operations, followed by two to three days of departure and a disposal via re-entry.<\/p>\n
HTV Operations:<\/p>\n
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A total of 12 demonstrations of HTV capability are planned for this mission, with reviews on its performance taking place at key stages of the flight \u2013 including an Integrated Mission Management Team (MMT) meeting on Flight Day 6, which will result in approval for the HTV to continue on to rendezvous with the Station.<\/p>\n
\u201cFree flight demonstrations are planned for all of safety critical functions before the flight phase where these functions are needed,\u201d noted one of 16 MOD FRR presentations acquired by L2, with this article covering two of the presentations.<\/p>\n
![\"HT10\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT10.jpg\" "\\"HT10\\"")
\u201cFar Field Rendezvous demonstrations are planned for Flight Day 3 and must be successfully completed prior to integrated options \u2013 including active and passive aborts (5), free drift and absolute GPS. To be reviewed by IMMT on FD6.\u201d<\/p>\nFollowing approval to proceed, real time monitoring and discussions on the status of the flight will be carried out as the vehicle approaches the ISS, with the option to abort at any stage.<\/p>\n
\u201cAny issues \u2013 or failures to meet established success criteria \u2013 will result in rendezvous termination,\u201d noted the Agenda 2 (Mission Overview) FRR presentation.<\/p>\n
As would be expected, the approach of the vehicle \u2013 for the first time \u2013 to the Station, will be closely monitored. This in itself will require new operations to debut for both HTV controllers on the ground, and the crew onboard the ISS.<\/p>\n
\u201cNew Operations: HTV Crew Monitoring (HCM) is performed during R-Bar operations. Consists of dynamic and static overlays viewed on RWS (Robotic Workstation) monitors using truss and MSS cameras,\u201d added the Agenda 3 Flight Director FRR presentation.<\/p>\n
\u201cConsidered a hazard control for loss of a single Rendezvous Sensor (RVS). Requires crew to monitor PROX range and RVS range during approach. Requires use of Inner Capture Volume (ICV). Terminate HTV approach if HTV exceeds upper limit of ICV. Confirmation that HTV is controlling within the ICV prior to HTV free drift.\u201d<\/p>\n
Again, a safe termination of the approach, in the event of a problem \u2013 such as LOS (Loss Of Signal) \u2013 is a priority for the safety of the ISS.<\/p>\n
![\"HT3\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT3.jpg\" "\\"HT3\\"")
\u201cHCM is also used to monitor approach corridor. Dynamic abort corridor. Inside 300m, if LOS with MCC-H (Mission Control Center, Houston) and HTV exceeds abort corridor, crew prime to initiate HTV abort,\u201d added the presentation.<\/p>\n\u201cRendezvous can be terminated via an Abort or a No-Go command (i.e. no burn). Flight rules define burn Go\/No-Go criteria based on system functionality and trajectory limits.<\/p>\n
\u201cHTV will automatically abort for many system failures. Ground initiated abort is required for violation of trajectory limits or certain ISS failure (e.g. loss of attitude control). No-Go (upload of 0 delta V) is only allowed for a few burns that have a 24 hour safe coast trajectory without an abort. All HTV aborts are designed to ensure a minimum X-axis delta V of 1.2 m\/sec.<\/p>\n
\u201cAbort ensures that the HTV drift trajectory will not enter the approach ellipsoid within 24 hours of burn completion. Abort prior to 300 meters is retrograde. Abort during 300 meter yaw around is passive (i.e. no burn). Abort after 300 meter yaw around is posigrade.\u201d<\/p>\n
Robotics and Transfers:<\/p>\n
Among the mission priorities are items such as the successful use of the SSRMS (Space Station Remote Manipulator System) during HTV capture, and its dual use with the Japanese robotic arm.<\/p>\n
The SSRMS will play a key role as the vehicle arrives at the ISS, given it will not dock like previous cargo ships. Instead, the SSRMS \u2013 or Canadarm2 \u2013 will grapple the HTV, before robotic operations will gently translate the new arrival on to the Harmony module.<\/p>\n
![\"HT8\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT8.jpg\" "\\"HT8\\"")
\u201cCapture sequence: Orbit night is prime plan. ISS thrusters are inhibited (CMG only control). SSRMS moves in from High Hover. HTV commanded to free drift (initiates 99 second capture clock). SSRMS final alignment and capture through first and second phase. Crew safing during capture sequence involves SSRMS back-away and for some cases HTV Retreat,\u201d noted a robotics element on the Flight Director FRR presentation.<\/p>\n\u201cTrack and Capture: First free flyer capture for SSRMS. Enhanced on-board training to support maintenance of track and capture skills.<\/p>\n
\u201cHot Backup: Provides capability to quickly switch SSRMS strings. ~90 seconds from failure recognition to completion of string swap. Standard string swaps required 20-30 minutes. Allows for continuation of capture or HTV release for partial capture scenarios.\u201d<\/p>\n
Any problems \u2013 resulting in delays to the operations \u2013 during the robotics to berth the HTV on Station will result in the vehicle being held in an overnight park position, while the crew prepare to attempt the docking the following day.<\/p>\n
\u201cHTV proximity operations, capture, berthing and critical activation are performed in one day. Crew workday is 7.5 hours (1 hour beyond standard workday), but in family with critical\/complex activities.<\/p>\n
\u201cIf delays are expected to exceed a 10 hour work day, HTV will be taken to an Overnight Park position. Overnight park would also be used for an issue identified during PCBM inspection.<\/p>\n
\u201cBeta dependent park positions (4 total) designed to optimize HTV power generation. Although optimized for power generation, overnight park will result in primary battery power draw if overnight park is required.\u201d<\/p>\n
![\"HT6\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT6.jpg\" "\\"HT6\\"")
Further robotics will be involved when the HTV\u2019s Exposed Pallet (EP) is handed over to the Japanese arm (JEM-RMS), which will then locate the EP on to the Exposed Facility (JEM-EF), following its own recent installation during STS-127.<\/p>\n\u201cEP removal from ULC via SSRMS. SSRMS to JEM RMS handoff of EP. JEM RMS installation of EP on JEM-EF,\u201d noted Flight Day 10 activities in the FRR mission overview presentation.<\/p>\n
\u201cExposed Pallet Removal and Insertion: Crew will command EP latch mechanisms for release and re-installation (single use only \u2013 parafin actuated mechanisms).<\/p>\n
\u201cSSRMS used to remove and install the EP. Installation is planned with Force Moment Accommodation (FMA). Provides closed loop feedback to alleviate loads.<\/p>\n
\u201cFirst time use outside of commissioning. Installation can be performed without FMA if issues arise.<\/p>\n
\u201cHTV Berthing Camera System (HBCS) on EP used for EP alignment and insertion. Video sent to RWS for use with HBCS overlay. Target inside HTV.\u201d<\/p>\n
![\"HT4\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT4.jpg\" "\\"HT4\\"")
The handoff operations between the SSRMS and JEM RMS will also be another first for the ISS.<\/p>\n\u201cSSRMS to JEM RMS Handoff: EP is handed off between SSRMS and JEM RMS for transfer to\/from HTV and the JEF. First handoff between SSRMS and JEM RMS. Very similar to SSRMS to SRMS handoff,\u201d added the New Operations notes in the FRR presentation.<\/p>\n
\u201cEP Payloads are powered when on SSRMS, but not from JEM RMS. Failure of JEM RMS while EP is grappled would require SSRMS to double-grapple for dynamic load events.\u201d<\/p>\n
This will be followed by Flight Day 12\u2019s: \u201cJEM RMS removal of EP. JEM RMS to SSRMS handoff of EP. SSRMS installation of EP into HTV.\u201d<\/p>\n
The bulk of the HTV work on Station relates to the transfer of the vehicle\u2019s internal cargo \u2013 involving 70 hours of soft stowage transfer and trash (from the ISS) being stowed back on the HTV \u2013 taking place between Flight Day 12 and 28, providing there are no issues with the vehicle during these procedures.<\/p>\n
![\"HT5\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT5.jpg\" "\\"HT5\\"")
\u201cNASA is responsible for cargo packing and transfer. JAXA is responsible for HTV mass property calculations,\u201d added the FRR documentation.<\/p>\n\u201cHTV has a fairly large acceptable region for c.g. (Center of Gravity) placement. Although this c.g. volume is considered acceptable from a GNC stand-point, the actual knowledge must be maintained in a tighter region with sufficient time for HTV to upload key GNC control parameters.<\/p>\n
\u201cFor early end of mission (EOM), the tight nominal EOM (End Of Mission) c.g. will not be met. No specific scenario identified for early EOM.<\/p>\n
\u201cCould be needed for unexpected scenarios such as HTV power dropping below redlines, propellant leaks or an ISS emergency requiring HTV hatch closure.<\/p>\n
\u201cGross cargo balancing constraints have been defined with and without EP to allow for gross c.g. placement within envelope. Allows JAXA to pre-design a contingency GNC parameter to protect for early HTV release.<\/p>\n
\u201cNominal departure will utilize a much smaller c.g. envelope and refined GNC parameters. Early EOM response expected to take at least 24 hours.\u201d<\/p>\n
![\"HT11\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT11.jpg\" "\\"HT11\\"")
On Flight Day 29, the SSRMS will be translated back to the HTV for grappling, before the maneuver to release position. Flight Day 30 will see the SSRMS release, ahead of the HTV\u2019s departure burns to gain distance from the ISS.<\/p>\nAround two days later, the HTV will end its mission \u2013 and its life \u2013 with a destructive re-entry.<\/p>\n
\u201cDeparture Burns: 4 burns (IDM1, IDM2, DSM1, DSM2). Open loop burns preloaded before release. Trajectory is 24-hour safe and outside the approach ellipsoid after IDM2. End of integrated operations.\u201d<\/p>\n
Contingencies:<\/p>\n
The mission can suffer several issues and still result in a successful operation. This is due to inbuilt contingency margins, as listed in the FRR documentation.<\/p>\n
The majority of the contingency notes relate to the aforementioned rendezvous termination. However, it\u2019s the recovery process that allows the mission to get back on track, as noted in the Flight Director FRR presentation.<\/p>\n
![\"HT2\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/HT2.jpg\" "\\"HT2\\"")
\u201cTo simplify and minimize recovery maneuver options and to allow for troubleshooting, re-rendezvous is planned for 48 hours. First maneuver following breakout is 10-20 hours after the Abort\/No-Go.<\/p>\n\u201cAll recovery maneuvers are performed outside of the approach ellipsoid (AE). Recovery targeting ensures HTV meets trajectory safety criteria (24 hour coast trajectory will not enter the AE).<\/p>\n
\u201cHTV goes to a point aft on the V-bar called V-bar Point Rear (VPR) where it will station-keep (90 km \u2013 200 km+). AI departure and capture times are fixed with respect to GMT so the same crew\/ground timeline is used.\u201d<\/p>\n
In fact, due to the power margins on the ISS, a total of four rendezvous are available \u2013 the initial and three re-rendezvous attempts \u2013 over a 48 hour period.<\/p>\n
\u201cMission specific power analysis for launch shows sufficient primary battery power to support the following: Nominal rendezvous. 3 re-rendezvous attempts (48 hour turnaround). Overnight Park. ISS contingency allocation of 12 hours standalone power. HTV relocation to Node 2 zenith and back to nadir.<\/p>\n
\u201cProp assessments predict sufficient margin to support 3 rerendezvous attempts. HTV consumables status will be reported periodically throughout the mission. During integrated operations, re-rendezvous and capture redlines are reported at AI, 300 meters, and 30 meters.\u201d<\/p>\n
Other contingencies are also available, with notes relating to the potential use of EVAs from ISS crewmembers, although strict rules are in place for such a requirement.<\/p>\n
L2 members<\/em><\/em>: Documentation \u2013 from which the above article has quoted snippets \u2013 is available in full in the related L2 sections, now over 4000 gbs in size.<\/em><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
After a wait of nearly a decade, the International Space Station is just a matter of weeks away from welcoming another new visitor, in the form of the Japanese HTV (H-II Transfer Vehicle). NASA recently held a Flight Readiness Review (FRR) for their role in aiding the cargo vehicle\u2019s debut stay at the orbital outpost, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[1839,233,877],"class_list":["post-41018","post","type-post","status-publish","format-standard","hentry","category-news","tag-htv","tag-iss","tag-jaxa"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41018"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=41018"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41018\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=41018"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=41018"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=41018"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}